Pull Box vs. Auxiliary Gutter

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bparisi

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I have an automatic transfer switch which I need to enter with 4 - 31/2" conduits. I enter the room from a side wall .I have only 18" to the ceiling - not enough radius to bend the conduits down into the switch. I plan to put a pull box on top of the switch up to the ceiling and enter the box from the back. If I nipple the 4- 31/2" conduits into the switch is the box a pull box which would ned to be sized in accordance with 314.28, or is it an auxiliary gutter.

My contention is that if the bottom of the box does not open into the top of the ATS, it's a pull box and if the bottom of the box and top of ATS enclosure are open, it's an auxiliary gutter.

Any opinions?
 
I am trying to picture this. If I read correctly you propose on extending the top of the ATS with an open bottom gutter? I see 366.58 and 366.100 and 6 times the pipe diameter plus 314.28(2)
 
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Pull Box vs. Auxiliary Gutter

Exactly. My contention is that if the bottom of the box is closed and the top of the ATS is closed and I connect them with nipples, then it's no longer an auxiliary gutter, but a pull box, which must conform to article 314.
 
By definition I think it is a pull box. The intended use of the equipment is the determining factor. Because it is not being used to supplement the wiring space of the ATS it is not an auxiliary gutter.

I see your point though, Article 366 really needs improvement. For example, 366.58(B) contradicts the very definition of an auxiliary gutter. Based on the definition it is impossible to use a gutter as a pull box. At the very least a gutter used as a pull box would be a wireway.
 
Conduit entering from back of a pull box and leaves from bottom wall,if this is your case,your pull box shall be sized 4-1/2" conduit x 6= 27".
but depth shall be sized based on table 312-6a(min. wire bending space).
Pull box shall have front removable cover.
 
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