Anything besides a neutral wire needed for "smart" light switches?
- Thread starter riverhawk
- Start date
Another question regarding wiring, I have a single gang box that doesn't seem to work with my leviton dimmer. The dimmers works everywhere else in the house except for this one. The original dimmer doesn't have a neutral connected and i'm replacing it with a zwave dimmer with a neutral. All the wiring seems correct, so it's most likely the neutral is bad somehow since it just sits inside the gang unused. How do I go about in checking the wires to see what's what? I have a multimeter but I don't know where to start to determine this. Thanks!
Are you saying that you have a white neutral wire that enters the box, but does not connect to anything else at all, not even a second white wire that exits the box and goes to the light fixture box that is being controlled?
One simple test would be to use your multimeter to measure the resistance between the neutral wire and the ground wire. Make sure the breaker for this circuit is off before you do this! The neutral and ground wire should be connected back at the service entrance. If your meter shows more than a few ohms resistance, something isn't right.
One simple test would be to use your multimeter to measure the resistance between the neutral wire and the ground wire. Make sure the breaker for this circuit is off before you do this! The neutral and ground wire should be connected back at the service entrance. If your meter shows more than a few ohms resistance, something isn't right.
RAL said:
Yeah, right now since the original dimmer didn't require a neutral, it's not connecting to anything else but in a wire nut by itself. And since the Leviton dimmers are powered by the neutral, it doesn't power up but the original dimmer is working properly which is why I suspect the dimmer.
So if something's wrong with the neutral, what do I do next?
> So if something's wrong with the neutral, what do I do next?
If the neutral is not connected, then you need to try and trace it back to where the unconnected point is. The cable in the box where the dimmer is might go directly back to your circuit breaker panel, or it might be wired through several other boxes. You can figure this out by turning off the breaker for that circuit and then testing every outlet and every light switch to see what else is on that circuit. Then start examining the wiring in each box to see if you can find one where there is another unconnected neutral.
It's possible that all the ends will be connected, which would then suggest that there is a real break in the wire hidden in the walls somewhere. That will be a lot more difficult to find.
I'm having trouble picturing how this single gang box is wired. How many romex cables are in this box, and how many conductors are in each cable? By any chance is there just one 14-3 cable with the red and black connected to the dimmer? If so, then the cable probably runs to the light fixture box, and the neutral was left unconnected there.
If the neutral is not connected, then you need to try and trace it back to where the unconnected point is. The cable in the box where the dimmer is might go directly back to your circuit breaker panel, or it might be wired through several other boxes. You can figure this out by turning off the breaker for that circuit and then testing every outlet and every light switch to see what else is on that circuit. Then start examining the wiring in each box to see if you can find one where there is another unconnected neutral.
It's possible that all the ends will be connected, which would then suggest that there is a real break in the wire hidden in the walls somewhere. That will be a lot more difficult to find.
I'm having trouble picturing how this single gang box is wired. How many romex cables are in this box, and how many conductors are in each cable? By any chance is there just one 14-3 cable with the red and black connected to the dimmer? If so, then the cable probably runs to the light fixture box, and the neutral was left unconnected there.
tmbrown97
Senior Member
I was thinking towards the latter of RAL's comments... I wouldn't go worrying about the rest of the house just yet... I'd do the resistance test that RAL mentioned between neutral and ground to see if anything is up there; I'd also turn the power back on and carefully test hot to neutral and hot to ground - you should see the 120V with both; and I'd test white to ground too just for good measure to make sure it's not showing voltage. If the neutral doesn't show continuity to ground and doesn't show voltage to hot, then yeah - the other end sounds to be disconnected. Also if it's not looping through (wires come into the box then loop back out to the fixture) then I suspect what RAL is saying - that they used 14/3 from the fixture to the switch using the red/black and they just didn't hook up the neutral. If that's the case, you should be able to open up the fixture wiring and would hopefully see the neutral just chilling in there not hooked to anything.
At least describe for us in better detail what's really going on in the switch box as far as what wires come in/out.
At least describe for us in better detail what's really going on in the switch box as far as what wires come in/out.
tmbrown97
Senior Member
Not the clearest shot in the world, but it sure looks normal. Do you have the load out and the hot in reversed by chance?
It's pretty normal in light switches for the neutrals to be tied together in the back of the box with a wire nut. It's also slightly possible you have a bad switch. In that picture though it looks like all the neutrals in the box are tied together, right?
It's pretty normal in light switches for the neutrals to be tied together in the back of the box with a wire nut. It's also slightly possible you have a bad switch. In that picture though it looks like all the neutrals in the box are tied together, right?
Work2Play said:
Yeah, the neutrals are tied together.
This was the first dimmer I worked on which is in the dining room and it didn't work, I thought it was a bad switch as well, so I tried switching out another dimmer in the family room in the same way, and I was able to get the family room dimmer switch to work by tiring the neutral from the switch to the ones like the picture
So I tried installing a new switch in the dinning room again wired the same way as the original and it doesn't work. I'll try reversing the hot and the load but would that be the issue since they seem to work correctly on the original switch?
I agree with Work2Play, this looks like pretty normal wiring.
On many dimmers, the red wire would be connected to the load (the light), and the black wire would go to the hot wire from the breaker panel. But with some dimmers, they can be wired backwards and will still work ok. So if you didn't check with a multimeter which wire is actually the hot wire from the panel, it's possible that you got it backwards if you just followed the way the old one was wired.
On many dimmers, the red wire would be connected to the load (the light), and the black wire would go to the hot wire from the breaker panel. But with some dimmers, they can be wired backwards and will still work ok. So if you didn't check with a multimeter which wire is actually the hot wire from the panel, it's possible that you got it backwards if you just followed the way the old one was wired.
This requires a bit of caution, since you will be dealing with live wires. Remember, don't touch the bare wires or the metal probe point with your bare skin with the breaker on!
First, turn the circuit breaker off and disconnect the dimmer from the two black wires. Position them so that the bare ends are not touching anything and you can probe them with the multimeter. Also position the ground wire so that it is easy to touch with the multimeter probe.
Then turn on the circuit breaker. Set the multimeter to the AC Volts scale, and touch one probe to ground and the other to one of the black wires. If you measure 120V, that is the hot wire from the circuit breaker. If you measure 0V, then that is the wire to the light. If you do measure 0V, touch the probe to the other black wire, where you should then see 120V.
First, turn the circuit breaker off and disconnect the dimmer from the two black wires. Position them so that the bare ends are not touching anything and you can probe them with the multimeter. Also position the ground wire so that it is easy to touch with the multimeter probe.
Then turn on the circuit breaker. Set the multimeter to the AC Volts scale, and touch one probe to ground and the other to one of the black wires. If you measure 120V, that is the hot wire from the circuit breaker. If you measure 0V, then that is the wire to the light. If you do measure 0V, touch the probe to the other black wire, where you should then see 120V.
