Box volume calculation

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hhsting

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Please see attached sketch. I plans that have pull box that requires volume fill calcs. The pull box has 15 circuits and 4 equipment grounding conductors all #10 enter and leave.

Each circuit is either 120V 1p or 208V 1p. Based on NEC 2014 Section 314.16(B):

Since I have 15 circuits, 2 conductors each thats 30 conductors. Since I have 30 enter and leave thats 30x2=60 conductors total.

The equipment grounding conductor is counted once thus total conductors are 60+1=61.

Based on Table 314.16(B): each #10 is 2.5 in cube.

Thus total volume is 61x2.5=172.5 inch cube.

Would the volume then need to be at least 172.5 in cube correct or incorrect?

b8f5eac2999ba00085544e46101d0bef.jpg
 
How many conduits and what size conduits?
That might be more of a deciding factor for the pull box size than conductor volume calc.
 
sw_ross said:
How many conduits and what size conduits?
That might be more of a deciding factor for the pull box size than conductor volume calc.
Click to expand...

There are no conduits. The pull box is fed from 2 inch by 2 inch wireway cross sectional area 4 sq inch contain 15 ckts and 4 egc

Conductors leaving pull box are in Legrand AL200 channel cross sectional area 4.8 sq inch
 
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More than just the ci needs to be considered also like @sw_ross stated the number and size of conduits, maximum bend radius, placement of conduit in relationship to each other all need to factor in.
 
1. If the conductors only pass thru the pull box without a splice loop they only count as 1
2. If any of the equipment grounds are isolated grounds then you needed an added conductor
 
If the conductors are not spliced and they pass thru only count as 1.
 
Fred B said:
More than just the ci needs to be considered also like @sw_ross stated the number and size of conduits, maximum bend radius, placement of conduit in relationship to each other all need to factor in.
Click to expand...

Where is max bend radius, placement of conduit. I dont see it in NEC 2014 section 314.15(B)?
 
Isnt conduit size irrelevant for small conductors? Thought conduits only matter when using #4 and larger wires. Otherwise you use cubic inch volume.
 
Fred B said:
More than just the ci needs to be considered also like @sw_ross stated the number and size of conduits, maximum bend radius, placement of conduit in relationship to each other all need to factor in.
Click to expand...
As I understand the OP all conductors are smaller than #4 so no of this applies. It's just a simple box fill question.
 
Fred B said:
More than just the ci needs to be considered also like @sw_ross stated the number and size of conduits, maximum bend radius, placement of conduit in relationship to each other all need to factor in.
Click to expand...
There is no bend radius rules in the NEC for conductors rated 1000 volts and less.
 
So back to the beginning, i think hhstings calculation is correct if the wires are spliced. If it is just a pull box then it can be about half that size.
 
hhsting said:
There are no conduits. The pull box is fed from 2 inch by 2 inch wireway cross sectional area 4 sq inch contain 15 ckts and 4 egc

Conductors leaving pull box are in Legrand AL200 channel cross sectional area 4.8 sq inch
Click to expand...
suemarkp said:
Isnt conduit size irrelevant for small conductors? Thought conduits only matter when using #4 and larger wires. Otherwise you use cubic inch volume.
Click to expand...
Correct. Now it appears from his drawing there is 15 outgoing raceways, cables, or whatever ( Legrand AL200 is maybe surface metal raceway?) leaving this pull box. Seems to be able to physically leave with that many of whatever it is will likely mean a pretty decent sized enclosure will be used and likely will have more cubic inch capacity than the conductors will require, but doesn't hurt to double check. Bet each entry needs as much enclosure wall area as a typical 1/2 or 3/4 conuit would need as a bare minimum, this probably isn't going to be a 4x4 box or even a 8x8 box in too many cases. Even if it were an 8x8x4 that would be sufficient for about 102 10 AWG conductors (and any/all EGC's that terminate in the box only count as one)
 
Yep, find a box big enough to terminate 15 - 3/4” conduits and that will probably definitely be big enough for cubic inches #10s will require. Problem solved.
 
Greentagger said:
Yep, find a box big enough to terminate 15 - 3/4” conduits and that will probably definitely be big enough for cubic inches #10s will require. Problem solved.
Click to expand...
Well maybe big enough when you only using say two sides for entries. You can get 4-11/16 square boxes with 3 KO's each side and five in the back which would be 17 entries but that probably not going to work to crowd them all into that small of a box. Even if it can be done good luck pulling and managing it.
 
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