Wiring WTF?

[rothwem]

I went to install one of those smart switches yesterday, and when I pulled the switch plate off, I found that there was two black wires attached to the switch and the white wire and the ground in the wall were an unbroken loop that didn't connect at all to the switch. 

Should I have snipped the loop?  I'm not a pro electrician by any means, but I've swapped out a few light fixtures, sockets and switches before at my old place.  I've never seen this before though. 

[driftwood]

The switch only needs to interrupt the power the positive (black) wire. The neutral (white) can be unbroken.

The ground wire though (should be uninsulated copper), should be connected to the ground screw (green screw) on the switch to protect against shorts in the system.

If you google how to wire a light switch you'll find good photos showing how.

That being said, it sounds like your box was wired by pulling a loop of romex into the box, instead of running a line in, then a line out (hence the unbroken neutral). Normally you'd run the romex (set of black, white, and ground wire in a white sheath) from wherever in the circuit it's coming from into the box, then cut it off with about 4 inches of extra in the box for wiring. Then you'd run more romex from the light to the box, leaving the same 4" tail in the box. After that you'd connect each of the black lines to a separate screw on the switch, the white lines together, and the copper lines together and then to the ground screw on the switch.

[WranglerBowman]

Don't worry Rothwem, I was confused by this as well, but only after wiring a barn up and the breaker kept tripping every time I turned the power on.  Took me minute to go through my work and figure out not to connect the neutral to the switch.  This was my first wiring job, breakers a nice insurance policy...

[Mississippi Mudstache]

The switch only needs to interrupt the power the positive (black) wire. The neutral (white) can be unbroken.

The ground wire though (should be uninsulated copper), should be connected to the ground screw (green screw) on the switch to protect against shorts in the system.

If you google how to wire a light switch you'll find good photos showing how.

That being said, it sounds like your box was wired by pulling a loop of romex into the box, instead of running a line in, then a line out (hence the unbroken neutral). Normally you'd run the romex (set of black, white, and ground wire in a white sheath) from wherever in the circuit it's coming from into the box, then cut it off with about 4 inches of extra in the box for wiring. Then you'd run more romex from the light to the box, leaving the same 4" tail in the box. After that you'd connect each of the black lines to a separate screw on the switch, the white lines together, and the copper lines together and then to the ground screw on the switch.

+1 Good explanation. If the switch has been working properly up to now, it's wired properly. Like this:

[rothwem]

Gotcha, yeah I understand why its currently working, my issue is that the "smart" light switch needs a ground and a neutral (white wire).

I guess I could've just snipped the white wire and the ground, then hooked one end of the ground to the box and the other to the switch, but what would I have done with the second neutral?  Just wire nutted it together with the other one?

[driftwood]

Rothwem,

Yes... if you cut the neutral, you'll need and additional third piece of wire (white insulation), wire nut them all together, then take the other end of the short piece and attach that to the switch.

This video shows it pretty well. Note that the line going into the box, and the line out are connected to a pigtail that goes to the switch (for both the neutral and ground wires.

https://www.youtube.com/watch?v=anYCOmeqAeE

[rothwem]

Rothwem,

Yes... if you cut the neutral, you'll need and additional third piece of wire (white insulation), wire nut them all together, then take the other end of the short piece and attach that to the switch.

This video shows it pretty well. Note that the line going into the box, and the line out are connected to a pigtail that goes to the switch (for both the neutral and ground wires.

https://www.youtube.com/watch?v=anYCOmeqAeE

Gotcha, awesome video btw. 

I returned the switch though, maybe I'll get all revved up and do it another time.