I've got a "steel city" brand ceiling box installed in a dining room for a chandelier light. I was doing the box fill calculations and came up with needing 16.0 ci. I have (3) lines of 14/2 and a luminare stud. The box came with the nm clamps factory installed. The box is listed at 15.8ci. Besides changing the box, and idea what can be done to keep it legal? Or did I mess up the box fill calculation. Why the hell would a box be rated at 15.8???
Box fill question
- Thread starter Jack Hass
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Only the clamp that is being used counts towards the box fill.
Instead of using the internal clamp use a NM connector that is on the outside of the box. That does not count towards the box fill.
Even though leaving the unused clamp/s does not count towards the box fill (unless you use one) but you can remove both clamp/s and that will give you more room.
Instead of using the internal clamp use a NM connector that is on the outside of the box. That does not count towards the box fill.
Even though leaving the unused clamp/s does not count towards the box fill (unless you use one) but you can remove both clamp/s and that will give you more room.
Don't think that helps. 314.16(B)(2) counts clamp fill, regardless of number, as one.
Interesting point. When you look at the Steel City catalog a 54151-1/2 with no clamps and the same box with clamps (AC or NM) both show as 15.8 cu in leading me to believe that they did not take the clamps into consideration in stamping the volume.
xara
Member
- Location
- minneapolis, mn
14-2 6 wires * 2 in2 =12
14-2
14-2
luminare stud vol. allowance of 1 * 2 in2 =2
14 in2 is the box fill
14-2
14-2
luminare stud vol. allowance of 1 * 2 in2 =2
14 in2 is the box fill
K8MHZ
Senior Member
- Occupation
- Electrician
If it's this one, there is are only two clamps.
http://tnb.com/ps/fulltilt/index.cgi?part=54151N
Also, if the box is 4 x 1 1/2", Table 314.16(A) says that's only 15.5 cubic inches. The box would have to be larger than 4 x 1 1/2" for removing the clamps would get 16 cubic inches.
Personally, I wouldn't sweat the 2/10 inch discrepancy. That's about the size of a sugar cube.
K8MHZ
Senior Member
- Occupation
- Electrician
Plus 2 inches for the three grounding conductors = 16 cubic (not square) inches. OP had it correct.
Edit to add:
Now I don't see a grounding conductor. If that's true, box fill is OK, but what about using a metal box on an circuit with no EGC? Also, it looks like the clamps are right on the conductors and the sheath is not sticking out 1/4 inch like it should be.
- Location
- Connecticut
- Occupation
- Engineer
314.16(B)(2) says an allowance shall be made where one or more internal cable clamps are "present" in the box, not when they are being "used" within the box.
- Location
- Connecticut
- Occupation
- Engineer
You didn't include the clamp fill. That makes it 16 ci.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
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- Sorta retired........
Does the chandalier canopy give any relief?
I personally would hang it and move on.......
I personally would hang it and move on.......
K8MHZ
Senior Member
- Occupation
- Electrician
I would say that box has to go because I don't see a grounding conductor.
314.4 says metal boxes should be grounded. Worrying about .2 of a cubic inch of fill is pretty moot in this case. Or am I just not seeing a grounding conductor????
314.4 says metal boxes should be grounded. Worrying about .2 of a cubic inch of fill is pretty moot in this case. Or am I just not seeing a grounding conductor????
mjf
Senior Member
I believe you meant sugar crystal !
Still not complete.
(3) 14/2 = 12.0 cu. in
EGC's = 2.0 cu.in.
Stud = 2.0 cu.in.
Clamps = 2.0 cu.in
TOTAL = 18 cu.in.
Zoom in. I did and I can see an EGC with each, but only about half as long as the insulated conductors.
K8MHZ
Senior Member
- Occupation
- Electrician
K8MHZ
Senior Member
- Occupation
- Electrician
Yep, now I see them. Little itty bitty ones.
K8MHZ
Senior Member
- Occupation
- Electrician
Most I have seen do, and if so, I think we are allowed to include them in our fill calculations, are we not? Otherwise, how would pancake boxes be legal?
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