Calculating j box size

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Dansos

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Hey guys I’m really struggling trying to understand 314.28 with Reference to sizing a splice box. The way I’m comprehending this is it only calculates the size of the conduits entering the box. My box is going to have 1 1/4” PVC conduit entering at top and bottom. I am calculating the 1 1/4” by 6 and getting 7.5. I’m not even sure if this is correct but if it is, this number is the MINIMUM length OR width my box can be???? I just need someone to put this into terms I can understand.
 
Dansos said:
Hey guys I’m really struggling trying to understand 314.28 with Reference to sizing a splice box. The way I’m comprehending this is it only calculates the size of the conduits entering the box. My box is going to have 1 1/4” PVC conduit entering at top and bottom. I am calculating the 1 1/4” by 6 and getting 7.5. I’m not even sure if this is correct but if it is, this number is the MINIMUM length OR width my box can be???? I just need someone to put this into terms I can understand.
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A little more info will be helpful to answer this correctly. First, is your wire size #4 or larger? Will there be any straight pulls or is everything being spliced?
If no straight pulls and all splices than multiplying the largest conduit (1 1/4") times 6 + the size of all other raceways on the same side of the box. So 7 1/2" is the minimum length of the box and as long as no conduits enter the sides, there is technically no min. width
 
There are going to be 8 #4’s in box. 4 coming in top, 4 coming in bottom and there will be 4 splices in the box.
 
There is no adding of other conduits for a straight pull and the multiplier is 8 not 6 for straight pulls.
314.28(A)(1) Straight Pulls. In straight pulls, the length of the box or conduit body shall not be less than eight times the metric designator
(trade size) of the largest raceway.
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