J Box size

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electricaldoc

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Question for everyone. This one confused my NEC instructor. It seems simple at least I thought, but found unexpected twist. You may all already know this one, but I found it contrary to all I was taught in my training.

Okay we have 6 # 10AWG THHN conductors in ? in EMT entering a J Box and exiting out opposite side(straight pull), and being used just for pull box( no devices in box) What is the minimum J Box size?

DAN
Industrial electrician
Indiana
 
Re: J Box size

Assuming that there are no grounding conductors a 4"x1.5" deep octagonal or round box would be sufficient.
 
Re: J Box size

I get the same thing. 15" sq. required, and a 1.5" deep octagonal box would have 15.5" sq.

A four-square box would also work. A single gang box would probably not work.

Steve
 
Re: J Box size

The opening question seems to suggest otherwise but would it make a difference if the wires were spliced in the j-box and does that have to be considered?

Bob
 
Re: J Box size

The opening question seems to suggest otherwise but would it make a difference if the wires were spliced in the j-box and does that have to be considered?
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Yes, it would but the original post said nothing about splices and did mention it being used as a pull box not a splice box.
 
Re: J Box size

Originally posted by electricaldoc:
Okay we have 6 # 10AWG THHN conductors in ? in EMT entering a J Box and exiting out opposite side(straight pull), and being used just for pull box( no devices in box)
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Dan I see you mentioned straight pull, I will guess that you came up with a 6" minimum box?

Straight pull or angle pull is not relevant for this box.

You only have to concern yourself with straight or angle pulls for boxes containing 4 AWG or larger.

Take a look at the last sentence of 314.16 or the first sentence of 314.28(A).
 
Re: J Box size

Since non-terminated conductors have a '1' count, and #10's are allowed 2.5 cu.in., 2.5 x 6 = 15 cu.in., where a couple of guys accidentally said sq.in. above.
 
Re: J Box size

Larry is correct it should be cubic inches. I would also add that there has been a code change in the 2005 NEC regarding looped or unbroken conductors in boxes where as they may count for more just one conductor. Take a look at 314.16(B)(1).

[ May 09, 2005, 06:11 PM: Message edited by: infinity ]
 
Re: J Box size

"I would also add that there has been a code change in the 2005 NEC regarding looped or unbroken conductors in boxes where as they may count for more just one conductor. Take a look at 314.16(B)(1)."

Getting use to the changes :D
 
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