ARC FLASH PROTECTION AND
SAFETY MEASURES
September 2010
Introduction
Hazards of Electrical Energy
Electrical Safety Program
Safety-Related Work Practices
Electrical Safety Procedures
Presented By:
Ken Schmerber, MS, CIH, CSP
Principal EHS Consultant
Hellman & Associates, Inc.
303-384-9828
[email protected]
INTRODUCTION
• OSHA’s 29 CFR 1910.332(a) - Requires training
when employees face a risk of electric shock that
is not reduced to a safe level by the electrical
installation requirements of 1910.303 through
1910.308.
• OSHA’s 1926.416(a)(1) - No employer shall
permit an employee to work in such proximity to
any part of an electric power circuit that the
employee could contact the electric power circuit
in the course of work, unless the employee is
protected against electric shock by de-energizing
the circuit and grounding it or by guarding it
effectively by insulation or other means.
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INTRODUCTION
• To be Considered a Qualified Person:
ƒ Safety-related work practices that pertain to their job
assignments.
ƒ The skills and knowledge necessary to:
¾ Distinguish exposed live parts from other parts of electric
equipment; and
¾ Determine the nominal voltage of exposed live parts.
ƒ Appropriate clearance distances for the corresponding
voltages to which they will be exposed.
ƒ Construction and operation of the equipment and the
hazards involved.
ƒ Specific hazards associated with electrical energy.
ƒ Relationship between electrical hazards and possible
injury.
ƒ Applicable emergency procedures.
INTRODUCTION
• Regulations/Standards (≥ 50 Volts):
ƒ OSHA 29 CFR 1910, Subpart S, Electrical
¾
¾
¾
¾
¾
1910.331, Scope
1910.332, Training
1910.333, Selection and Use of Work Practices
1910.334, Use of Equipment
1910.335, Safeguards for Personal Protection
ƒ National Fire Protection Association (NFPA) 70E,
Standard for Electrical Safety in the Workplace, 2009
Edition
¾
¾
¾
¾
Chapter 1 - Safety-Related Work Practices
Chapter 2 - Safety-Related Maintenance Requirements
Chapter 3 - Safety Requirements for Special Equipment
Annexes A - O
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INTRODUCTION
• NFPA Chapter 1, Safety-Related Work Practices
ƒ Article 100 - Definitions
ƒ Article 110 - General Requirements for Electrical SafetyRelated Work Practices
ƒ Article 120 - Establishing an Electrically Safe Work
Condition
ƒ Article 130 - Work Involving Electrical Hazards
INTRODUCTION
OSHA
Reference
NFPA
Subpart S NFPA 70E
Chapter 1
Working on Live Parts
√
√
Qualified Person/Training
√
√
Approach Boundaries ALL
Work
Personal Protective
Equipment
√
Refers to
Subpart I
Hazard/Risk
Category
Electrical Safety Program
√
Energized Electrical Work
Permit
√
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INTRODUCTION
HAZARDS OF ELECTRICAL ENERGY
Hazards include:
ƒ Shock;
ƒ Electrocution;
ƒ Arc Flash/Blast; and
ƒ Burns.
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HAZARDS OF ELECTRICAL ENERGY
• Why is arc flash dangerous?
ƒ An arc is a source of intense heat, light, sound, and
pressure!
¾Colorado in July/August: 100 °F
¾Surface of the Sun: 8,540 °F
¾Arc at arc terminals: 35,540 °F
HAZARDS OF ELECTRICAL ENERGY
• Physical Effects of Arc Blast
ƒ Metal vapor and air expand very rapidly due to arc
heating.
ƒ Pressure wave (~740 mph; 2,000 psi; ~ 165 dB) knocks
worker away from arc:
¾
¾
¾
¾
¾
¾
Good: removes personnel from heat source
Bad: removes personnel from ladder
Eardrum rupture
Blindness
Lung damage
Death!
ƒ Molten metal droplets:
¾ Can ignite clothing
¾ Cause burns
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HAZARDS OF ELECTRICAL ENERGY
How hazardous can it be?
HAZARDS OF ELECTRICAL ENERGY
• Annual Preventative Maintenance Incident
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HAZARDS OF ELECTRICAL ENERGY
• Live Breaker Replacement Incident
HAZARDS OF ELECTRICAL ENERGY
• Breaker Racking
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ELECTRICAL SAFETY PROGRAM
• General
ƒ Implement overall program that is appropriate to manage
the degree of hazard
ƒ Electrical safety procedures are one component
ƒ LO/TO also plays a critical role
• Safe Work Procedures
• Hazard Analysis
ƒ Coordination Study
ƒ Shock and Arc-Flash Analysis
• Job Briefing
• Personal Protective Equipment
• Training
• Auditing
ELECTRICAL SAFETY PROGRAM
OSHA 29 CFR 1910.333
• Safety related work practices shall be employed to
prevent electric shock or other injuries resulting from
either direct or indirect electrical contact.
• Live parts to which an employee
may be exposed shall be
deenergized before the
employee works on or near
them, unless the employer can
demonstrate that deenergizing
introduces additional or
increased hazards or is
infeasible.
• Verification that equipment is
deenergized can be hazardous.
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ELECTRICAL SAFETY PROGRAM
• When is it acceptable to work on energized
equipment?
ƒ When it involves:
¾
¾
¾
¾
Interruption of life support systems;
Deactivation of emergency alarm systems;
Shutdown of hazardous location ventilation; and
Removal of illumination.
ƒ Or is infeasible:
¾ Diagnostics and testing (e.g., start-up and troubleshooting);
and
¾ Part of continuous process segment.
ELECTRICAL SAFETY PROGRAM
• Hazard Analysis
ƒ Coordination Study
ƒ Electrical Hazard Analysis
¾ Shock Hazard
™ Process described in NFPA 70E 130.2, Approach Boundaries
to Energized Electrical Conductors or Circuit Parts
¾ Arc Flash Hazard
™ Process described in NFPA 70E 130.3, Arc Flash Hazard
Analysis
™ Alternative is to use the PPE requirements in NFPA 70E
130.7(C)(9). The table can be used if system meets the
limitations in the Note section at the end of the table.
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ELECTRICAL SAFETY PROGRAM
• Hazard/Risk Evaluation Procedure
ELECTRICAL SAFETY PROGRAM
• Table 130.7(C)(9), Hazard/Risk Classification
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ELECTRICAL SAFETY PROGRAM
• Table 130.7(C)(9), Notes
ELECTRICAL SAFETY PROGRAM
• Table 130.7(C)(10), PPE
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ELECTRICAL SAFETY PROGRAM
• Table 130.7(C)(10), Notes
ELECTRICAL SAFETY PROGRAM
• Table 130.7(C)(11), Protective Clothing
Characteristics
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ELECTRICAL SAFETY PROGRAM
• Annex D, Incident Energy and Flash Protection
Boundary Calculation Methods
ELECTRICAL SAFETY PROGRAM
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ELECTRICAL SAFETY PROGRAM
• Equipment shall be field marked with a label
containing the available incident energy or
required level of PPE.
ELECTRICAL SAFETY PROGRAM
• Procedures (Routine)
ƒ Purpose of task
ƒ Qualifications and number of employees involved
ƒ Hazardous nature and extent of task
ƒ Limits of approach
ƒ Safe work practices to be utilized
ƒ Required PPE including insulating materials and tools
ƒ Electrical diagrams
ƒ Equipment details
ƒ Reference data
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ELECTRICAL SAFETY PROGRAM
• Job Briefing Form (Non-Routine)
ELECTRICAL SAFETY PROGRAM
• Energized Electrical Work Permit (Non-Routine)
ƒ Used when an electrical system cannot be placed in an
electrically safe work condition.
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SAFETY RELATED WORK PRACTICES
• LOTO
• Approach boundaries
• PPE and inspection
• Others
SAFETY RELATED WORK PRACTICES
• Approach Boundaries and PPE
ƒ Shock Protection
¾ Limited;
¾ Restricted; and
¾ Prohibited.
ƒ Flash Protection
¾ Distance at which the incident energy is 1.2 cal/cm2 (i.e.,
point at which second degree burns may occur).
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SAFETY RELATED WORK PRACTICES
Limits of Approach (Figure C-1-2.4)
SAFETY RELATED WORK PRACTICES
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SAFETY RELATED WORK PRACTICES
• Personal Protective Equipment
SAFETY RELATED WORK PRACTICES
• Use the left hand rule
• Open cabinets from hinged side
• Ensure there is adequate illumination
• No blind reaching
• Do not use over current protection devices as
switches
• Use shielding for enclosed spaces
• No use of conductive materials or equipment
such as metal ladders and apparel
• Housekeeping
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ELECTRICAL SAFETY PROCEDURES
ELECTRICAL SAFETY PROCEDURES
• Required PPE
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ELECTRICAL SAFETY PROCEDURES
• Procedure
SUMMARY
• OSHA and NFPA 70E
ƒ ≥ 50 V
ƒ Qualified Worker
• Hazards of Electrical Energy
ƒ Shock
ƒ Arc Flash
• Electrical Hazard Analysis
ƒ Determines PPE level
• Safety-Related Work Practices
ƒ Work deenergized
ƒ LOTO
ƒ PPE if working energized
• Electrical Safety Program
ƒ ESPs
ƒ Energized Work Permit
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