Help with box fill calculation
#1
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Help with box fill calculation
I was wondering if someone could help me with a box fill calculation. I have a 1-gang NM box (Carlon 18 cu. in.). There are 4 - 12 gauge cables that terminate in it. There is also a 3-way switch. I am concerned that it is overfilled. From my calculation, it appears that there should be at least a 22.5 cu. in. box. Is that correct? Do they even make a 1-gang box that large? I appreciate any input.
#2
You have:
8 conductors entering and exiting (maybe more if any of those cables are 12-3)
1 conductor to represent all grounds
2 conductors to represent the device (switch)
-------
11 conductors * 2.25 cu/in for #12 wire = 24.75 cu in minimum box size
There may be some speciality boxes out there greater than 22.5, but that is the largest "deep" single gang box commonly available. I'd say you need a 2 gang box in that spot.
8 conductors entering and exiting (maybe more if any of those cables are 12-3)
1 conductor to represent all grounds
2 conductors to represent the device (switch)
-------
11 conductors * 2.25 cu/in for #12 wire = 24.75 cu in minimum box size
There may be some speciality boxes out there greater than 22.5, but that is the largest "deep" single gang box commonly available. I'd say you need a 2 gang box in that spot.
#3
If it is a new installation they make a two gang box where half is covered by the Sheetrock.
Edit: More research thanks to PCBoss shows the box I was refering to is only 17 cubic inches so... never mind.
Edit: More research thanks to PCBoss shows the box I was refering to is only 17 cubic inches so... never mind.
Last edited by ray2047; 10-23-15 at 09:07 PM. Reason: Removed possibly incorrect information.