When applying the safety-driven requirements in NFPA 70E, many users question why there is not more prescriptive direction for every task they perform, and they often want a method of procedure that gives step-by-step instructions. It is just not possible for that to be codified, because each workplace, task and potential exposure must be evaluated on a case-by-case basis.
Questions always arise with respect to operating equipment in a “normal operating condition.” Likelihood and potential severity must be considered in all risk assessments for normal operation. See Exception No. 1 following 110.2(B). A normal operating condition exists where the equipment is properly installed and maintained; rated for the available fault current; used in accordance with instructions included in the listing and labeling, and in accordance with manufacturer’s instructions, and where all doors are closed and secured, all covers are in place and secured and there is no evidence of impending failure.
No easy button exists
It is prudent for the standard to recognize electrical equipment in a normal operating condition. See the last sentence in Informational Note No. 1 following the definition of arc flash hazard: an arc flash incident is not likely to occur under normal operating conditions when enclosed energized equipment has been properly installed and maintained. The likelihood of an incident is not the only thing worth consideration. The standard user must always consider the potential severity, and no easy button exists.
For example, say a 2-pole, 120/240V, 100A circuit breaker in a dwelling unit is found to be in normal operating condition and has a low likelihood of arc flash exposure and low potential severity. In this case, an employer can make a determination that normal operation of this device can be done safely without PPE. However, consider a 2,000A frame low-voltage power circuit breaker (LVPCB), found to be in normal operating condition used as a service disconnect at 480/277V.
While the likelihood of occurrence is low, the potential severity is very high. The employer’s risk assessment should make the determination that additional protective methods are required and refer to the hierarchy of risk control. All of the risk reduction methods should be considered. Engineering controls would work best through using a device that allows for remotely operating the LVPCB. That removes the employee from the area in front of the device in the event of a failure. PPE is always the last option.
Likelihood of arc flash
Using Table 130.5(C) to determine the likelihood of an arc flash also results in questions. For example, in 2024, a new task was added to address “Operation of a CB or switch the first time after installation or completion of maintenance in the equipment.”
This task applies to any operating condition and is listed as having a likelihood of occurrence of an arc flash incident. Employers should develop policies and procedures to address necessary protective measures when energizing new distribution systems. This will require an arc flash risk assessment in accordance with Section 130.5.
For example, consider closing two molded-case circuit breakers for the first time, in two different exposures. First, consider a 400A molded-case circuit breaker with an interrupting rating of 65 kA in the basement of an apartment building, in a switchboard immediately downstream of a 2,000-kVA transformer secondary at 480/277V. The available fault current at the transformer secondary (assuming an infinite primary) is likely over 40,000A. The potential severity is high and the arc flash risk assessment must identify additional protective measures adequate for the potential exposure.
Second, consider closing 15A and 20A circuit breakers on the sixth floor of the same building in a panelboard located in an apartment and protected by a 100A, 2-pole molded-case circuit breaker at 120/208V. Here, the risk assessment could determine that leather gloves, hearing protection and safety glasses are all that is needed.
The user must make these determinations; the standard will not do it for them. The goal is always to provide a practical safe working area for employees relative to the hazards arising from the use of electricity, which is NFPA 70E’s stated purpose. Our goal is to prevent injury, and we want everyone going home in the same condition they came to work. We owe that to our employees and their families.
Header image: Getty images / Golden Sikorka
About The Author
DOLLARD is retired safety coordinator for IBEW Local 98 in Philadelphia. He is a past member of the NEC Correlating Committee, CMP-10, CMP-13, CMP-15, NFPA 90A/B and NFPA 855. Jim continues to serve on NFPA 70E and as a UL Electrical Council member. Reach him at [email protected].