- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
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.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?
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.