?
Wednesday, May 27, 2015
Question:
Re: CQD answer published Monday, May 18, 2015 - Ceiling Pancake Box
Charlie, I wonder if you could relate to us your understanding on using a 3” pancake boxes for use with NM cable. The box has a capacity of 4 cu. and if I use a single NM cable containing two conductors plus an equipment grounding conductor I have exceeded the box fill capacity. Contractors are telling me they are using the canopy to add fill capacity and I tell them the canopy needs to be identified for this use. The only way it might be acceptable would be if the installer were using conduit, AC cable or EMT thus eliminating the need for an equipment grounding wire. Thanks in advance. See Ya in Jackson Hole.
George H. Little
Re your answer to the question about independently supporting ceiling fans: you are correct that the NEC allows the fan to be supported independently from the box, however this support is only acceptable if approved. In our area the AHJ will not approve anything other than a listed ceiling fan box as it relieves him of the responsibility for determining if your independent means of support is adequate. We need to keep in mind that even if the code allows something, it is still subject to approval by the AHJ. Keep up the good work, we all appreciate it.
Donald Haskin
Regarding the pancake ceiling boxes:
One has to be careful that they are using a box rated with the proper wire fill. If the box is stamped 6.0 cu in that is nice, but you have to make sure that the connectors are external clamps. The standard "buttons" that some manufacturers use, e.g., Arlington, are not suitable as they are counted as internal clips. Raco makes a connector that they supply with their box that is listed as an external clip. This should be a consideration whenever using a pancake box.
All the best. Jeff Glanstein,
A
Answer:
Hey Guys thanks for your comments. Yes, the box would need to be of sufficient size to comply with 314.16 but a 6.0 cubic inch pancake box is available and would be for 14 AWG conductors if an external cable connector is used. A domed cover that is marked with its volume could also be used to add to the volume as stated in 314.16(A). And yes the AHJ does have the responsibility of determining if an independent mans of support as stated in 422.18 is adequate as and could choose not to accept something by using 90.4.