110.26(A)(1) Depth of Working Space

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ed downey

ed downey

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I have a situation where there is a 480V Automatic Transfer Switch and as you would be working on the ATS behind you would be the side of a 1600A 480V Main Distribution Panel.

I am thinking that first of all this would be a Condition 2 in Table 110.26(A)(1) requiring 3.5' of clearance.

Secondly that according to the last sentence of 110.26(A)(1) that the distance of 3.5' would be measured from the front of the enclosure for the ATS and not from the circuit breaker/Bussing inside the ATS.

Let me know your thoughts on this if I am thinking of this correctly.

Thanks,
Ed
 
Re: 110.26(A)(1) Depth of Working Space

Actually this is Condition 3, which is the reason 110.26(A)(1)(c) was written.

Edit: Corrected the reference typo

[ July 20, 2005, 02:28 PM: Message edited by: rbalex ]
 
Re: 110.26(A)(1) Depth of Working Space

I didn't take that into account, because I thought that paragraph would not apply. It is limited to switchboards, panelboards, and MCCs. What we have here is a panel across from an ATS. Do you think that we have to presume that both will require maintenance at the same time, while both are energized? Would it be the same (i.e., "Condition 3") if there were two ATSs across the aisle from each other?
 
Re: 110.26(A)(1) Depth of Working Space

Bob, I fail to understand your logic if the side of the MDP doesn't have a removable panel. If it is solid, it would be a Condition 2 in my mind. :confused:
 
Re: 110.26(A)(1) Depth of Working Space

Originally posted by charlie:
Bob, I fail to understand your logic if the side of the MDP doesn't have a removable panel. If it is solid, it would be a Condition 2 in my mind. :eek: .

I agree it's a Condition 2.

With regard to Charlie B's question: "Would it be the same (i.e., "Condition 3") if there were two ATSs across the aisle from each other?" I confess I don't know. I was part of the IEEE Safety committee that submitted the 110(A)(1)(c) and we were addressing the fact that many AHJs did consider this Condition 3 for "switchboards, panelboards, and MCCs." Technically, many ATSs also meet the NEC definition of "Switchboard."
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Re: 110.26(A)(1) Depth of Working Space

I think that the wording in 110.26(A)(1)(c) makes it clear that the intent of the code is that where dead front equipment is on both sides of an aisle it is condition 3.
Don
 
Re: 110.26(A)(1) Depth of Working Space

charlie b,
I didn't take that into account, because I thought that paragraph would not apply. It is limited to switchboards, panelboards, and MCCs.
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I don't see any type of limitation in 110.26. It applies to all electrical equipment.
Don
 
Re: 110.26(A)(1) Depth of Working Space

Originally posted by don_resqcapt19: I don't see any type of limitation in 110.26. It applies to all electrical equipment.
Don
Click to expand...
I was responding to one of Bob's comments, and I wasn't clear. I meant to say that I thought 110.26(A)(1)(c) only applies to switchboards, panelboards, and MCCs, and would not apply to the configuration described in the original post.
 
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