Box fill question

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Jack Hass

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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???
 
Listing question on marked box volume....

314.16(A) says the marked volume is the total volume of the assembled sections. Wouldn't that account for clamp fill already?
 
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.
 
Power comes into the light, switch leg, and sending power to another light. Seems ridiculous that this is even an issue. The luminare stud was removed for the picture.
 

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Smart $ said:
To get 16ci fill, your box appears to have 4 clamps. Remove one.
Click to expand...

Don't think that helps. 314.16(B)(2) counts clamp fill, regardless of number, as one.

Smart $ said:
Listing question on marked box volume....

314.16(A) says the marked volume is the total volume of the assembled sections. Wouldn't that account for clamp fill already?
Click to expand...

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.
 
Smart $ said:
To get 16ci fill, your box appears to have 4 clamps. Remove one.
Click to expand...

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.
 
xara said:
14-2 6 wires * 2= 12
14-2
14-2

luminare stud vol. al. 1 * 2=2

14 in2 is the box fill
Click to expand...

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.
 
edward said:
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.
Click to expand...

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.
 
Does the chandalier canopy give any relief?
I personally would hang it and move on.......
 
K8MHZ said:
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.
Click to expand...

I believe you meant sugar crystal !
 
xara said:
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
Click to expand...

K8MHZ said:
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.
Click to expand...

david luchini said:
You didn't include the clamp fill. That makes it 16 ci.
Click to expand...
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.
 
K8MHZ said:
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????
Click to expand...
Zoom in. I did and I can see an EGC with each, but only about half as long as the insulated conductors.
 
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