Have I Run Too Many Lines In This Box?

Question

In an effort to run the shortest amount of cable, I'm afraid I might have inadvertently run too many cables to the same 3-gang, 44 cubic inch box.

A Brief Overview

44 cu inch box
14/2 wire all around with a total of six lines running into this box
1 x Source Line
2 x Branches to feed other light circuits
3 x Lines to switches at this box (overhead light, mirror sconce, exhaust fan)

At its start, it didn't feel wrong, but now I'm faced with bonding six grounds and their corresponding pigtails, three hot wires with their associated pigtails, and finally, three neutrals, along with their associated pigtails, for a total of 15 (I think) individual wires in a single box.

Is this too much? Can I make this work, while keeping everything safe and to code? Before posting, I read a similar post about various ways to handle larger groups of related wires. Perhaps one of these approaches will work for me, but I don't want to go down that rabbit hole if this is just wrong.

Important Note: The vast majority of the lights are recessed LEDs at 12 watts each, so I'm nowhere near the current capacity of this 15 amp circuit.

How big is the box? Box fill calculations seem to indicate you need a 45 cu in box. — A. I. Breveleri, Jan 22 '22 at 00:28
Yes, what size is the box? (It should be stamped into the box itself) — ThreePhaseEel, Jan 22 '22 at 00:31
@ThreePhaseEel I just updated the post to specify the box size of 44 cubic inches. I'm guessing that's a firm limit, too. No wiggle room for another inch? — senfo, Jan 22 '22 at 01:41
Wait - what gauge wire? I calculated for 12/2. If that's 14/2 then you only need 40 cu in. — A. I. Breveleri, Jan 22 '22 at 02:03
I made another error - I assumed internal clamps. But with that box you have none. That yields 42.75 cu in for 12 gauge wire or 38 cu in for 14 gauge. — A. I. Breveleri, Jan 22 '22 at 02:28

score 7 · Accepted Answer · answered Jan 22 '22 at 02:55

You have 12 power (phase or neutral) conductors, no internal clamps, 8 equipment grounding conductors, no studs or hickeys, and 3 yoke devices. All your wires are 14 gauge.

NEC 2017, Article 314.16 defines volume allowance (VA) requirements:

One for each power conductor that terminates within the box. 
One for all internal clamps together. 
One for all equipment grounding conductors together. 
One for each luminaire stud or hickey. 
Two for each yoke device (outlet or switch).

Your VA:

12  12 power conductors 
 1  8 equipment grounding conductors 
 6  3 yoke devices 
-- 
19

NEC 2017 defines the space requirement for 14 gauge wire as 2 cubic inches per VA, or 38 cubic inches total. Your box is 44 cubic inches, so you're all right.

I had a difficult time deciding which of the two answers I thought was best because they're both really good and helped me out, but this one just broke it down a little better for me to understand it. Many thanks for your input on this. — senfo, Jan 22 '22 at 15:32
So it could actually fit one last 3-wire cable? a B\R\W(G). Or just shy of two more, 2-wire. — Mazura, Jan 22 '22 at 20:06

score 6 · Answer 2 · answered Jan 22 '22 at 02:32

I'm counting six /2 cables, so the 2 wires in each give us 12 "wire counts".

All grounds together = 1 wire count. Under NEC 2020 grounds are "4 for the price of 1" so 2 counts. That'll be important later.

I see 3 gangs, so up to 3 yokes. 2 wire counts per yoke, so 6 counts.

Total 19 (20 if NEC 2020).

All #14 so multiply by 2.00 cubic inches = 38 or 40 cubic inches.

If this was #12 you'd multiply by 2.25 cubic inches = 42.75 or 45 ci.

Have I Run Too Many Lines In This Box?

2 Answers2