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Breaker Panels in Offices
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Author:  jrocke@rmhfoods.com [ Thu Jan 03, 2008 3:02 pm ]
Post subject:  Breaker Panels in Offices
We have a row of 480 amp breaker panels in a plant production office that measures approximatley 10' X 15'. We are being told that we must remove the office to meet OSHA Arc Flash requirements. Does anyone have any experience with this issue?

Thanks - JR
Author:  K. Jackson [ Fri Jan 04, 2008 5:35 am ]
Post subject: 
JR-
Did you mean remove the office or remove the office door? Either one of those options does not sound right. One of the requirements is to have a flash protection boundary that can be 4 feet (it also can vary). This is the distance that people need to be standing behind in the even someone is performing live work. The person conducting the work has to wear correct PPE if they are within the boundary. Maybe there was a mis interpretation? Could you fill in a few more details for us and I am sure a few people here could give their 2 cents.
Author:  jrocke@rmhfoods.com [ Fri Jan 04, 2008 7:03 am ]
Post subject: 
Breaker Panels in Office

Thanks for the response and sorry for any confusion. We currently use a 10' x15' room where we have 4 480A Breaker Panels as a Plant Production Office with desks for about 3 people to do Production paperwork and reporting. The panels are attached to one wall in office. The panels are ALWAYS covered and we clear the room of all personnel if the panels covers need to be removed and worked in. The people sit approxiamtely 6ft. away from the closed and covered panels when they are at their desks. During a corporate Safety Audit it was stipulated that we need to "move" the office out of the room and not have any personnel working in there on a regular basis due to the risk of Arc Flash. Of course we want to protect our people and comply with the law but want to understand what the acutal reuqirements regarding this might be.

JR
Author:  Gary B [ Fri Jan 04, 2008 9:40 pm ]
Post subject: 
It would be interesting to see who is going to enforce this. One interpretation is that arc flash protective boundary is measured from EXPOSED energized conductors, though the equipment manufacturers and some folks on this forum will not state any protection achieved from covers.

We'll now have to rewire most commercial buildings with all panels in dedicated electrical rooms.....
Author:  WDeanN [ Mon Jan 07, 2008 6:51 am ]
Post subject: 
jrocke,
The boundary is not enforceable until work is being performed on the equipment, according to the NFPA 70E. The confusion should be cleared up some in the 2009 edition. I would ask them for clarification on code section for their decision.
Author:  haze10 [ Sat Jan 12, 2008 7:25 pm ]
Post subject: 
I agree with Dean. Not an issue unless covers are removed.
Author:  ARC_Dave [ Tue Jan 15, 2008 7:33 am ]
Post subject: 
Interesting...

As related to arc flash, the flash protection boundary only applies when the equipment is energized and exposed. This falls directly in line with the 70E Definition, found in Article 100, for flash protection boundary. "An approach limited at a distance from exposed live parts..." So, if its arc flash they're worried about, there's your answer.

Now on the other hand, there is a requirement in the NEC, under Article 408.38, actually an exception to the actual article that states "Panelboards other than of the dead-front, externally operable type shall be permitted where accessible only to qualified persons." That means if you have electrical panels that are not the type that have a removable cover and a separate deadfront need to be located where non-electrical folk can get to them. Those are the best I can do with that. Hope it helps.
Author:  Larry [ Wed Jan 16, 2008 4:20 pm ]
Post subject: 
Breakers In Office

The question I have for this thread is what is the consideration taken for the normal operation of these breakers? Again, not exposed to live parts, however, performing an operation of opening or closing of the breaker? And, if this is an issue, then what happens if the breaker trips while workers are at their desks?

I am sorry if I am going off topic, however, I am questioning my own interpretation the NFPA 70E as it comes to the operation of breakers and racking breakers in/out with doors or covers on. And, it comes back to NFPA 70E's interpretation of exposed live parts. Now if some are saying no protection is achieved with covers on...my interpretation is questionable. And then the next question becomes, if an incident arc energy level is stated at 18" (or whatever the case may be), is the distance measured from the first live part within the breaker enclsoure or from the outside cover?
Author:  K. Jackson [ Thu Jan 17, 2008 11:43 am ]
Post subject: 
Larry,

You hit on another one of the contradictions / confusing points in 70E. The hazard risk table says operating a CB with the covers on is category 0. Even though there are no exposed energized parts, category 0 does require safety glasses, long sleeve shirt and pants. Not sure what the writers were thinking.

Hummm??? does that mean an office worker can not flip on the breaker to turn on the lights in the morning if they are wearing a golf shirt, or they are without safety glasses or they are wearing a dress?

And they wonder why people continue to be confused by all this! :eek:
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