ARC Flash Boundary Requirements
ARC Flash Boundary Requirements
(OP)
This has been discussed in the past - but the threads are now closed.
We have many load centres (unit transformers) that have a HV switch with a dry type transformer and secondary distribution. As we are all aware the secondary transformer bus to the main breaker has a high arc flash (typically).
The end result is that the arc flash boundaries are bigger than the switchroom spacing on a lot of the installations.
My question is: "If you are just passing through the room do you need to suit up in the required PPE, or just when "disturbing" the system?"
The reason I am asking is that the transformer ventilation makes the transformer "open" to the environment, and the passer by....
Thanks TULUM.
We have many load centres (unit transformers) that have a HV switch with a dry type transformer and secondary distribution. As we are all aware the secondary transformer bus to the main breaker has a high arc flash (typically).
The end result is that the arc flash boundaries are bigger than the switchroom spacing on a lot of the installations.
My question is: "If you are just passing through the room do you need to suit up in the required PPE, or just when "disturbing" the system?"
The reason I am asking is that the transformer ventilation makes the transformer "open" to the environment, and the passer by....
Thanks TULUM.






RE: ARC Flash Boundary Requirements
Wear atleast a cat.2 PPE when not intending to interact.
RE: ARC Flash Boundary Requirements
If the Arc Flash rules have to be applied retroactively to existing older installations, that would be nearly impossible.
How would the operating staff have to Suit Up just to reset a relay or take a meter reading? That would be a walk-through situation I imagine.
Comments?
rasevskii
RE: ARC Flash Boundary Requirements
Rafiq Bulsara
http://www.srengineersct.com
RE: ARC Flash Boundary Requirements
David Castor
www.cvoes.com
RE: ARC Flash Boundary Requirements
RE: ARC Flash Boundary Requirements
The reason I asked is that it seems that
(a) because the definition for the flash protection boundary itself does not directly mention that you must interact with the system for the PPE to be required (in the standards but not in the definition), most people are under the assumption that as soon as you step into the boundary you require PPE regardless of interaction....
(b) With the louvers on the dry type enclosure, the bus would be considered "energized and not enclosed"?
RE: ARC Flash Boundary Requirements
The boundary applies when work is being performed. PPE is required when within the boundary and when there is an arc flash hazard. FPN No. 1 of the definition of arc flash hazard in Article 100 states
Walking through the area is not working or interacting with the equipment.
RE: ARC Flash Boundary Requirements
RE: ARC Flash Boundary Requirements
h
In this case if anyone had been in this compartment then I don't think PPE would have helped!
Thanks
RE: ARC Flash Boundary Requirements
It comes down to practicality, company policies and insurance requirements. No code or standard can cover every situation. A little reasonable judgement needs to be applied. It may not make sense to require PPE just walking past a passive panel or switchboard. I would be less comfortable if there were active controls regularly operating circuit breakers, and less comfortable still if breakers or switches were being operated manually.
The national codes in the U.S. do not require PPE. Work practices are not within the scope of the NEC. NFPA 70E is not a code suitable for adoption by building authorities, but rather a standard practice. OSHA recognizes NFPA 70E as a standard for safe work practice, but does not directly enforce it.
Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.
RE: ARC Flash Boundary Requirements
RE: ARC Flash Boundary Requirements
RE: ARC Flash Boundary Requirements
I agree. NFPA helps you understand the hazards but it can't cover every possibility. In the end, it's up to the employers and employees to assess the risks and decide how to handle safety at their facility. I doubt OSHA will accept "we followed the standard" as an excuse if someone gets hurt.