How to connect a neutral wire to a bundle?

Question

I'd like to replace an existing light switch with a new, "smart" light switch as one of three switches in a three-gang box.

Looking in the box, I see three pairs of hot and load wires, and three ground wires, but there is also a bundle of five neutral wires pigtailed together.

I don't understand why there are so many neutral wires, or how I'm supposed to attach the neutral terminus of my switch to this bundle. Do I simply remove one of the five from the pigtail and connect it to the switches' terminus, or do I get a brand new (6th) wire, attach one end to the terminus, and pigtail the other end to the bundle?

I'm in Canada, for what it's worth.

Answer 1

Easy. You have five cables coming into the box

• supply from upstream
• onward supply to other downstream loads.
• switched load to device 1
• switched load to device 2
• switches load to device 3

Each load line has a switched hot and a neutral. I would mark the switched hots with colored tape, red, blue, yellow etc.

The switches each connect to an always-hot and a switched-hot. Sometimes installers do clever things to daisy-chain the switches, so there aren't 3 always-hots coming from the switches.

So I would expect 5 always-hots nutted together: supply, onward, and 3 switches.

And 5 neutrals nutted together: supply, onward, and 3 loads.

And of course each switch nutted to a switched-hot, if they have pigtails and are not connected directly.

Now with 3 smart switches, you'll have as many as 8 neutrals. That's too much for a wire nut, especially since smart switches tend to have pigtailed wires smaller than the other wires.

I would get a 6" length of white wire (only white or gray will do) and make a pigtail fo break up that fat wire nut, e.g. Put both supplies, the pigtail, and a couple loads under one large wire nut, then put the other end of the pigtail, remaining loads, and smart switches under another wire nut.

If the wire nuts are >10 years old, replace them. The new ones are much better.

Answer 2

You can't just take one of the neutral wires from the bundle and use it because you have no idea if it goes to the breaker box or if it goes on down the line to a light or outlet. If the 5 wires are bound together, the only thing you can do is add a sixth wire.

Note that you might need to use a larger size wire nut when adding an additional wire, and using a new wire nut is good practice anyway. The packages of wire nuts will list how many wires of a certain size they are rated to hold.