When Do I Need An Electrical Hot Work Permit?

The other day I was asked, when do you need to have an energized or electrical hot work permit?  Also, what needs to be on the energized or electrical hot work permit? 

The Standard for Electrical Safety in the Workplace provides the requirements of when an energized or electrical hot work permit is required.  An electrical hot work permit is required whenever qualified persons are working within the limited approach or the arc flash boundary, whichever is greater (Figure 1) [1].  In a 480 V system, the default limited approach boundary is 42 inches and the default arc flash boundary is 48 inches.  The arc flash boundary can be reduced by conducting an arc flash hazard analysis, but the limited approach boundary is based on system voltage (see Table 130.4(C)(a) and Table 130.4(C)(b) in NFPA 70E).

There are some cases when an electrical hot work permit is not required.  An electrical hot work permit is not required when qualified persons are conducting tasks such as testing, troubleshooting and voltage measuring [1].  Similar tasks that are not explicitly defined but inferred are conducting power quality measurements, current measurements, calibrating of systems, adjustment of components and other similar tasks where the equipment must be energized to verify proper operation.  Other tasks where an electrical hot work is not required include energizing or de-energizing equipment, or conducting visual inspections, infrared inspections and the like.  Also, any type of work on equipment where the voltage is less than 50 V does not require an electrical hot work permit, unless it is in the proximity of the limited approach or arc flash boundary of exposed live (energized) circuits or parts.

An electrical hot work permit is required for activities not mentioned above.  This includes installing new components, e.g. circuit breakers, conductors, printed wiring boards, etc. Also, an energized or electrical hot work permit is required whenever this type of work is conducted on equipment where the voltage is 50 V or greater. 

Electrical work permits can vary.  The minimum requirements are [1]:

• Description of the circuit and equipment to be worked on and location
• Justification for why the work must be performed in an energized condition
• Description of safe work practices
• Results of the shock hazard analysis including the limited approach, restricted approach, and prohibited approach boundaries
• Results of the arc flash hazard analysis including the incident energy and arc flash boundary
• Appropriate shock and arc flash hazard PPE
• Method to ensure on qualified persons are allowed in the limited approach or arc flash boundaries
• Evidence of the completion of job briefing
• Approval by management, safety officer, owner, or other company official

While utilizing PPE, energized safe work practices, or requiring energized or electrical hot work permits can help establish safe working conditions when working around or on exposed live (energized) circuits or parts, the safest method of working on electrical circuits is to de-energize these circuits or parts.

For this and other questions on electrical or product safety, please comment to this blog or send me an e-mail.

References:

1. National Fire Protection Association (NFPA).  Standard for Electrical Safety in the Workplace, NFPA 70E, 2012.  Quincy, MA USA