switch loops vs. power-switch-light


Old 06-18-15, 03:16 PM
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switch loops vs. power-switch-light

I am wondering what experts do when a box is reaching full wire capacity (I dread trying to shove 14 wires into a 3-gang box), and the box has 3- and 4- way switches. Is it easier to power the lights and then feed the switches in switch loop (if that's what it's called) format?
This attached picture shows the box in question:
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The 12/2 wire on the left feeds the first of two 3-way switches - the 2nd switch in this circuit is in the garage for the front lights. The middle switch will be a 4-way switch for the garage interior lights - the other two are in the front and back of the garage. The switch on the right will be for the laundry rooms lights where the box is - and is on a different breaker. The laundry room light circuit goes power-switch-light-this switch in photo, and isn't what concerns me.

What I am thinking of doing, but don't know if it is possible, is if the garage interior lights get power first, and then from the fourth light to the first of the 3-way switches in the garage, then to this 4-way switch, then out to the other 3-way switch. 12/3 wires between switches, and 12/2 between the lights?

And then for the front lights on garage, power them first, then to the 3-way switch in the garage, then to the left-most 3-way switch here in this photo. That would allow me to remove at least the 12/2 on the left, as it will be going to the front lights.

That bottom middle 12/3 isn't fed into the box yet, as I was getting it there it started to seem like I was never going to fit all of these wires into the box. The stamping on the box reads 19/12ga, and with 3 switches I think I count 18 conductors, but that includes a huge 5-wire ground pigtail, not to mention the neutral. At what point does a professional electrician say that's too much, and go with a switch loop to get rid of at least one cable from the box?

Thank you so much if you can help.
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Old 06-18-15, 03:28 PM
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Depending on how long the wires entering the box are, you may have one cable's worth of wires long enough that the ground end will fit two green wire nuts with holes in the small ends, end to end. So you might have three or four other ground wire ends meet up with the long ground wire with the first (inner) wire nut and then two or three more ground wire ends meet up with another wire nut closer to the protruding end of the long ground wire.

There may or may not be enough additional length of the long wire protruding through the second wire nut to hitch onto one of the green switch screws. If not, add a bare pigtail under one of the wire nuts. Each switch needs a ground wire end reaching its green screw.

It is not possible for two long ground wire ends to pass through one green wire nut and out the small end to continue on to two green switch screws respectively. Even if you could make the hole in the small end of the wire nut large enough, the wires will be too chewed up by the spring inside the wire nut by the time you got everything fastened together.

For code purposes (USA) all the ground wires count as one point. Wire nuts and pigtails (short lengths wholly within the box) count zero points each.

Last edited by AllanJ; 06-18-15 at 03:44 PM.
Old 06-18-15, 03:29 PM
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3M™ Performance Plus Wire Connector O/B+BOX - Shop3M

An electrician friend of mine gave me some of the wire nuts that you see on that site. They save a lot of space inside a gang box.
Old 06-18-15, 03:48 PM
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Is it easier to power the lights and then feed the switches in switch loop
It usually use to be before 2014 NEC. 2014 NEC required a neutral at each switch box* so now you need a xx-3 cable not xx-2 cable for a switch loop. Then there is the problem of getting a neutral to the second switch box. If you come into the first switch box with power in and power out at the second box you can do it with just an xx-3 cable between the boxes.. Any other configuration will probably require xx-4 cable.

*Conduit at a switch box is an exception if the neutral can be run if needed at a later time.
Old 06-18-15, 04:38 PM
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If the lights are all on the same circuit, can't you run one switch loop with a 3 wire cable and the other two loops with two wire cable? You will be able to get rid of the power feed cable and two neutral wires.
Old 06-18-15, 06:03 PM
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Why did you use #12 wiring for lighting. I make it a rule to wire lighting circuits in #14 and alleviates the tight quarters in the switchboxes.
Old 06-19-15, 06:59 AM
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It usually use to be before 2014 NEC. 2014 NEC required a neutral at each switch box
I think it was the 2011 NEC that required the neutral at each switchbox.
Old 06-19-15, 08:35 AM
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Thanks for the correction.
Old 06-24-15, 09:09 AM
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Thanks for some tips and information. That neutral wire rule is kind of a bummer. When I started this addition, a porch entry-way was the first area to be inspected, and the electrical inspector told me I needed a 14/3 cable in this switch loop I had going on. This was probably late 2011, and I didn't question it out loud, but now I see why - the neutral wire rule was probably in effect. That really seems to get rid of 3-way switch loops, as there is one wire lacking, I think. And I've never seen ##/4 cable w/ground wire at our local home improvement stores.

Anyways, the garage circuit is 20A, and I have the lights on the same circuit as the outlets, that's why the 12ga wire. I originally wanted to run all switches in the whole addition in a power-switch-light direction, so I didn't have any white wire with black tape thing going on. I'm not an electrician, but that has always seemed iffy to me. I think in this case what I will end up doing is going with some SuperBlue boxes I found at Menards - they have a slightly larger volume, and are stamped for 23/12ga - so even if I have the laundry room light feed into this box, which would put the wires at 17, which gives me 6 'spaces' to allot for the switches, ground piggies, wire nuts, etc.

But maybe one other question, can I have two different branch circuits feed into the same box, or is that a no-no? The laundry room circuit (right-most switch in original photo) is on a different breaker. The neutrals and grounds would be kept separate of course, but the garage stuff is on one 20A GFCI and the laundry room lights and outlets will be on a 15A GFCI.
Old 06-24-15, 11:58 AM
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You can have multiple circuits in one box -- the most dramatic example of this is the main panel box which contains all of the circuits. The grounds must all connect together, but the neutrals and hots kept separate. If two circuits attach to the same device (switch, receptacle) then the two circuit breakers need to be a double pole breaker or to have a handle tie so they operate together.
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