NEC Box Fill Exercise Real World

[jar546]

all wires are number 12 AWG and the 1900 box is 2 1/8 inches deep. is there adequate space inside this junction box for the number of wires present? Also, what happens if they decide to use this as the receptacle under the sink for the dishwasher and garbage disposal?

 

[bill1952]

Deep plaster ring.

I've wired a couple of one family dwellings and I just print out a spreadsheet of all that size stuff and keep it in my toolbox. Easy and safe.

 

[ICE]

Have a rubber mallet.. a leather one too.
To be honest, I never count the number of wires and then do calculations. If it looks like I need the mallet, it is too full. If it's just a pain in the ass getting it all in... maybe it's okay. It's mostly in that gray area that doesn't exist in the NEC.

 

[wwhitney]

Kind of hard to count from the pictures, but I see 10 conductors coming in on the flex, and (3) 12/2 NM cables. If just a junction box, that would make 17 allowances required (16 circuit conductors, plus 1 allowance for 1 to 4 EGCs, and 0 internal clamps), at 2.25 in^3 per allowance, for a required volume of 38.25 in^3. Table 314.16(A) tells us a 4 x 2-1/8 box is 30.3 in^3. So a mud ring (or box extension) with a volume of at least 8 in^3 is required.

If devices are added to the box, they get 2 allowances each, or 4.5 in^3. So increase the minimum volume of the mud ring accordingly.

If I miscounted the wires, adjust the computations for the correct count accordingly.

Cheers, Wayne

 

[jar546]

Kind of hard to count from the pictures,

I was hoping the two angles would make it easier. The electrician will probably not be happy that I pulled all of the wires out. More than likely that will get a duplex receptacle so it will be over unless an extension ring is added.