:: DESIGN ::
PoE and other technologies are pushing
powered-device wattages ever-higher
Two new flavors of IEEE-specified Power over Ethernet
explained, “Four-pair powering is
are in the works, and non-IEEE technologies are
supported in the latest PoE standard,
already common. What does it mean for cabling?
and uses all four pairs of Ethernet cable to enable up to 60 W of DC [direct
current] power to be delivered over
BY PATRICK McLAUGHLIN
a single cable using current levels
It has been said many times, in live
capabilities. IEEE 802.3af (commonly
of 600 mA … To enable these pow-
and online seminars, that typically
called simply “PoE”) specifies the gen-
ering levels, the IEEE specifications
industry standards are at least a
eration of up to 15.4 watts of power,
changed the definition of a PD so that
step or two behind the latest tech-
with 12.9 watts delivered to the pow-
it considers the PD the power inter-
nological developments—catching
ered device (PD). And IEEE 802.3at
face, as opposed to the whole de-
up the best they can but almost al-
(commonly called “PoE Plus,”) spec-
vice being powered. This means that
ways trailing, not leading, the ca-
ifies the generation of up to 34.2
there can now be two power inter-
pabilities being made available to a
watts of power, with 25.5 watts deliv-
faces, each taking 25.5W, in the same
market. That refrain holds true to-
ered to the PD.
box. Nothing precludes these from
day for the technologies that enable
Ty Estes, director of marketing at
being connected, one over two pairs
the powering of network devices us-
Omnitron Systems Technology Inc.
using lines 1, 2, 3, and 6 and the other
ing twisted-pair copper cabling as
(www.omnitron-systems.com), ex-
two over the two pairs using lines 4,
the medium that carries appropriate
plained, “The IEEE standard for
5, 7, and 8. This is what makes it pos-
wattage to those powered devices.
60W, also known as PoE++, is cur-
sible to double the standard 802.3at-
Collectively, the technologies that
rently in development with the IEEE
2009 maximum of 25 W and go up
enable this type of device powering
802.3bt Type 3 Work Group, and is
to 51 W while fully complying with
commonly are referred to as Power
projected to be ratified in early 2017.
the standard.”
over Ethernet (PoE). As we published
In lieu of a 60W PoE standard, equip-
in an article last year, the use of that
ment manufacturers have doubled
debuted its Universal Power over
term has drawbacks as well as ben-
the 802.3at PoE+ capability on four
Ethernet (UPOE) system, which deliv-
efits (“Why the industry needs a
pairs, and powered all eight pairs to
ers 60 W to PDs. At the time of that an-
PoE Logo Program,” October 2014).
achieve 60 watts.”
nouncement, Cisco’s Catalyst 4500E
Nonetheless, the term PoE is widely
In 2011, Cisco (www.cisco.com)
switch was the infrastructure that
used as an inclusive term, and we
Going beyond IEEE
housed the 60-watt UPOE capabil-
will use it in this article as well.
To Estes’s point, in 2010—the year
ity. The company said target applica-
after IEEE 802.3at was published—
tions for UPOE included IP phones,
and Electronics Engineers (IEEE;
Microsemi’s (www.microsemi.com)
personal telepresence systems, com-
www.ieee.org) has published two
director of product management
pact switches and wireless access
sets of specifications defining these
and product marketing, Sani Ronen,
points. Others also have pointed out
To date, the Institute of Electrical
Reprinted with revisions to format, from the June 2015 edition of CABLING INSTALLATION & MAINTENANCE
Copyright 2015 by PennWell Corporation
::
design
::
that some IP cameras can benefit from
overall power consumption does not
the Ethernet Technology Summit, but
more power than that afforded by IEEE
exceed 100 W.”
did obtain the visuals of the presenta-
802.3at. Specifically, cameras that re-
Feldman’s comment broaches the
tion that Straka delivered. The sum-
side outside and require tempera-
topic of cabling performance level and
mary that follows is derived from those
ture-control in the form of blowers and
support of PoE/PoH. That topic has
visuals. The table within this arti-
heaters are power-hungry, and are of-
been, and remains, the subject of sig-
cle also is reproduced from Straka’s
ten referenced as the types of network
nificant study as the IEEE moves for-
presentation.)
devices pushing the need for higher
ward with its latest PoE specifications.
power delivered via cabling.
As Estes mentioned, IEEE 802.3bt is
dressed the extent to which heat rise
Omnitron provides an array of me-
Among other topics, Straka ad-
under development. Within IEEE no-
within cable bundles could have del-
dia converters, including models that
menclature, the 802.3af specification is
eterious effects on cabling system
provide PoE. In that vein, Estes noted,
known at “Type 1” PoE, and 802.3at is
performance when those cables are
“In addition to the increasing power
known as “Type 2.” The current effort,
carrying 100-watt PoE. Straka’s pre-
required by PoE devices, the 100-me-
802.3bt, is likely to include a “Type 3”
sentation noted, “Cable tempera-
ter distance limitation of UTP cabling
and “Type 4” PoE. Type 3 will spec-
ture matters because some tempera-
is a challenge in large facilities like
ify a current level up to 600 milli-
ture rise will increase cable insertion
airports, arenas, building complexes,
Amps (mA) and 49 watts at the pow-
loss and may create bit errors; extreme
and government facilities. High-power
ered device, while Type 4 will specify
temperature increase above the cable
media converters can power the lat-
a 1,000-milliAmp (1 Amp) current level
operating range can damage the ca-
est generation of 60-watt devices that
and 96 watts at the powered device.
ble.” Cable manufacturers, he noted,
have emerged onto the market, and extend distances with fiber cabling.”
Type
Standards
PoE
IEEE 802.3af
(802.3at Type 1)
350 mA
2
12.95W
2003
IEEE 803.3at
Type 2
600 mA
2
25.5W
2009
PoE++
Proposed IEEE
802.3bt Type 3
600 mA
4
49W
Expected
2016-2017
PoE++
Proposed IEEE
802.3bt Type 4
1000 mA
4
96W
Expected
2016-2017
Non-PoE
standard-based
Cisco UPOE
600 mA
4
60W
No official
ratification
Non-PoE
standard-based
HDBase-T
1000 mA
4
96W
No official
ratification
In 2011, the same year Cisco introduced UPOE, the HDBase-T Alliance
(www.hdbaset.org) released the
Power over HDBase-T (PoH) specification, which defines the delivery of
up to 100 watts of power over a single cable, up to 100 meters. At that
time Daniel Feldman, vice president
with Microsemi, explained, “Core
PoE technology has been enhanced
for the PoH specification to include
PoE+
Max
Energized Power at Standard
Current
Pairs
Device
Ratified
a higher current of almost 1 Amp for
every two pairs, with an appropriate
Cabling implications
will provide users with information
three-event classification that identi-
In April at the Ethernet Technology
about the maximum bundle size that
fies PoH power sourcing equipment
Summit (www.ethernetsummit.com),
can meet the 15-degree tempera-
[PSEs]. This enables PoH technol-
Frank Straka, product development
ture rise limit recommended in the
ogy to transfer up to 100 w of contin-
manager with Panduit (www.panduit.
TIA TSB-184 document, “Guidelines
uous DC power, per port, from one
com), addressed the issue in a presen-
for Supporting Power Delivery Over
side of the HDBase-T link to the other.
tation titled “100W PoE++’s Impact
Balanced Twisted-Pair Cabling.”
Unlike in PoE, where the PD must as-
on Infrastructure.” Just as 802.3af
Straka stated that the equation that
sume a worst-case cabling infrastruc-
has become known as “PoE” and
should be used when planning for
ture at all times, PoH enables the PD
802.3at as “PoE Plus,” 802.3bt is being
higher-power PoE is: cable tempera-
to identify the cable length/resistance
dubbed “PoE Plus Plus” in some cir-
ture rating is less than or equal to the
and draw more power, as long as the
cles. (Note: This author did not attend
ambient temperature plus 15.
He pointed out that of PoE and
are few, if any, options,” he contin-
company’s senior product manager for
PoE Plus, Category 5e, 6, and 6A ca-
ues. “To appropriately address the in-
copper systems, Grayling Love, dis-
bles all complied with TSB-184’s
creased temperature rise, one could be
cussed several of the cabling issues
15-degree maximum temperature
confined to using Category 6A [UTP]
addressed in this article. Concerning
rise when tested in bundles of 100
or Category 6A F/UTP. The limiting
connection reliability, Love noted,
cables. However, during testing of
factor of many devices, especially IP
“When a patch cord is unplugged
802.3bt pre-standard technology, only
cameras, nurse call systems, building
while the connection is charged, an
Category 6A cables stayed within the
management controls and point-of-sale
electrical arc will occur between the
15-degree recommendation. A couple
is power consumption, not data. This
connector and the plug. While there is
recommendations to take away from
places a difficulty on premises design-
no immediate damage (and the arc is
these test findings are that Category
ers to justify the use of higher category
not dangerous to users), the integrity of
5e and 6 runs should be assembled in
cabling or the need to pull a power
the connection can become weakened
bundles of fewer than 100 cables. And,
source onto a location.”
over numerous disconnections. To add
as one line in Straka’s presentation
Portions of the technical paper dis-
extra protection and longevity to the
stated, “If thinking of running PoE++,
cuss and support the use of Category
life of the connection, Leviton recom-
Category 6A cabling is recommended.”
6 cable designed specifically for sup-
mends using connectors with 50-µm
porting higher-power PoE applications.
gold-plated tines (as specified by TIA
concerning the type of cabling that
“There are real benefits to using spe-
standards), as well as designs that dis-
will adequately support IEEE 802.3bt,
cially designed PoE cabling with prop-
tance the connection point between
and the physical placement and layout
erties such as larger, lower-gauge con-
the connector tines and plug from the
of that cabling. The TIA also is in the
ductors and higher temperature cable
arcing damage.” Love also referenced
process of revising TSB-184 to address
ratings for the majority of PoE applica-
the IEC 60512-99-001 standard cov-
802.3bt support.
tions,” Kusuma says. “Aside from hav-
ering connectors for electronic equip-
ing the confidence that the cable will
ment. “High-quality connectivity is es-
Examining options
withstand higher temperature opera-
sential for attaining the performance,
In a recently published technical pa-
tions and generate lower temperatures,
reliability, and flexibility needed in to-
per titled “Power Over Ethernet:
energy savings and efficiency are also
day’s network operations,” he added.
A Consumer-centric Development
considerations when deploying a large-
Perspective,” General Cable (www.
scale PoE infrastructure.”
Much remains to be determined
generalcable.com) communica-
Straka’s presentation at the
In the case of powering network
devices with upwards of 100 watts of
DC, industry standards may indeed be
tions-products engineer Roy Kusuma
Ethernet Technology Summit also ad-
a step or even two steps behind the
also addressed temperature-rise con-
dressed the phenomenon of arcing,
technologies being brought to market.
siderations in cable bundles. In the pa-
or sparking, that can occur on twist-
But the testing and investigation go-
per Kusuma points out, “In many cases
ed-pair cabling contacts when a plug
ing into the standardization process—
a large cable bundle may be present
is removed from a jack. “Arcing dam-
within the IEEE as well as the TIA—
under the floors, behind walls or en-
age may prevent data transmission
are for the purpose of ensuring, to the
closed in an insulated space. In the
through the plug and jack,” the pre-
extent possible, that an installed stan-
last circumstance, the heat rise figures
sentation stated plainly. Additionally,
dard-compliant system can be relied
are significantly worse, with numbers
it said, “Connectors should meet IEC
upon as an enabling infrastructure for
as high as 50 degrees Celsius above
60512-9-3 and IEC 60512-99-001 to en-
data and power delivery. The stan-
ambient temperatures for the typical
sure that when (not if) arcing occurs, it
dards currently under development are
worst-case Category 5e construction.
will not damage the critical plug-and-
no exception. When ultimately pub-
jack mating point where the plug is
lished, these standards will guide the
fully engaged.”
installation of powered devices, power
“Currently, in applications where
higher power usage is expected in excess of 50 watts, yet higher data transmission rates are not required, there
In a post to Leviton’s blog (blog.
leviton.com) in January 2015, the
sourcing equipment, and cabling systems around the world. ::