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Technical Committee on Lightning Protection
ROC Meeting Agenda
October 9-12, 2012
Orlando, FL
Day 1, October 9, 2012:
0800: Call to Order.
0800-0830: Roll Call/ Opening Remarks/Approval of Meeting Agenda/Approval of Meeting Minutes.
0830-0900: Introduction, 2014 cycle schedule recap, administrative topics.
0900-1200: Address comments.
1200-1300: Lunch.
1300-1630: Address comments.
1630-1700: Review actions.
Day 2, October 10, 2012:
0800: Call to Order.
0800-0830: Introduction, administrative topics.
0830-1200: Address comments.
1200-1300: Lunch.
1300-1630: Address comments.
1630-1700: Review actions.
Day 3, October 11, 2012:
0800: Call to Order.
0800-0830: Introduction, administrative topics.
0830-1200: Address comments.
1200-1300: Lunch.
1300-1630: Address comments.
1630-1700: Review actions.
Day 4, October 12, 2012:
0800: Call to Order.
0800-0830: Introduction, administrative topics.
0830-1200: Address comments if needed. Old Business/New Business/Review Dates and Times for
Future Meetings/Review new standards process/TGs/Conclusion.
Minutes of the Technical Committee on Standard for the Installation of Lightning Protection Systems
of March 29, 2012
Item 12-3-1, Call to Order
John Tobias, Chair, called the Meeting/Conference call of March 21, 2011 to order at 1:00 pm (EASTERN).
Item 12-3-2, Roll Call
Participants:
John Tobias
Robert Daley
Douglas Franklin
Mitchell Guthrie
Thomas Harger
David McAfee
Robley Melton
Victor Minak
Mark Morgan
Luke Pettross
Terrance Portfleet
Robert Rapp
Lon Santis
Russell Stubbs
Richard Bouchard
Stephen Humeniuk
Staff:
Richard Roux
Attendance was sixteen (16), and one NFPA staff, for a total of seventeen (17) attendees.
Item 12-3-3, Opening Remarks
The Chair thanked all for their participation.
Item 12-3-4, Approval of Meeting Agenda
The meeting agenda was approved.
Item 12-3-5, Review of Proposal ROP 780-23 (Log #70)
Staff explained that during the processing of the ROP, it was noted that ROP 780-23 was incomplete as
several sections were not carried into the proposal by the committee action as intended.
After review and discussion by the TC, it was moved, seconded and unanimously voted affirmatively to
accept the revised text. The text would be placed in the ROP replacing existing ROP 780-23 (Log #70).
Item 12-3-6, Old Business
None
Item 12-3-7, New Business
Staff noted that the ROC is scheduled for Orlando, October 9 – 12. The meeting will end at noon on the
12th.
Item 12-3-8, Review Dates and Times for Future Conference Calls
No future Meeting/Conference call is scheduled.
The Chair noted that when the ROP is printed and the draft available, he will reconvene some of the Task
Groups.
Item 12-3-9, Adjournment and Closing Remarks
John Tobias thanked all for their participation.
The meeting/conference call adjourned at 10:00 am (EASTERN).
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-1 Log #30
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
N/A
There is some introduction of reversing the English and Metric designation priorities with changes
by various Proposals.
We need consistency.
_______________________________________________________________________________________________
780-2 Log #63
_______________________________________________________________________________________________
Matthew Caie, ERICO, Inc.
780-5
None provided.
Conflict over Committee Scope and Document Scope.
Document now stating scope over an area not covered in the scope of the committee as stated in the document.
Propose to expand ROP-5 to address/adjust accordingly committee scope.
A.1.1.2 also needs to be updated in line with scope.
_______________________________________________________________________________________________
780-3 Log #1
_______________________________________________________________________________________________
John F. Bender, UL LLC
780-6
Revise text to read as follows:
Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062–2096.
ANSI/UL 1449,
, Third Edition, September 29, 2006, Revised 2011.
This proposal is being re-submitted with updated revision dates as indicated, with the request that the
committee reconsider adding such revision dates, in addition to the initial publication date of the standard, to reflect the
most recent technical update of the standard as revised from time to time by the UL Standard Technical Panel
responsible for each of the respective standards. Reference to the initial publication date of the standard and any
subsequent revision date for that standard is consistent with almost all other NFPA Standards, such as NFPA 72 and
NFPA 101 as two prime examples.
_______________________________________________________________________________________________
780-4 Log #81
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-108
Add new text:
3.3.2 Bonded (Bonding) (For the purposes of Chapter II only). Connected to establish electrical continuity and
conductivity. [70:2011]
Text clarifies that this definition of bonding applies only to Chapter 11. The existing definition for
bonding applies to the rest of the document.
Printed on 9/18/2012
1
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-5 Log #32
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-108
Revise Definition of Couterpoise Conductor to read as follows:
A bare underground electrical conductor providing an area of protection from the effects of lightning for underground
raceway(s) or cable(s).
The counterpoise conductor functions to protect from surges originating at another point of strike, not
just if that particular circuit is struck.
_______________________________________________________________________________________________
780-6 Log #44
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Add new definition for I
Shows up in Section 4.15.3 and we have not defined this within our document.
_______________________________________________________________________________________________
780-7 Log #45
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Add new definition for
Shows up in Section 4.15.3.1 and we have not defined this within our document.
_______________________________________________________________________________________________
780-8 Log #33
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-7
Revise text to read as follows:
byship should be changed to by ship
Grammatical form correction.
_______________________________________________________________________________________________
780-9 Log #17
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Revise text to read as follows:
Shoulder Pavement. Pavement designed to provide support of an aircraft for unintentional or
emergency operations of the aircraft.
Shoulder pavement definition should be included under the overall 3.3.32 Pavement grouping with the
other pavement related definitions. Consistent with approved ROP-108 text.
Renumber definitions starting at 3.3.34.
Printed on 9/18/2012
2
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-10 Log #31
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-6a
....ground electrode..... should be changed to .....grounding electrodes....
To maintain the same terminology as paragraph 3.3.18.
_______________________________________________________________________________________________
780-11 Log #56
_______________________________________________________________________________________________
Mitchell Guthrie, Independent Engineering Consultant
780-11
Do not delete "ordinary" in Section 4.1.1.1(1).
In deleting "ordinary" from Section 1.1.1(1) there is no need to add anything else in the list as they are
all structures with various occupancies and the list makes no sense. Ordinary is needed to identify the difference
between (1) and the other items in the list. A less preferred option would be to add "with ordinary occupancies" to
"structures" in (1).
_______________________________________________________________________________________________
780-12 Log #34
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-13a
Revise text to read as follows:
Beside or under 57,400 cir mils, add 2 AWG and beside or under 26,240 cir mils, add 6 AWG.
The reader may not have the proper wire chart and it is a simple thing to add the common designation
of wire size. We have AWG listed for each strand already, so there is no introduction of something new.
_______________________________________________________________________________________________
780-13 Log #35
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-13a
Revise text to read as follows:
Beside or under 115,000 cir mils, add 2/0 and beside or under 26,240 cir mils, add 6 AWG.
The reader may not have the proper wire chart and it is a simple thing to add the common designation
of wire size. We have AWG listed for each strand already, so there is no introduction of something new.
_______________________________________________________________________________________________
780-14 Log #72
_______________________________________________________________________________________________
John M. Tobias, US Army Communications Electronics Command
780-16
Revise as follows:
4.1.2.4 Protection for a shed roof shall be as illustrated for the gable method typical roof types shall be as illustrated in
Figure 4.1.2.4. Spacing of air terminals shall comply with 4.8.1. (Section 4.8.1 moves to 4.7.2 in ROP edition.)
Statement adds clarity to the application of the figures and affirms that the air terminal spacing
requirements remain in effect for these permitted protection schemes.
Printed on 9/18/2012
3
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-15 Log #74
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-23
****Insert Include 780_L74_R.doc Here
The Joint Strike Termination/Modeling Task Groups recognized the original intent of reorganizing these
sections was not fully accomplished by the TC Meeting action on this proposal. The intent was to organize the sections
such that requirements for strike termination devices were first, followed by descriptions and requirements for locating
strike
termination devices on the various types of roofs and objects on roofs. These requirements are then followed by
requirements for determining where strike termination devices are not required using the protective angle methods for
multiple roof levels and finally the rolling sphere method. The Joint Task Groups feel this reorganized text meets the
intent. The submitter realizes that other proposals and comments will change this text. The purpose of this comment is
set the order of these three sections.
_______________________________________________________________________________________________
780-16 Log #64
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-19
Revise text to read as follows:
A fixed metal object that has moveable components shall be allowed to be used as a strike termination device
under the following conditions.
(1) The highest surface is greater than 4.8 m (3/16 in.) thick in accordance with Section 4.6.1.4.
(2) The fixed portion is attached to the lightning protection system in accordance with Section 4.9.
(3) The point of articulation between the fixed portion and the moveable portion is constructed entirely of metal.
(4) All other portions of the device are electrically continuous.
The committee's reason to reject is invalid. The suggested change complies with the definition of
Strike Termination Device as set forth in Section 3.3.29 and Section 4.9 Conductors that Section 3.3.29 improperly
references. Section 3.3.29 should reference Section 4.8 Strike Termination Devices on Roofs, which also does not
conflict with the proposal as set forth. There is another reference to Strike Termination Devices; Section 4.16.2 which
also does not provide any contradictory criteria to that set forth in this proposal.
Printed on 9/18/2012
4
FORM FOR COMMENT ON NFPA REPORT ON PROPOSALS
All Comments Must Be Received by 5:00 pm EST/EDST
on the Published Comment Closing Date
FOR OFFICE USE ONLY
For further information on the standards-making process, please contact the Codes
and Standards Administration at 617-984-7249 or visit www.nfpa.org/codes.
Log #:
For technical assistance, please call NFPA at 1-800-344-3555.
Date Rec’d:
Please indicate in which format you wish to receive your ROP/ROC
electronic
paper
download
(Note: If choosing the download option, you must view the ROP/ROC from our website; no copy will be sent to you.)
Date
Name
8/30/2012
Company
Tel. No.
Thomas R. Harger
Harger, Inc.
Street Address
City
301 Ziegler Drive
Grayslake
847-543-5028
Email
[email protected]
State
IL
Zip
60030
***If you wish to receive a hard copy, a street address MUST be provided. Deliveries cannot be made to PO boxes.
Please indicate organization represented (if any)
1. (a) NFPA Document Title
(b) Section/Paragraph
Standard for the Installation of Lightning Protection
Systems
NFPA No. & Year
780-2011
4.6, 4.7, and 4.8
2.
Comment on Proposal No. (from ROP):
3.
Comment Recommends (check one):
780-23
new text
revised text
deleted text
4. Comment (include proposed new or revised wording, or identification of wording to be deleted): [Note: Proposed text
should be in legislative format; i.e., use underscore to denote wording to be inserted (inserted wording) and strike-through to denote
wording to be deleted (deleted wording).]
Reorganize sections 4.6 through 4.8 as follows:
4.6 Strike Termination Devices.
4.6.1 General.
4.6.1.1 Strike termination devices shall include air terminals, metal masts, permanent metal parts of
structures as described in 4.6.1.4, and overhead ground wires.
4.6.1.2
Combinations of these strike termination devices shall be permitted.
4.6.1.3
Strike termination devices shall be provided where required by other sections of this standard.
4.6.1.4 Metal parts of a structure that are exposed to direct lightning flashes and that have a metal thickness
of 4.8 mm (3⁄16 in.) or greater shall require only connection to the lightning protection system in accordance
with Section 4.7.
4.6.1.5 Strike termination devices shall not be required for those parts of a structure located within a zone
of protection.
4.6.2 Air Terminals.
4.6.2.1* The tip of an air terminal shall be not less than 10 in (254 mm) above the object or area it is to
protect, as shown in Figure 4.6.2.1.
FIGURE 4.6.2.1 Air Terminal Height.
4.6.2.2 Air Terminal Support.
4.6.2.2.1 Air terminals shall be secured against overturning or displacement by one of the following
methods:
(1) Attachment to the object to be protected
(2) Braces that are permanently and rigidly attached to the structure
4.6.2.2.2 Air terminals exceeding 600 mm (24 in.) in height shall be supported at a point not less than onehalf their height, as shown in Figure 4.6.2.2.2.
FIGURE 4.6.2.2.2 Air Terminal Support.
4.6.2.3 Ornaments.
4.6.2.3.1 An ornament or decoration on a freestanding, unbraced air terminal shall not present, in any plane,
a wind-resistance area in excess of 0.01 m2 (20 in.2).
4.6.2.3.2 The requirement of 4.6.2.3.1 shall permit the use of an ornamental ball 127 mm (5 in.) or less in
diameter.
4.6.3 Lightning Protection Masts.
4.6.3.1
Lightning protection masts shall be permitted to provide a zone of protection.
4.6.3.2
Metal masts shall comply with 4.6.1.4 or be protected with a strike termination device.
4.6.3.3
Nonmetallic masts shall be provided with at least one strike termination device.
4.6.3.4 The top of the metallic mast shall have a metal thickness of 4.8 mm (3⁄16 in.) or greater or be
provided with at least one strike termination device.
4.6.3.5 The mast shall be permitted to serve as the down conductor, provided it is electrically continuous
and has a wall thickness of 1.63 mm (0.064 in.) minimum.
4.6.4 Overhead Ground Wires.
4.6.4.1
Overhead ground wires shall be permitted to provide a zone of protection.
4.6.4.2 Overhead ground wire material shall be constructed of aluminum, copper, stainless steel, galvanized
steel, or protected steel such as copper-clad, aluminum-clad, or aluminum conductor steel reinforced
(ACSR).
4.6.4.3
site.
The overhead ground wire material shall be chosen to minimize corrosion from conditions at the
4.6.4.4 The overhead ground wire shall be sized to have the same cross-sectional area as a main lightning
conductor and shall be self-supporting with minimum sag under all conditions.
4.6.5* Isolated Masts and Overhead Ground Wires. To prevent sideflashes, the minimum distance
between a mast or overhead ground wire and the structure to be protected shall be calculated.
4.6.5.1
Sideflash distance from a mast shall be calculated from the following formula:
where:
D = sideflash distance from a mast
h = height of structure (or object being calculated)
4.6.5.2
where:
D=
l=
n=
n=
The sideflash distance from an overhead ground wire shall be calculated as follows:
sideflash distance from a mast or overhead ground wire
length of lightning protection conductor between its grounded point and the point being calculated
1 where there is one or less overhead ground wire that exceeds 30 m (100 ft) in horizontal length
1.5 where there is one or two down conductors spaced greater than 7.6 m (25 ft) and less than 30 m
(100 ft) apart
n = 2.25 where there are more than two down conductors spaced more than 7.6 m (25 ft) apart within a 30
m (100 ft) wide area that are interconnected above the structure being protected
4.7 Strike Termination Devices on Roofs.
4.7.1 Roof Types. Protection requirements for the following roof types shall include the roof and
appurtenances in accordance with this Section:
(1) Pitched roofs
(2) Flat or gently sloping roofs
(3) Dormers
(4) Domed roofs
(5) Roofs with ridges, wells, chimneys, or vents
4.7.1.1 Pitched roofs shall be defined as roofs having a span of 12 m (40 ft) or less and a slope 1/8 or greater,
and roofs having a span of more than 12 m (40 ft) and a slope 1/4 or greater.
4.7.1.2
A flat or gently sloping roof is defined as a roof with a slope less than a pitched roof.
4.7.1.3
For purposes of this standard, roof pitches shall be as shown in Figure 4.7.1.3.
FIGURE 4.7.1.3 Roof Slope
4.7.1.4
Protection for typical roof types shall be as illustrated in Figure 4.7.1.4.
FIGURE 4.7.1.4 Protection Measures for Various Roof Types
(Drawings are top and end views of each roof type.)
4.7.1.5 Roof hips shall not be considered as ridges for the protection of these types of roofs.
4.7.2* Location of Devices.
4.7.2.1 As shown in Figure 4.7.2.1, the distance between strike termination devices and ridge ends on
pitched roofs, or edges and outside corners of flat or gently sloping roofs, shall not exceed 0.6 m (2 ft).
FIGURE 4.7.2.1 Air Terminals on a Pitched Roof.
4.7.2.2 Strike termination devices shall be placed on ridges of pitched roofs, and around the perimeter of
flat or gently sloping roofs, at intervals not exceeding 20 ft (6 m).
4.7.2.3 Strike termination devices 2 ft (0.6 m) or more above the object or area to be protected shall be
permitted to be placed at intervals not exceeding 25 ft (7.6 m).
4.7.3 Pitched Roof Areas
4.7.3.1 For pitched roofs with eave heights over 15 m (50 ft) but less than46 m (150 ft) above grade, it shall
be permitted to omit strike termination devices at the eaves if the slope of that roof is equal to or steeper than
the tangent of the arc at the eave elevation of a rolling sphere having a 46 m (150 ft) radius. (See Figure
4.7.3.1.)
FIGURE 4.7.3.1 Illustration of Tangent of Rolling Sphere Method.
4.7.3.2
Except for the gutter, any portion of the building that extends beyond that tangent shall be protected.
4.7.3.4 Eaves over 150 ft (46 m) above grade shall be protected in accordance with 4.7.2.
4.7.3.5 The tangent of the rolling sphere arc shall be considered a vertical line over 46 m (150 ft) above
grade, except as permitted by 4.8.2.4.
4.7.3.6 Roofs with Intermediate Ridges. Strike termination devices shall be located along the outermost
ridges of buildings that have a series of intermediate ridges at the same intervals as required by 4.7.1.
4.7.3.7.1 Strike termination devices shall be located on the intermediate ridges in accordance with the
requirements for the spacing of strike termination devices on flat or gently sloping roofs.
4.7.3.7.2 If any intermediate ridge is higher than the outermost ridges, it shall be treated as a main ridge and
protected according to 4.7.1.
4.7.4 Flat or Gently Sloping Roofs. Flat or gently sloping roofs that exceed 50 ft (15 m) in width or length
shall have additional strike termination devices located at intervals not to exceed 50 ft (15 m) on the flat or
gently sloping areas, as shown in Figure 4.7.4(a) and Figure 4.7.4(b), or such area can also be protected using
taller strike termination devices that create zones of protection using the rolling sphere method so the sphere
does not contact the flat or gently sloping roof area.
FIGURE 4.7.4(a) Air Terminals on a Flat Roof.
FIGURE 4.7.4(b) Air Terminals on a Gently Sloping Roof.
4.7.5 Flat or Gently Sloping Roofs with Irregular Perimeters. Structures that have exterior wall designs
that result in irregular roof perimeters shall be treated on an individual basis.
4.7.5.1 The imaginary roof edge formed by the outermost projections shall be used to locate the strike
termination devices in accordance with 4.7.1.
4.7.5.2
In all cases, however, strike termination devices shall be located in accordance with Section 4.7 as
shown in Figure 4.7.6.2.
FIGURE 4.7.5.2 Flat or Gently Sloping Roof with an Irregular Perimeter.
4.7.6* Dormers.
4.7.6.1 Dormers as high as or higher than the main roof ridge shall be protected with strike termination
devices, conductors, and grounds.
4.7.6.2 Dormers and projections below the main ridge shall require protection only on those areas
extending outside a zone of protection.
4.7.7 Strike termination devices installed on vertical roof members shall be permitted to use a single mainsize cable to connect to a main roof conductor.
4.7.7.1 The main roof conductor shall be run adjacent to the vertical roof members so that the single cable
from the strike termination device is as short as possible and in no case longer than 4.9 m (16 ft).
4.7.7.2 The connection of the single cable to the down conductor shall be made with a tee splice or other
fitting listed for the purpose, as shown in Figure 4.7.6.2.
FIGURE 4.7.7.2 Irregular Roof Perimeter.
4.7.8 Open Areas in Flat Roofs. The perimeter of open areas, such as light or mechanical wells, shall be
protected if the open area perimeter exceeds 92 m (300 ft), provided both rectangular dimensions exceed 15
m (50 ft).
4.7.9 Domed or Rounded Roofs. Strike termination devices shall be located so that no portion of the
structure is located outside a zone of protection, as set forth in Section 4.8.
4.7.10 Chimneys and Vents. Strike termination devices shall be required on all objects on roofs that are not
located within a zone of protection, including metal having a metal thickness of less than 4.8 mm (3⁄16 in.).
4.7.10.1 Chimneys or vents with a metal thickness of 4.8 mm (3⁄16 in.) or more shall require connection to
the lightning protection system.
4.7.10.2 The connection for 4.7.9.1 shall be made using a main size lightning conductor and a connector
that has a surface contact area of not less than 1940 mm2 (3 in.2) and shall provide two or more paths to
ground, as is required for strike termination devices.
4.7.10.3* Required strike termination devices shall be installed on objects on roofs, as shown in Figure
4.7.10.3, so that the distance from a strike termination device to an outside corner or the distance
perpendicular to an outside edge is not greater than 0.6 m (2 ft).
FIGURE 4.7.10.3 Air Terminals on a Chimney.
4.7.10.4 Where only one strike termination device is required on a an object, at least one main-size
conductor shall connect the strike termination device to a main conductor at the location where the object
meets the roof surface and provides two or more paths to ground from that location in accordance with
Section 4.9 and 4.9.2.
4.7.11 Metal Roof Top Units. Strike termination devices shall be required in accordance with 4.7.10.1
through 4.7.10.3.2 on all roof top mechanical units with continuous metal housings less than 4.8 mm (3⁄16 in.)
thick such as air-conditioning/heating units, metal air intake/exhaust housings, and cooling towers, that are
not located in a zone of protection.
4.7.11.1
Air terminals shall be installed in accordance with 4.7.1 through 4.7.3.
4.7.11.2 The air terminals shall be mounted on bases having a minimum contact area of 1940 mm2 (3 in.2),
each secured to bare metal of the housing or mounted by drilling and tapping to the unit's frame in
accordance with 4.16.3.2 and 4.16.3.3.
4.7.11.3
system.
At least two main-size conductors shall be installed to connect the unit to the lightning protection
4.7.11.3.1 The connection shall be made to bare metal at the base or lower edges of the unit using main-size
lightning conductors and bonding devices that have a surface contact area of not less than 1940 mm2 (3 in.2)
and shall provide two or more paths to ground, as is required for strike termination devices.
4.7.11.3.2 The two main bonding plates shall be located as far apart as practicable at the base or lower
edges of the unit's electrically continuous metal housing and connected to the lightning protection system.
4.8 Zones of Protection. The geometry of the structure shall determine the zone of protection.
4.8.1 One or more of the methods described in 4.7.1 through 4.8 shall be use to determine the overall zone
of protection.
4.8.2 Multiple-Level Roofs.
4.8.2.1 For structures with multiple-level roofs no more than 15 m (50 ft) in height, the zone of protection
shall include areas as identified in 4.8.2.3 and 4.8.2.4.
4.8.2.2 The zone of protection shall be permitted to be delineated by a cone with the apex located at the
highest point of the strike termination device, with its surface formed by a 45-degree or 63-degree angle from
the vertical, based on the height of the strike termination device above the ground as defined in 4.8.2.3 and
4.8.2.4.
4.8.2.3 Structures that do not exceed 7.6 m (25 ft) above earth shall be considered to protect lower portions
of a structure located within a one-to-two zone of protection as shown in Figure 4.8.2.3(a) and Figure 4.8.2.3
(b).
FIGURE 4.8.2.3(a) Lower Roof Protection for Flat-Roof Buildings 7.6 m (25 ft) or Less in Height.
FIGURE 4.8.2.3 (b) Lower Roof Protection Provided by Pitched-Roof Buildings 7.6 m (25 ft) or Less
in Height.
4.8.2.4* Structures that do not exceed 15 m (50 ft) above earth shall be considered to protect lower portions
of a structure located within a one-to-one zone of protection as shown in Figure 4.8.2.4(a) and Figure
4.8.2.4(b).
FIGURE 4.8.2.4 (a) Lower Roof Protection for Buildings 15 m (50 ft ) or Less in Height.
FIGURE 4.8.2.4 (b) Lower Roof Protection Provided by Pitched-Roof Buildings 15 m (50 ft) or Less
in Height.
4.8.3 Rolling Sphere Method.
4.8.3.1* The zone of protection shall include the space not intruded by a rolling sphere having a radius of the
striking distance determined for the type of structure being protected, as shown in Figure 4.8.3.1.
FIGURE 4.8.3.1 Zone of Protection Depicting Rolling Sphere Method.
4.8.3.1.1 Where the sphere is tangent to earth and resting against a strike termination device, all space in
the vertical plane between the two points of contact and under the sphere shall be considered to be in the zone
of protection.
4.8.3.1.2 A zone of protection shall also be formed where such a sphere is resting on two or more strike
termination devices and shall include the space in the vertical plane under the sphere and between those
devices, as shown in Figure 4.8.3.1
4.8.3.1.3 All possible placements of the sphere shall be considered when determining the overall zone of
protection using the rolling sphere method.
4.8.3.1.4
The striking distance shall not exceed 46 m (150 ft).
4.8.3.2* For structure heights exceeding the striking distance above earth or above a lower strike termination
device, the zone of protection shall be the space in the vertical plane between the points of contact, and also
under the sphere where the sphere is resting against a vertical surface of the structure and the lower strike
termination device(s) or earth.
4.8.3.3 Under the rolling sphere method, the horizontal protected distance found geometrically by Figure
A.4.8.3.1 also shall be permitted to be calculated using the following formula (units shall be consistent, m or
ft):
where:
d=
h1 =
R=
h2 =
horizontal protected distance (m or ft)
height of the higher roof (m or ft)
rolling sphere striking distance radius (m or ft)
height of the lower roof (top of the object)(m or ft)
4.8.3.3.1 For the formula to be valid, the sphere shall be either tangent to the lower roof or in contact with
the earth, and in contact with the vertical side of the higher portion of the structure.
4.8.3.3. 2 In addition, the difference in heights between the upper and lower roofs or earth shall be the
striking distance or less.
Also: Renumber existing Annex A items as follows:
Old A.4.7.3.4 to new A.4.8.2.4
Old figure A.4.7.3.4 to Figure A.4.8.2.4
Old A.4.7.4.1 to new A.4.8.3.1
Old Figure A.4.7.4.1 to Figure A.4.8.3.1
OldA.4.7.4.2 to new A.4.8.3.2
Old A.4.8.1 to new A.4.7.2
Old A.4.8.4 to new A.4.7.6
Old Figure A.4.8.4 to new Figure A.4.7.6
Old A.4.8.9.3 to new A.4.7.10.3
5. Statement of Problem and Substantiation for Comment: (Note: State the problem that would be resolved by your
recommendation; give the specific reason for your Comment, including copies of tests, research papers, fire experience, etc. If more
than 200 words, it may be abstracted for publication.)
The Joint Strike Termination/Modeling Task Groups recognized the original intent of reorganizing these sections was not
fully accomplished by the TC Meeting action on this proposal. The intent was to organize the sections such that
requirements for strike termination devices were first, followed by descriptions and requirements for locating strike
termination devices on the various types of roofs and objects on roofs. These requirements are then followed by
requirements for determining where strike termination devices are not required using the protective angle methods for
multiple roof levels and finally the rolling sphere method. The Joint Task Groups feel this reorganized text meets the
intent. The submitter realizes that other proposals and comments will change this text. The purpose of this comment is
set the order of these three sections.
6. Copyright Assignment
(a)
I am the author of the text or other material (such as illustrations, graphs) proposed in the Comment.
(b)
Some or all of the text or other material proposed in this Comment was not authored by me. Its source is as
follows: (please identify which material and provide complete information on its source)
Text is a reorganization of current text of NFPA 780-2011
I hereby grant and assign to the NFPA all and full rights in copyright in this Comment and understand that I acquire no rights in any publication of NFPA
in which this Comment in this or another similar or analogous form is used. Except to the extent that I do not have authority to make an assignment in
materials that I have identified in (b) above, I hereby warrant that I am the author of this Comment and that I have full power and authority to enter into
this assignment.
Signature (Required)
PLEASE USE SEPARATE FORM FOR EACH COMMENT
Mail to: Secretary, Standards Council ∙ National Fire Protection Association
1 Batterymarch Park ∙ Quincy, MA 02169-7471 OR
Fax to: (617) 770-3500 OR Email to: [email protected]
9/10/2012
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-17 Log #84
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc.
780-20
Revise Figure 4.6.2.2.2 so that the leader for dimension "A" extends down to the support point.
****Insert Artwork Here****
Figure 4.6.2.2.2
Bottom of leader points to top of parapet which is not the point of support as stated in the text. As
shown, it would be interpreted to be 24 inches above the top of the parapet.
_______________________________________________________________________________________________
780-18 Log #36
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-21
Propose the addition of drawings or sketches to illustrate the use of n=1, n=1.5 and n=2.25, and a
re-Iook at the wording of the description for when each "n" is used.
With typical overhead systems, the masts are always greater than 100 feet apart, so 1.5 and 2.25
might rarely be applicable, as written. Even if masts are tied together in a grid-type system (two overhead wires off the
same mast), at a distance between masts of greater than 100 feet we could never meet the "more than 25 feet within a
100 foot wide area" because the "interconnection" is basically at a distance of zero. I see the "100 foot wide area" as a
100 foot radius. The intent of the distances in this section is unclear.
_______________________________________________________________________________________________
780-19 Log #38
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-21
Add new text to read as follows:
Add the asterisk to note additional information in the appendix (if separate comment is accepted).
Printed on 9/18/2012
5
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-20 Log #73
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-21
Revise 4.6.5.2 as follows:
4.6.5.2 The sideflash distance from an overhead ground wire shall be calculated as follows:
****Insert Equation 4.6.5.2 Here****
where:
= sideflash distance from a mast or overhead ground wire
= length of lightning protection conductor between its grounded point and the point being calculated
= 1 where there is one or less overhead ground wire that exceeds 30 m (I 00 ft) in horizontal length
= 1.5 where there is one or two down conductors connected to the overhead ground wire spaced greater than 7.6 m
(25 ft) and less than 30 m (100 ft) apart along the length of the overhead ground wire.
= 2.25 where there are more than two down conductors connected to the overhead ground wire spaced more than 7.6
m (25 ft) apart within a and less than 30 m (100 ft) wide area that are interconnected above the structure being
protected apart along the length of the overhead ground wire.
Add new Figure 4.6.5.2.
****Insert Artwork Figure 4.6.5.2 Here****
Revised text clarifies that down conductors must be connected to the overhead ground wire and that r is
measured along the wire, not just in the "area"
Figure is added to show an example of how n = 2.25.
_______________________________________________________________________________________________
780-21 Log #65
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-23
Review text as written and edit to comply with the manual of style.
Language as set forth does not meet the criteria as set forth in the manual of style.
Printed on 9/18/2012
6
𝐷=
𝑙
6𝑛
NFPA 780 L73 Rec A2013 ROC
780_L73_Figure 4.6.5.2_ROC_A2013
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-22 Log #77
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-29
Revise as follows:
4.7.11.2' Movable or rotating metal objects on roofs that do not pose an additional sideflash hazard to the protected
structure shall be pennitted to be connected to the lightning protection system in accordance with 4.7.9.1
Add Annex material:
A.4.7.11.2 Examples include windsocks, window washing davits and weathervanes where connection of the supporting
masts or sockets to the lightning protection system comply with the requirements of Chapter 4 and arcing within the
metal object will not damage the protected structure.
Changes in requirement attempt to clarify actual hazard and offer relief where acceptable. Annex
materials were added to further explain intent.
_______________________________________________________________________________________________
780-23 Log #39
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-26
Revise text to read as follows:
To integrate with adjacent numbering system and numbered paragraphs.
_______________________________________________________________________________________________
780-24 Log #75
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-26
Add missing text as indicated in TC action.
4.8.2.2 For pitched roofs with a span of 30 m (100 ft) or less and eave heights greater than or equal to 15 m (50 ft) but
less than 46 m (150 ft) above grade, it shall be permitted to omit strike termination devices at the eaves if the slope of
that roof is equal to or steeper than the tangent of the arc at the eave elevation of a rolling sphere
having a 46 m (150 ft) radius.
Added text appeared in 780-2011 and the submitters proposal but was inadvertently left out of the
committee action.
Printed on 9/18/2012
7
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-25 Log #76
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-27
Revise text of committee action as follows:
4,8.9 Chimneys, Vents and Other Objects on Roofs not in a zone of protection. Strike termination devices shall be
required on all objects on roofs that are not located within a zone of protection, including metal objects having a metal
thickness of less than 4.8 mm (~6 in.) except as permitted in this section.
4.8.9.1 Metal objects on roofs not located in a zone of protection with a metal thickness of 4.8 mm (3/16 in.) or more
shall require connection to the lightning protection system using a main-size lightning conductor and a main-size
connector in accordance with thc following:
(1) Has a surface contact area of not less than 1940 mm2 (3 in.2) or a minimum of 38 mm (1 1/2 in.) of contact along the
axis of a round surface
(2) Provide two or more paths to ground, as is required for strike termination devices.
4.8.9.2* Required strike termination devices shall be installed on objects on roofs, as shown in Figure 4.8.9.2, so that
the distance from a strike termination device to an outside comer or the distance perpendicular to an outside edge is not
greater than 0.6 m (2 ft).
4.8.9.3 Where only one strike termination device is required on a an object, at least one main-size conductor shall
connect the strike termination device to a main conductor at the location where the object meets the roof surface and
provides two or more paths to ground from that location in accordance with Section 4.9 and 4.9. 2.
4.8.9.4 Small o Objects on roofs that arc less than 254 mm (10 in.) above the surface of the roof shall not require strike
termination devices unless they are located within 0.9 m (3 ft) of the ridge or roof edge.
In 4.8.9. 4.8.9.1 and 4.8.9.2 the Objects may not be located on the roof. They may be located along
side the roof but extend above the roof.
In 4.8.9.1 it is important that a main·size connector be used.
In 4.8.9.3 the word "Small" is vague and not necessary in this case.
_______________________________________________________________________________________________
780-26 Log #40
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-29
Revise text to read as follows:
or lighting masts should be changed to or a mast system
There is no definition or terminology elsewhere in this document specified as "lightning masts."
Consistency would be achieved with this change.
Printed on 9/18/2012
8
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-27 Log #66
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-32
Modify the existing text as follows:
4.10.1 Attached by nails, screws, bolts or adhesive as necessary, the fasteners shall not be subject to breakage.
4.10.2 Fasteners shall be of the same materials as the conductor or of a material equally resistant to corrosion as that
of the conductor.
Renumber existing Sections 4.10.2 to Section 4.10.3.
The existing text does not conform to the Manual of Style. There is more than one requirement in this
text. A committee proposal was put forward at the ROP meeting that was not addressed.
_______________________________________________________________________________________________
780-28 Log #29
_______________________________________________________________________________________________
Mark P. Morgan, East Coast Lightning Equipment, Inc.
780-34
Add new text\ as follows:
4.13.1.1 Each down conductor shall terminate at a grounding electrode dedicated to the lightning protection system or
to a grounding electrode system in the case of a building, structure or facility that has multiple grounding electrodes that
are bonded together with a ground ring electrode to form the grounding electrode system.
The size of the ground ring electrode shall be equal to or greater than that of a main size conductor found in Table
4.1.1.1.1 and 4.1.1.1.1.2.
The original proposal addresses a problem but some guidance is needed with regard to conductor size
for Class I and Class II installations.
_______________________________________________________________________________________________
780-29 Log #78
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc.
780-34
Add text as follows:
4.13.1.1 Each down conductor shall terminate at a grounding electrode dedicated to the lightning protection system or to
a grounding electrode system in the case of a building, structure or facility that has multiple grounding electrodes that
are bonded together with a ground ring electrode sized in accordance with 4.13.4.2 to form the grounding electrode
system.
Text is added to ensure that the facility ground electrode system meets the requirements for a main-size
conductor.
Printed on 9/18/2012
9
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-30 Log #60
_______________________________________________________________________________________________
Richard Kithil, National Lightning Safety Institute
780-37
Add: "galvanized steel is an acceptable material for grounding purposes."
Justification:
The electric power industry uses galvanized steel below grade for substation grounding. This practice has been in
effect for 100+ years.
_______________________________________________________________________________________________
780-31 Log #41
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-37
The ground ring electrode shall be a main-size lightning conductor as specified in Table 4.1.1.1.1
or a grounding conductor of equivalent or greater cross-sectional area.
Two sizes of main-size conductors are listed in 4.1, depending on height.
_______________________________________________________________________________________________
780-32 Log #42
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-37
The ground ring electrode shall be a Class I main-size lightning conductor, or a grounding
conductor of equivalent or greater cross-sectional area.
There are two main-size conductors, Class I and Class II.
Tables 4.1.1.1.1 and 4.1.1.1.2 call them main-size conductors, not main size lightning conductors.
Printed on 9/18/2012
10
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-33 Log #55
_______________________________________________________________________________________________
Mitchell Guthrie, Independent Engineering Consultant
780-38
Add an asterisk to 4.13.8.1.2 and add the following new text to Annex A:
For applications involving shallow topsoil, the overall earth resistivity is generally high; leading to a high
grounding system resistance. In such applications, the use of radials extending from the structure is encouraged.
However, the high earth resistivity may require a greater radial length than that specified in Section 4.13.5. It is
recommended that the length of radials used in these applications meet the criteria for Type II lightning protection
system as shown in the graph below.
******Insert Figure A.4.13.8.1.2 Here******
This section deals with an application where there is insufficient topsoil to meet the standard
requirements in Section 4.13. For such applications, it is suggested that the overall earth resistivity is increased and the
use of radials is typically the preferred grounding system electrode solution. Since this requirement is applicable for all
applications, it is suggested that the user be encouraged to select a radial length that meets the lEe 62305-3
requirements for Type II lightning protection system.
_______________________________________________________________________________________________
780-34 Log #5
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-115
Delete asterisk:
4.14* Common Grounding Bonding of Grounded Systems.
There is no annex material referenced to this title (paragraph) – delete asterisk
_______________________________________________________________________________________________
780-35 Log #43
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-40
Delete text as follows:
"...due to the use of plastic pipe sections or other reasons, the"
Not necessary verbiage.
Printed on 9/18/2012
11
A2013/ROC/NFPA 780/Log #55/Figure A.4.13.8.1.2/Rec
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-36 Log #4
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-40
Revise text to read as follows:
4.14.6 Where bonding of the lightning protection grounding system, grounded media, and buried metallic conductors
has not been accomplished at a common point, interconnection shall be provided according to the following:
(1) Grounded media and buried metallic conductors shall be bonded to the lightning protection grounding system below
a height 12 ft. (3.6 m) vertically above the base of the structure.
(2) Grounded media and buried metallic conductors inherently bonded through construction to the lightning protection
grounding system shall not require further bonding.
(3) The continuous metal framework of a structure shall be connected to the lightning protection system (See 4.9.13
and 4.16 4.19).
(4) Main size lightning conductors shall be used for direct connection of grounded media and buried metallic
conductors to the lightning protection system.
(5) A ground bar designed for interconnection of building grounded systems shall have one connection to the lightning
protection system.
(6) A continuous metal water pipe system designed for interconnection of building grounded systems shall be
connected to the lightning protection system.
(7)* Interconnection to a gas line shall be made on the customer’s side of the meter.
(8)* Where galvanic corrosion is a concern or where a direct bond is prohibited by local code, an isolating spark gap
shall be permitted.
Reference in item 4.14.6 (3) should be to new section 4.19, not the old section 4.16.
Added asterisk to paragraph 4.14.6 (7) to designate reference for annex materials A.4.14.6 (7)
_______________________________________________________________________________________________
780-37 Log #67
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-42a
All value in text and formulas have to be changed to express "English" values first.
It was the decision of the 780 Committee that all numeric values were to be expressed with the
"English" Values, with the SI Values in parenthesis.
_______________________________________________________________________________________________
780-38 Log #6
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-42a
Delete asterisk:
4.15.1*Ground-Level Potential Equalization. Ground-level potential equalization shall be required in accordance with
Section 4.14.
Annex materials moving to paragraph A.4.14.2, so there is no longer Annex materials related to 4.15.1
(remove the asterisk)
Printed on 9/18/2012
12
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-39 Log #59
_______________________________________________________________________________________________
Richard Kithil, National Lightning Safety Institute
780-42a
Ref. Section 4.15.1.1 (now 4.18.1.1 ROP 780-42a, CP5) permitting conductors carrying 50,000°F.
Lightning next to potentially flammable materials is dangerous.
There is evidence that residential fires have been the result of such concealed conductors. Contact us
for photos and fire reports.
_______________________________________________________________________________________________
780-40 Log #46
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Revise text to read as follows:
The lightning protection system. Ddown conductors and other grounded media shall be interconnected with a loop
conductor at intermediate levels not exceeding 60 m (200 ft).
Not necessary.
_______________________________________________________________________________________________
780-41 Log #47
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Revise text as follows:
The lightning protection system. Ddown conductors and other grounded media shall be interconnected with a loop
conductor at intermediate levels not exceeding 60 m (200 ft).
Not necessary.
_______________________________________________________________________________________________
780-42 Log #7
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-42a
Revise text as follows:
4.16* Bonding of Metal Bodies. Metal bodies, not covered by other sections of this Standard, located outside or inside
a structure that contribute to lightning hazards because they are grounded or assist in providing a path to ground for
lightning currents shall be bonded to the lightning protection system in accordance with Section 4.21
.
Added asterisk (*) after 4.16 to designate Annex paragraphs which relate to this paragraph.
and
Reference at end changed from old section 4.21 (no longer exists) to 4.16.
Printed on 9/18/2012
13
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-43 Log #48
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Revise text as follows:
h = vertical distance between the bond being considered in question and the nearest lightning protection system bond
component.
"h" is a parameter that I have received many, many questions on. It appears to be unclear to the
reader/user.
_______________________________________________________________________________________________
780-44 Log #49
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Add diagram.
"h" is a parameter that I have received many, many questions on. It appears to be unclear to the
reader/user.
_______________________________________________________________________________________________
780-45 Log #50
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Revise text as follows:
FIGURE 4.16.3.1 Effect of Isolated (Nongrounded) (Ungrounded) Metallic Bodies, Such as a Window Frame, in
Nonconductive Media.
Change to terminology consistent with codes.
_______________________________________________________________________________________________
780-46 Log #79
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-42a
Revise text to read as follows:
4.19.2.2 Where such an exterior conductor is used, it shall be connected to the metal framework of the structure at
intervals not exceeding an average distance or 30 m ( 100 ft), as widely spaced as practicable around the perimeter of
the building, and at intervals not exceeding a distance of 45 m (150 ft) along a cross-run conductor.
Installers and inspectors have been applying the concept in the added text to the designs of structural
metal framed systems for many years. This change is an attempt to coordinate with standard industry practice.
Printed on 9/18/2012
14
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-47 Log #80
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-42a
Change the word "steel" to metal".
4.19.3.4 Bonding plates shall have bolt-pressure cable connectors and shall be bolted, welded, or brazed to the
structural steel metal framework so as to maintain electrical continuity.
Editorial change that was missed in the 2011 cycle.
_______________________________________________________________________________________________
780-48 Log #62
_______________________________________________________________________________________________
Matthew Caie, ERICO, Inc.
780-42a, 780-45
Revise text to read as follows:
Signal, data, and communications SPDs’ shall have a maximum discharge current ( ) rating of at least
10kA 8/ 20 us or greater when installed at the entrance.
Editorial comment - as its stated at least 10kA... then term or greater is redundant.
Printed on 9/18/2012
15
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-49 Log #28
_______________________________________________________________________________________________
Morris Kline, HMT Inc.
780-1a
Revise text as follows:
Chapter 7 Protection for Structures Containing Flammable Liquids - suggested title change
7.1.1.1 This chapter shall apply to the protection of structures containing flammable liquids.
7.1.2.1 Delete
7.1.2.2 Delete
7.1.3* Delete
7.2 through 7.2.5 Delete
7.3.1 Material and Installation. Metallic aboveground storage tanks are considered inherently grounded. The use of
conductors, strike termination devices, surge protection, and grounding connections are not required for lightning
protection and have been observed to introduce a hazard. The use of strike termination devices, lightning protection
masts and overhead ground wires on aboveground storage tanks is prohibited.
7.3.2 Delete
7.3.2.1 Delete
Figure 7.3.2.2 Delete
7.3.2.3 Delete
7.3.2.4 Delete
Figure 7.3.2.4 Delete
7.3.2.5 through 7.3.2.7.4 Delete
7.4.1 Metallic aboveground tanks at atmospheric pressure containing flammable vapors or liquids
7.4.1.2* External Floating-Roof Tanks. Needs to be reworded completely to address the situation of an owner operator
that operates their tanks in a drain dry situation on a frequent basis. A risk analysis indicates that shunts that are located
below the floating roof deck could add a hazard in this potential vapor area.
7.4.1.6 Reword to: Metallic Tanks with Nonmetallic Roofs. Metallic tanks with wooden or other nonmetallic roofs shall
not be considered self-protected.
7.4.1.6.1 through 7.4.1.6.4 Delete
7.4.1.7 Grounding Tanks. Metallic flat-bottom tanks resting on the ground need not be grounded by the use of external
grounding rods for the purpose of lightning protection. Grounding for other purposes is not addressed by this document.
7.4.1.7.1 and 7.4.1.7.2 Delete
7.4.2 Delete "That give off Flammable Vapors.
7.4.2.2 Aboveground nonmetallic tanks including an exposed tank roof shall not be used for storage of flammable
liquids.
The API Subcommittee on Aboveground Storage Tanks (SCAST) has reviewed the changes proposed
in this ROP and is considering removing any reference to NFPA 780 from API 650 and API 653 documents. Additionally,
they are moving forward to revise and improve the API RP 545 document that also addresses Lightning Protection.
_______________________________________________________________________________________________
780-50 Log #52
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-67
Renumber to Section 8.7 and adjust sub-paragraphs to the new number.
Section 8.7 is skipped in the new numbering.
Printed on 9/18/2012
16
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-51 Log #53
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-67
Change "8.7.1.1" to the proper reference.
None given.
_______________________________________________________________________________________________
780-52 Log #54
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-67
Change to Section 8.8 and 8.9.
None given.
_______________________________________________________________________________________________
780-53 Log #70
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-108
Edit text to comply with the Manual of Style.
Some text does not comply with the Manual of Style. Section 11.4.2.6 has a note without mandatory
language, making it Annex material. This section also adds another definition of Bonded (bonding) as 3.3a where one
already exists under Section 3.3.2. The committee needs to decide which definition it wants.
_______________________________________________________________________________________________
780-54 Log #18
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Add text to read as follows:
11.2.4 All requirements of 4.2 Materials. 4.3 Corrosion Protection. 4.4 Mechanical Damage or Displacement. 4.9.5
Conductor Bends. 4.13 Grounding Electrodes and 4.14 Common Grounding shall apply. except as modified by this
chapter.
Noted text was included in ROP-108 text, but omitted from published draft. Consistent with approved
ROP-108 text.
Printed on 9/18/2012
17
Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-55 Log #26
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Insert new paragraph 11.4.2.3 and renumber balance of section.
I
When raceway is installed by the directional bore, jack and bore or other drilling method the counterpoise
conductor shall be installed concurrently with the directional bore, jack and bore or other drilling method raceway,
external to the raceway or sleeve.
I Insert new paragraph A.11.4.2.3 and renumber balance of section.
'I
Compliance could be difficult with the requirements of this chapter when designing a new lighting system or
when replacing all or a portion of a lighting system at an existing airport. When existing pavement cannot be cut: !
raceway is typically installed under the pavement by the directional bore. jack and bore or other drilling method. When :
raceway is installed by a drilling method it is permissible to install the counterpoise conductor concurrent with the drilling
method raceway, external to the raceway or sleeve. This could result in the counterpoise conductor being wrapped
around the raceway in an unknown position relative to the raceway or cable being protected. The installation of the
counterpoise conductor is required to maintain the equipotential bonding of the overall lightning protection system. The
lightning protection afforded by this process is reduced; however, this manner of installation is more effective than
omission of the counterpoise conductor. This method is not recommended for projects where the pavement is being
overlaid or replaced. The counterpoise conductor should be placed prior to any paving operations in accordance with
the requirements of Chapter 11.
_______________________________________________________________________________________________
780-56 Log #19
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Add text to read as follows:
Note: Light base ground rod can be installed either through the bottom of the light base or exterior to the light base.
Note text for figure 11.4.2.6 is included in the draft ROP artwork and in the body of the draft ROP. The
note should be included only once in Figure 11.4.2.6. Consistent with approved ROP-108 text.
_______________________________________________________________________________________________
780-57 Log #14
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Change hatch patterns to gray scale in Figures 11.4.2.6, 11.4.3.2 and A.11.4.2 .7.5.
The hatch patterns at the current intensity tend to over shadow the details and dimensional lines.
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-58 Log #20
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
FIGURE 11.4.2.7 Raceways Installed Under Pavement, Raceways and Cables not Installed
Adjacent to the Full Strength Pavement Edge, . Fixtures Installed in Full Strength Pavement and Shoulder Pavement
and Optional Method of Edge Lights Installed in Turf (stabilized soils)iand Raceways and Cables Adjacent to Full
Strength Pavement Edge.
Original ROP text had a comma following edge instead of the period. Consistent with approved
ROP-108 text.
_______________________________________________________________________________________________
780-59 Log #15
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Figures 11.4.3.2 and A.11.4.2 .7.5, increase the size of the filled circle representing the
counterpoise conductor and the lines representing the area of protection as they are hard to see.
The counterpoise conductors and area of protection lines are difficult to distinguish from the
background.
_______________________________________________________________________________________________
780-60 Log #21
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
FIGURE 11.4.3.3 Multiple Counterpoise Conductor Installation Interconnection Plan View .
Consistent with approved ROP-108 text.
_______________________________________________________________________________________________
780-61 Log #22
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Add text to read as follows:
11.4.5.2* Grounding electrodes shall comply with all the requirements of 4.13.2 Ground Rods.
4.13.5 Radials. 4.13.6 Plate Electrode or Ground Plate Electrode, 4.13.7 Combinations. and
4.13.8 Grounding Electrode Selection Criteria. except as modified by this chapter.
Consistent with approved ROP-108 text.
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-62 Log #82
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc. / Rep. Harger Lightning & Grounding
780-109
Add new text
12.3.2 Strike termination devices shall be located at the ends of the uppermost edge or nearest support of solar panels
or panel arrays not to exceed 0.6 m (2 ft) from the end of the panel or array unless the uppermost edge or nearest
support is within a zone of protection.
Added text clarifies intent.
_______________________________________________________________________________________________
780-63 Log #83
_______________________________________________________________________________________________
Thomas R. Harger, Harger Inc.
780-109
Revise existing text as follows:
12.5 Grounding.
12.5.1 Ground Mounted Systems.
12.5.1.1 Systems that rely on the metallic structure to form part of the lightning protection system shall be grounded in
accordance with 4.13.4 utilizing a ground ring electrode encompassing the perimeter of each array.
12.5.1 .1.1 Combinations of other grounding electrodes in 4.13 shall be permitted.
12.5.1.1 .2 Ground ring electrodes of adjacent ground mounted systems within 25 ft (7 .6 m) shall be interconnected.
12.5.1.2 Systems that rely on the metallic structure to form parts of the lightning protection system shall be made
electrically continuous by the methods specified in 4.16.3.
12.5.1.3 For solar arrays that do not rely on the metallic structure to form part of the lightning protection system, each
separate row or structure shall be bonded at one location direct to the ground ring electrode.
12.5.1.4 Solar arrays that do not rely on the metallic structure to form part of the lightning protection system shall be
made electrically continuous by means of bonding in accordance with the NEC.
12.5.2 Roof Mounted Systems.
12.5.2.1 Solar arrays shall be bonded in accordance with 4.20.3.
12.5.2.2 Solar arrays shall be made electrically continuous by means of bonding in accordance to the NEC.
12.5.2.3 If the structure forms part oL or is within the required separation distance from the lightning protection system.
the metallic structure of the system shall be made electrically continuous in accordance with Chapter 4.
12.5.2.4 Roof conductors interconnecting strike termination devices protecting roof mounted solar panel shall be
provided with down conductors and grounding electrodes in accordance with Chapter 4.
12.5.2.5 Roof conductors interconnecting strike termination devices protecting roof mounted solar panels shall be
connected to the structure lightning protection system in accordance with Chapter 4.
Added text in 12.5.1 permits the use of combinations of electrodes to supplement the ring electrodes
and requires that adjacent systems be interconnected.
Added text in 12.5.1.2 clarifies how to make the structures "electrically continuous".
Added text in 12.5.2.4 addresses roof mounted systems mounted on structures without lightning protection systems.
Added text in 12.5.2.5 addresses roof mounted systems mounted on structures with lightning protection systems.
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-64 Log #61
_______________________________________________________________________________________________
Matthew Caie, ERICO, Inc.
780-109
Revise text to read as follows:
Systems that rely on the comprising of a metallic structure to form part of the lightning protection system shall
be grounded in accordance with Section 4.13.4 utilizing a ground ring electrode encompassing the perimeter of each
array.
In review of Section 12.5.1 its clear that a ground ring electrode is desired for all metallic structure
systems when lightning protection is to be applied. The above clarifies this and helps with the flow thereafter for metallic
structures that either form or don’t form part of the lightning protection system.
_______________________________________________________________________________________________
780-65 Log #37
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-21
Add new text to read as follows:
The "grounded point" is the point of connection of the overhead ground wire to the down conductor, at the
top of the mast.
The down conductor is essentially the "grounded point" since it is directly connected to the ground loop
or grounding electrode, typically by thermo-weld. Inclusion of the additional height of masts will drive the side flash
calculation, "0," to a distance that will raise the poles to a height which results in no added protection. The added
expense (both installation and testing) of taller poles contributes no added protection.
_______________________________________________________________________________________________
780-66 Log #10
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-115
Revise text to read as follows:
When separate but adjacent buildings and/or facilities are interconnected directly (not through a utility)
by electric, CATV, CCTV, data, or communications wiring, the grounding systems of those buildings should be directly
interconnected to each other using a main-size conductor. The need for this interconnection can be eliminated by the
use of fiber optic cable, shielded wire, wire run in grounded metallic conduit, or redundant surge protection (SPD¡¯s
installed at entrance /exit of both buildings/facilities).
Corrected Annex paragraph number to the new paragraph location
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-67 Log #8
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-117
Revise text to read as follows:
There could be installations where multiple sections of piping and associated junctions exist
between the gas meter/regulator and the entrance of the line to the structure. Such junctions can create increased
impedances at frequencies that are associated with overvoltages. Where there is internal piping that could be
susceptible to overvoltages, care should be taken to ensure that the interconnection of the lightning protection grounding
system is made to pipe sections that will not increase the impedance between the pipe and the grounding section. This
could be accomplished by connection to the last section of the pipe entering the structure. This interconnection could be
made either external or internal to the structure. [ROP-40]
Definitions in the NEC (NFPA 70) and 780 for bonding or bonded, grounded or grounding and grounding
electrode are similar. The actual standards sections that define what constitutes these various items point to differences
in application, equipment, and requirements.
NEC paragraph 250.50 (Grounding Electrode System) requires all electrodes present at each building or structure be
bonded together to form the grounding electrode system. This coordinates to the requirements of Section 4.14. The
differences occur in NEC Section 250.52 which describes grounding electrode devices not shown in Section 4.13.
Grounding electrode devices described in Section 250.52, but not referenced in this document include:
(1) 250.52 (A) (1) 10 ft. of metallic underground water pipe extending from the structure in contact with earth
(2) 250.52 (A) (2) (1) The metal frame of the structure in contact with earth
(3) 250.52 (A) (3) (2) The concrete encased electrode described as #4 AWG would need to be a main size conductor
per Paragraph 4.13.3.2
(4) 250.52 (A) (4) The ground ring electrode not smaller than #2 AWG is acceptable for Class I, but would not be
acceptable for Class II (See Table 4.1.1.1.2)
(5) 250.52 (A) (5) Pipe electrodes shown under section (a) are not included. Rod electrodes described in (b) as zinc
coated steel are not covered (4.13.2.5)
(6) 250.52 (A) (6) Other listed electrodes would need to comply with the various sections of 4.13
(7) 250.52 (A) (7) Plate electrodes would need to comply with 4.13.6
(8) 250.52 (A) (8) “Other local metal underground systems or structures” are not referenced as grounding electrodes in
this Standard
The lightning protection system designer must be familiar with these differences for coordination of interconnection with
other building grounding electrodes or the structural grounding electrode system as required by paragraph 4.14.3.
[ROP-117]
The first paragraph is moved to the proper location under another comment.
The balance of the information shown under new A.4.14.3 needs to begin with the correct paragraph reference
(added).
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-68 Log #9
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-40
Revise text to read as follows:
There could be installations where multiple sections of piping and associated
junctions exist between the gas meter/regulator and the entrance of the line to the structure. Such junctions can create
increased impedances at frequencies that are associated with overvoltages. Where there is internal piping that could be
susceptible to overvoltages, care should be taken to ensure that the interconnection of the lightning protection grounding
system is made to pipe sections that will not increase the impedance between the pipe and the grounding section. This
could be accomplished by connection to the last section of the pipe entering the structure. This interconnection could be
made either external or internal to the structure.
Corrected Annex reference to proper paragraph A.4.14.6 (7).
_______________________________________________________________________________________________
780-69 Log #68
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-118
Edit text to comply with the Manual of Style.
The text does not comply with the Manual of Style.
As modified by the committee the English value should be listed with SI values in parentheses following those values.
5 feet should be 5 ft (1.52 m) 3/16" should be 3/16 in. (4.8 mm).
_______________________________________________________________________________________________
780-70 Log #11
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-42a
Revise text to read as follows:
For structures 18 m (60 ft) or less in height, a loop conductor should be provided for the
interconnection of all grounding electrodes and other grounded media. Regardless of the building height, ground loop
conductors should be installed underground in contact with earth. Ground-level potential equalization allows use of a
ground ring electrode as a ground loop conductor. A ground ring electrode conforming to 4.13.4 can be utilized for the
ground loop conductor.
Annex paragraph fits best with new paragraph 4.14.2 of document.
Printed on 9/18/2012
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-71 Log #12
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-42a
Revise text to read as follows:
In addition to the bonding of metal bodies, surge suppression should be provided to protect power,
communication, and data lines from dangerous overvoltages and sparks caused by the lightning strikes. (See Annex C
for a discussion of bonding and an understanding of problems often encountered.)
This annex material is referenced to section 4.16.3 covering “isolated (nongrounded) metallic bodies”.
I will not argue that service lines for communication or power are ungrounded, but I believe the user would be more
likely to access this information if it is keyed to paragraph 4.16 – Bonding of Metal bodies
_______________________________________________________________________________________________
780-72 Log #13
_______________________________________________________________________________________________
Harold VanSickle, III, Lightning Protection Institute
780-42a
Revise text to read as follows:
See Annex C for a technical discussion of lightning protection potential-equalization bonding.
Potential equalization is moved in the new version from 4.19 to 4.16.
_______________________________________________________________________________________________
780-73 Log #51
_______________________________________________________________________________________________
Joanie A. Campbell, US Department of the Air Force
780-42a
Add new text to read as follows:
Surge protection alone is not intended to prevent or limit physical damage from a direct lightning strike to a
facility or structure. Rather, it is intended to defend against indirect lightning effects imposed upon the electrical services
to a structure as part of a coordinated lightning protection system installed in accordance with the requirements of this
standard. However, if calculations indicate that LPS is required, but there is no significant dollar value to facility
contents, surge suppression may meet the requirement for LPS.
Specifically, administrative facilities and dormitories only require protection for electronic devices.
Surge suppression would meet the requirement for LPS if a tiered system is provided. Surge suppression simply at the
main distribution panel would NOT meet the requirement for LPS unless it is the only panel for the facility. I have not yet
performed a calculation where LPS is not required. I even inserted 25 SF for a fictional building and it came out as being
required.
_______________________________________________________________________________________________
780-74 Log #69
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-123
Values are to be changed expressing the "English" values first.
It was the decision of the 780 Committee that all numeric values were to be expressed with the
"English" Values, with the SI Values in parenthesis.
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-75 Log #16
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Correct spelling in Figures A.11.1.1(a) and A.11.1.1(b). Change from "elctrode" to "electrode" in
two places on each figure.
Correct spelling.
_______________________________________________________________________________________________
780-76 Log #23
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
Revise text to read as follows:
A.11.4.2.6 This subsection addresses items installed in turf adjacent to the full strength pavement edge. Items within
4.6 m (15 ft) of the full strength pavement edge could be considered adjacent to the full strength pavement edge for the
purpose of this subsection. The exact routing of the counterpoise conductor could be subject to field conditions such as
rock or other obstructions. The counterpoise conductor should be routed as close as practical to the midpoint between
the full strength pavement edge and itt:)m being protected .
Insert space between "strength pavement" in third line of text. Consistent with approved ROP-108 text.
_______________________________________________________________________________________________
780-77 Log #24
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
FIGURE A.l1.4.2.7.5 Are Area of Protection.
Correct spelling of word "area". Consistent with approved ROP-108 text.
_______________________________________________________________________________________________
780-78 Log #25
_______________________________________________________________________________________________
Carl S. Johnson II, AVCON, Inc.
780-108
A.11.4.5.2 The often accepted earth resistance value of 25 ohms should not be interpreted as
satisfactory for all installations. refer to Annex B.4.4. Reduced earth resistance values could be necessary to provide
effective lightning protection where the lightning risk assessment is high. A.11.4.1 could be used to determine if reduced
earth resistance is necessary for protection of the airfield lighting system. The AHJ could define the required grounding
electrode , earth resistance value .
Delete hard return after the word "protection" and insert space so sentence reads correctly. Consistent
with approved ROP-108 text.
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-79 Log #58
_______________________________________________________________________________________________
Richard Kithil, National Lightning Safety Institute
780-126
Delete: "TENKA peak current represents 91 percent of all lightning events."
Add: About 95% of negative first studies exceed 14 kA, 50% exceed 30 kA, and 5% exceed 80 kA.
Reference: Rakov, V.A.: 2012, Journal Lightning Research, 2012, 4 (Suppl L:m2) 3-11.
_______________________________________________________________________________________________
780-80 Log #57
_______________________________________________________________________________________________
Mitchell Guthrie, Independent Engineering Consultant
780-125, 780-126
Change 46m back to 45m in the body of the text and associated figure.
The change is not necessary based on the action taken on ROP 780-1a that indicates English units
are the dominant values. This change makes NFPA 780 different from any other standard in the world as all others
reference 45 meters and 150 feet as the value for ordinary or Type III rolling sphere radius.
_______________________________________________________________________________________________
780-81 Log #27
_______________________________________________________________________________________________
David E. McAfee, B&W Technical Services Y-12, LLC
780-138
Replace the Figure in the ROP that uses Fl/sq-mi/yr with the attached Figure that uses Fl/sq-m/yr.
Flashes/sq-milyr and Flashes/sq-m/yr
*** Insert figure here****
All of the units for the Risk Assessment Methods in Annex L utilize Fl/sq-m/yr NOT Fl/sq-mi/yr. The
attached figure utilizes the correct units.
_______________________________________________________________________________________________
780-82 Log #2
_______________________________________________________________________________________________
John F. Bender, UL LLC
780-139
Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062-2096.
, Third Edition, 2006, Revised 2011.
ANSI/UL 1449,
Update the referenced standard to the most recent edition.
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Report on Comments – June 2013
NFPA 780
_______________________________________________________________________________________________
780-83 Log #3
_______________________________________________________________________________________________
John F. Bender, UL LLC
780-1
Revise text as follows:
ANSI/UL 497,
ANSI/UL 497A,
ANSI/UL 497B,
2008.
ANSI/UL 497C,
UL 497E,
, 2001, Revised 2009.
, 2001, Revised 2008.
, 2004, Revised
, 2001, Revised 2008.
, Edition 4, 2011.
This proposal is being re-submitted with updated revision dates as indicated, with the request that the
committee reconsider adding such revision dates, in addition to the initial publication date of the standard, to reflect the
most recent technical update of the standard as revised from time to time by the UL Standard Technical Panel
responsible for each of the respective standards. Reference to the initial publication date of the standard and any
subsequent revision date for that standard is consistent with almost all other NFPA Standards, such as NFPA 72 and
NFPA 101 as two prime examples.
_______________________________________________________________________________________________
780-84 Log #71
_______________________________________________________________________________________________
Stephen Humeniuk, Warren Lightning Rod Company / Rep. United Lighting Protection Association
780-109
Edit text to comply with the Manual of Style.
Section 12.3.4.1 does not meet the Manual of Style. It mandates "compliance with one of the
following," then only lists Section 12.3.4.1.1. There is no Section 12.3.4.1.2. Either add other options or rewrite the text.
Printed on 9/18/2012
27