Pull point for 480V parallel feeders NEC 314.28

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Isaiah

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Electrical Inspector
I’m reviewing a large pull box Construction wants to install. The proposed box is 30”W x 36”H x 12”D. There are two feeders involved: both are 600kCMIL; 3 per ph with a full sized neutral and #1/0EGC. The conduits are 3.5” each, RGS - 6 total.
The conduits will penetrate a wall and enter the back of the Box, then exit the left side (looking at the front) The box appears long & wide enough to meet 314.28, but I’m a little concerned about the depth. It has a hinged door opposite the wall penetrations which seems to make this box acceptable as far as intent. Cable is single conductor, 600V insulation, XHHW-2 approximately 1 inch OD which according to 336.24 makes the bend radius around 5 inches. Any comments?


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based on NEC 2017

for pull boxes with cables #4 awg and larger, the conduit arrangement and sizes will determine the minimum dimensions. You reference 6 conduits but not a layout (2 high x 3 wide? 3 high x 2 wide?). the layout will determine the minimum box size with conductor size only entering the picture if you use the exception.

reference 314.28
what you are doing is a angle or U-pull. 314.28(A)(2) requires the distance from conduit entry to opposite wall be 6x the trade size of largest conduit, plus the sum of the remaining conduits in that row. The exception is if the opposite wall is removable, you can reduce depth to 1 wire per termination table 312.6(A).

if your arrangement is 2 high, 3 wide, you need a minimum pull box WIDTH of 3.5 x 6 + 3.5 + 3.5, or 28 inches
for 3 high, 2 wide, you need a minimum pull box WIDTH of 3.5 x 6 + 3.5, or 24.5 inches.

regarding the depth, your enclosure front is removable so the exception can be used. Table 312.6(A) requires 14 inches.

i suggest being careful of the distance between raceway entries enclosing the same conductor must be 6 x the trade designator of the larger of the two conduits, or 21 inches for 3.5-inch conduits. That leaves a bit more than 9 inches on the right side to work with (depends on how far from the rear you terminate the left side conduits, if you want to test your trigonometry skills). I would install such that if an inspector, if so inclined, measured from the inner edge of one conduit to the inner edge of the other, not center to center.

finally, it looks like the codebook allows you to use the minimum permissible conduit size for the conductors being pulled, and not the size of the conduit actually installed. you might save a couple of inches doing it that way, not worth the effort until there is good reason, imo.
 
drktmplr12 said:
based on NEC 2017

for pull boxes with cables #4 awg and larger, the conduit arrangement and sizes will determine the minimum dimensions. You reference 6 conduits but not a layout (2 high x 3 wide? 3 high x 2 wide?). the layout will determine the minimum box size with conductor size only entering the picture if you use the exception.

reference 314.28
what you are doing is a angle or U-pull. 314.28(A)(2) requires the distance from conduit entry to opposite wall be 6x the trade size of largest conduit, plus the sum of the remaining conduits in that row. The exception is if the opposite wall is removable, you can reduce depth to 1 wire per termination table 312.6(A).

if your arrangement is 2 high, 3 wide, you need a minimum pull box WIDTH of 3.5 x 6 + 3.5 + 3.5, or 28 inches
for 3 high, 2 wide, you need a minimum pull box WIDTH of 3.5 x 6 + 3.5, or 24.5 inches.

regarding the depth, your enclosure front is removable so the exception can be used. Table 312.6(A) requires 14 inches.

i suggest being careful of the distance between raceway entries enclosing the same conductor must be 6 x the trade designator of the larger of the two conduits, or 21 inches for 3.5-inch conduits. That leaves a bit more than 9 inches on the right side to work with (depends on how far from the rear you terminate the left side conduits, if you want to test your trigonometry skills). I would install such that if an inspector, if so inclined, measured from the inner edge of one conduit to the inner edge of the other, not center to center.

finally, it looks like the codebook allows you to use the minimum permissible conduit size for the conductors being pulled, and not the size of the conduit actually installed. you might save a couple of inches doing it that way, not worth the effort until there is good reason, imo.
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I really appreciate the response!


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