|Safety -- NFPA 70E: the “how’ of working around electricity safely|
|Issue Archives - July August 2010 issue|
by John Boyle
Many workers and engineers are familiar with the phrase, “NFPA 70E,” but few understand what the standard offers in electrical protection. The National Fire Protection Association’s NFPA 70E addresses electrical safety requirements for employees during installation, operation, maintenance and demolition of all types of electrical equipment.
NFPA 70E covers safety-related work practices, maintenance, special equipment requirements and installation. It focuses on protecting people and identifies requirements that provide a workplace free of electrical hazards.
OSHA bases its electrical safety mandates, found in Subpart S part 1910 and Subpart K part 1926, on information in NFPA 70E. NFPA 70E is related to the National Electrical Code (NEC), which describes how to design and install safe electrical systems.
NFPA 70E is the tool that illustrates how an employer might comply with OSHA standards. The relationship between the OSHA regulations and NEC may best be described as being the “shall” and NFPA 70E being the “how.”
NFPA 70E includes…
NFPA 70E applies to all workplaces such as factories, hospitals and even super stores. It is most often enforced on construction sites and in industrial plants. The NFPA 70E standard covers hazards such as electric shock/ electrocution, arc flash (electrical flame/fire) and arc blast (high-energy electrical explosion).
Safe electrical work strategies
NFPA 70E outlines two approaches for ensuring safe electrical work:
Turn off the power. NFPA 70E mandates that whenever possible, electrical work be completed on de-energized circuits. Energized work can only occur under special circumstances using special precautions. Power can remain on if the employer can justify work on energized components, such as when de-energizing creates additional hazards. Examples include shutting down life support equipment, emergency systems or hazardous location ventilation equipment or if power is required for start-up, diagnostics and testing procedures.
If work is near exposed live conductors or parts, NFPA 70E requires a plan for the work. Employers must have a written plan for performing the live work safely by developing an energized electrical work permit that includes:
• a description of circuit and equipment to be worked on and justification for performing work in energized conditions;
• a description of safe work practices;
• results of shock hazard and flash hazard analyses;
• shock and flash protection boundaries;
• personal protective equipment required;
• a means to restrict access to unqualified persons;
• evidence of job briefing; and work approval signatures and
Shock and flash hazard analyses. A shock hazard analysis identifies the voltage to which personnel will be exposed and boundary and PPE requirements. Table 130.2(C) in NFPA 70E can be used to determine boundary distances. The flash hazard analysis determines the flash protection boundary and PPE needed within that boundary.
The flash protection boundary is determined by methods found in 130.3(A) or Annex D of the NFPA 70E standard. Protective clothing is determined by using Tables 130.7(C)(9)(a), 130.7(C) (10) and 130.7(C)(11) in the standard.
Use of personal protective equipment (PPE). This includes flame-resistant (FR) clothing, insulated tools, face shields and flash suits. Each FR garment has an Arc Thermal Protective Value (ATPV) rating that indicates the amount of protection the clothing affords when an electrical arc comes in contact with the fabric. Refer to NFPA Table 130.7(C). (11) Protective Clothing Characteristics for guidance. u
About the author: John Boyle is corporate director of Quality, Safety and Environment at Acciona Energy North America.