2 AWG Box Fill

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jemsvcs

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Which article and section would cover sizing a j-box to splice 100A SEU to 2 AWG URD using split-bolts? 314.16 references 314.28. Looking at 314.28(A)(2) it seems the box would need to have a diameter six times the trade size of the largest raceway, which in this case is 1 1/4 inch sch 40 pvc (metric 35).

Any thoughts?
 
Re: 2 AWG Box Fill

you're a little bit incorrect - the '6 times trade diameter' is measured from entry to entry (i.e. your 'line' of measurement is from where the conduit enters the box from one side to where it exits on the other side)...this makes the box bigger than 6-times trade diameter.
 
Re: 2 AWG Box Fill

not following you totally....how would that make the box bigger than 6 times the trade diameter?
 
Re: 2 AWG Box Fill

sorry it is possible to make it work, but often doesn't work out that way in the field.

314.28(A)(2) is about angle pulls vs. straight thru pulls. For an 'angle' pull imagine you are entering the box on the left side and exiting the top (or bottom, rather than pulling straight across the box to the other side). The '6-times' trade size is measured from where the conduit enters the box on the left to where it exits the box on the top (or bottome....rather than measured from left-to-right).

You can see that this measurement is now a diagonal line from left-to-top.....this distance is required to be 6-times trade diameter; if your conduit isn't placed exactly right the box will quite often need to be larger than 6-times.

Let's use round numbers....a 2" conduit from left-to-top has to measure 12"....if your box was only a 12x12 you just might be able to get your conduit it place and meet the requirement....but you would have to be careful as to where you placed each piece of conduit....(very bottom left to very far top right would work....anything else would be short of the 6x requirement and you box would then have to be larger than 12")....in the field you don't often get to place your conduit in exactly the place you want it, therefore you end up using a larger box.

...hope I haven't muddled that too badly
 
Re: 2 AWG Box Fill

I see what you are saying about straight and angle pulls, but measured diagonally wouldnt the length be longer than directly across? So, take your 12 x 12 box for instance...if you had one conduit entering the top left and one exiting center right the length would be longer than 12 inches wouldn't it?
 
Re: 2 AWG Box Fill

jemsvs
You are correct with the diagonal of one pipe to one pipe. Sometimes there are multiple entries into the same box and I think that is where the other poster is going to. As far as your question, if you are using 1.25 conduit then an 8x8 box would be sufficent for code. Now in the real world and boxes bigger is sometimes better. You are using spilt bolts so you need enough room for all of the tools and your hands. You have to make the call as to how much room you are going to need. I would use a 12x12 for this project.
 
Re: 2 AWG Box Fill

Just picking nits

So, take your 12 x 12 box for instance...if you had one conduit entering the top left and one exiting center right the length would be longer than 12 inches wouldn't it?
Click to expand...
In this case you have to use 314.28(A)(1) and go 8X the conduit size.
 
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