Commercial Panelboard Clearance

[Steve Merrick]

What is the clearance requirement in front of a panelboard in a commercial office space where the panel would never be worked live? I think 3 feet is the right answer, but 110.26(A)(1) only requires 3 feet clearance in front of potentially live parts. In our facility, we would always isolate the panel at an upstream disconnect switch before removing the deadfront, so proximity to live parts is not an issue. Still, 110.26(A)(1)(a) implies clearance must be maintained in front of deadfront panels as well. What's the deal?

 

[bphgravity]

Re: Commercial Panelboard Clearance

If you can convince your AHJ that the equipment will not be worked on while energized, technically there is no working space clearance required. I doubt you will be able to positively prove this. Regardless, I don't know why anyone would install a panelboard in a location where at least 3' is not provided for the electrician to perform service to the equipment?

 

[Steve Merrick]

Re: Commercial Panelboard Clearance

Thanks for the quick reply. I have always been of the mind that 36" is required in front of a panel - period. But I am just now facing the question of space in front of panels that will never be worked live.

These panels are mounted in small mobile office trailers. The power panel locations prevent placement of more than two desks per trailer without violating the 36" rule. If we dispense with the 3-foot requirement, then the mobile office trailers can contain up to 4 desks. There is a service disconnect mounted on the outside of each trailer to isolate each trailer's service panel. Our work rules forbid live electrical work in compliance with 70E, and I can't see that we would ever authorize live work in these panels.

If 110.26 does not require 3 feet of space be maintained in front of the deadfront, I would be inclined (as the AHJ) to allow office furniture to be placed in front of these office trailers. I am aware that many of you have more experience with this than I, and I truly appreciate your help to clarify this requirement.

 

[charlie b]

Re: Commercial Panelboard Clearance

I try to defend the integrity of the working space against all intruders. In your case, you may say that live work is not allowed. But what about the next time a "production crisis" happens, and someone at the top doesn't allow you to turn off the panel because they want to keep the operation running? From the perspective of the design engineer (and that is my role in these types of projects), I never believe anyone who asserts that it will never be worked on while live.

That said, I don't know if I would call a desk "storage." The problem that the NEC is trying to prevent is an electrician not being able to move a bunch of heavy or awkward boxes or other stuff out of the way, just to gain access to the panel. We don't want that electrician to back off of the safety procedures just because it would be too much work to move the boxes. I am less inclined to worry about a desk. It is not that hard to move a desk. But if there is a desk, will there not also be a file cabinet, or perhaps a box or two of books and some other heavy, awkward boxes or other stuff?

Where do you draw the line? When is it OK, and when is it not OK, to have anything kept within the boundaries of the working space? The only safe answer is to say that it is never OK.