Box Fill

[GoldDigger]

Where does it say it must be based on a rectangle, is that part of the listing? 314.16(A)(2) requires nonmetallic boxes to be marked with their volume by the manufacturer. Does this mean the manufacturer cannot figure out the volume with those built in clamps like shown in post #11?

One other thought, boxes like the one in post #11 have no KO's which means that one of the integral clamps must be used, shouldn't the manufacturer include that in their calculation?

And if you are talking about the box as a rectangle, do you also need to deduct some fairly easy to approximate space for the two molded triangles/cylinders which provide the holes for the device mounting screws? It is not a clamp, so UL/NEC do not provide a wire equivalent for it.
Also, as mentioned earlier, the volume of the box occupied by the molded plastic clamps is very small if there is no wire pushing them into the box....

Easy experiment: tape over the clamps in the inside, fill the box with water and then see what the actual volume is.

 

[jumper]

And if you are talking about the box as a rectangle, do you also need to deduct some fairly easy to approximate space for the two molded triangles/cylinders which provide the holes for the device mounting screws? It is not a clamp, so UL/NEC do not provide a wire equivalent for it.
Also, as mentioned earlier, the volume of the box occupied by the molded plastic clamps is very small if there is no wire pushing them into the box....

Easy experiment: tape over the clamps in the inside, fill the box with water and then see what the actual volume is.

It does not matter what number you get, the number UL gets is what is going to be enforced.

 

[GoldDigger]

It does not matter what number you get, the number UL gets is what is going to be enforced.

True, I was suggesting a fun thing to for those interested in what the actual volume of the box is.

 

[Dennis Alwon]

Where does it say it must be based on a rectangle, is that part of the listing?

I wasn't stating that as a definite but I was hypothesizing.

 

[Little Bill]

And if you are talking about the box as a rectangle, do you also need to deduct some fairly easy to approximate space for the two molded triangles/cylinders which provide the holes for the device mounting screws? It is not a clamp, so UL/NEC do not provide a wire equivalent for it.
Also, as mentioned earlier, the volume of the box occupied by the molded plastic clamps is very small if there is no wire pushing them into the box....

Easy experiment: tape over the clamps in the inside, fill the box with water and then see what the actual volume is.

Then you would need to remove the tape and open up the clamps to the approximate distance they would be to hold a wire. Then refill with water to see the difference in volume when the clamps are open.:angel:

 

[handy10]

Then you would need to remove the tape and open up the clamps to the approximate distance they would be to hold a wire. Then refill with water to see the difference in volume when the clamps are open.:angel:

Since the clamps are totally inside the box/tape system in both configurations, I would expect the two volume measurements to be the same.

 

[Little Bill]

Since the clamps are totally inside the box/tape system in both configurations, I would expect the two volume measurements to be the same.

You missed my attempt at humor, hence my :angel::lol:

I was trying to say if you removed the tape and refilled with water, the water would run out before you could measure it!

 

[GoldDigger]

You missed my attempt at humor, hence my :angel::lol:

I was trying to say if you removed the tape and refilled with water, the water would run out before you could measure it!

As in the old gag from the cartoon Gordo:

"How can you tell if you are indispensable? Stick your finger in this glass of water. If it leaves a hole when you pull it out, you are indispensable."
Whereupon Gordo's buddy stuck his finger all the way through the bottom of the paper cup.​