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