I understand that when a breaker, switch, MCC section ect. has had an Arc Flash Survey, that if it is then labeled "dangerous" that this means you are never to get in it energized. That you aren't even able to open the doors on the equipment because no amount of PPE can protect you from the blast. With that being said my question is if on an MCC section (480 volt) with the breaker door closed on one of these labeled "Dangerous", if an arc fault explosion happened while energizing the breaker would the closed breaker door protect an individual? I've seen doors blown off from these explosions. We have this situation and the instructions are for only electrical personnel to close in the breakers with PPE on. My concern is that if the blast can kill me I don't want to do it! I understand that a barrier helps with the arc flash but what about the blast energy?
Arc Fault Label Dangerous
- Thread starter tpd
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- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
A breaker enclosure door can only be considered to protect from arc flash (including blast energy) if it has been specifically listed as doing that. If it is not so rated, yes the door hitting you in the chest or head can do damage that the PPE is not designed to protect you against. A standard safety instruction is not to stand directly in front of the door or panel of the equipment you are interacting with. Stand to the side instead, if you have to be touching it.
Opening the door, by itself, may be a dangerous level of interaction, but things that can be done with the door closed (like energizing the breaker) can certainly lead to an arc flash too and must be done cold or else remotely. The Dangerous level, as you noted, means that the amount of energy which might be released is beyond the ability of PPE to protect against adequately.
Evidently the design of these make it hard to close them in so I don't believe standing to the side will work on the ones head high and above. This is the first survey in this part of the facility and the first time I've seen the actual MCC section rated dangerous. Up until now the only dangerous findings have been large feeders for the MCC's as the protection to the feeders through transformers needs upgraded. But the feeders themselves allowed adequate protection for the MCC's. So now we have the issue of safety from the blast perspective and not just the arc flash. This place tells everyone to not touch the breakers and call an electrician without any regard to the safety for electricians as if we are somehow immune to the danger! Thank you for input.
zog
Senior Member
- Location
- Charlotte, NC
You have 2 choices, mitigate the hazard level or use remote operators.
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