[WEAREMARSHALL]

Pulled cover off a couple of light switches during re-model. Have 2 regular 12-2 w ground wires, one power supply, one to light. All black wires nutted together and both white wires hooked to switch. Using meter when switch is off shows 140 volts. Light works fine and so does switch. Any ideas? Never seen this before. Thanks.

 

[jmon]

Welcome to the forum wearemarshall.

I have seen funky readings before using a multi-meter. It's possible you could be reading some phantom voltage or it could be the meter you are using. In a standard US residency it should read closer to 120v not 140v.

Verify your meters accuracy by checking another outlet, or try a different meter with a good battery and see if you get the same results. Just a suggestion.

An electrician will be along soon with a better explanation.

 

[WEAREMARSHALL]

During re-model I pulled cover off a light switch. Box has 2 12/2 w/ground wires coming in back, one wire to switch,one to light. All black wires are nutted together. Both white wires are hooked to switch. Light and switch work fine but with switch and light off I'm reading 140 volts. No volts when switch is on. Any ideas?? never seen this before. Would like to add another switch and light but kind of weary now.

 

[jmon]

Welcome to the forum wearemarshall.

I have seen funky readings before using a multi-meter. It's possible you could be reading some phantom voltage or it could be the meter you are using. In a standard US residency it should read closer to 120v not 140v.

Verify your meters accuracy by checking another outlet, or try a different meter with a good battery and see if you get the same results. Just a suggestion.

An electrician will be along soon for a better explanation.

 

[joed]

140 volts where? between the whites? useless reading. Means nothing.

The blacks should be on the switch?

 

[joed]

No need to double post.
Same answer I gave in other post.

140 volts where? between the whites? useless reading. Means nothing.

The blacks should be on the switch?

 

[oh'mike]

Welcome, two threads merged------please , no need to start two threads on the same subject.

 

[WEAREMARSHALL]

Sorry 120v at switch but only when switch is off. When switch and light are there is no juice on either terminal. Why is the white hot? Shouldn't black be hot? Be bad to just reverse colors or not?

 

[WEAREMARSHALL]

Welcome, two threads merged------please , no need to start two threads on the same subject.

Ya SORRY !!!!! No need for so many different confusing sub-forums. Won't happen again!

 

[jbfan]

Sorry 120v at switch but only when switch is off. When switch and light are there is no juice on either terminal. Why is the white hot? Shouldn't black be hot? Be bad to just reverse colors or not?

You need to take the light down and see what colors are connected to what.
Where does the power come from?
You need to back track to see what wires are connected to what and try to make this right.

Who did the wiring?

 

[PandJ]

guessing wired in reverse. Is this a 3 way switch? Maybe someone got confused before and ended up with that wiring setup.

 

[joed]

Power is on the white when switch is off because it is feeding from the hot through the light and back to the switch on the white wire. As long as the switch is open white from the has potential of 120 volts. No current flow so no voltage drop across the light. Connect the white to the other white current flows and the voltage drops across the light.

The two whites should be tied together in the switch box and the two black should be on the switch. The way it is now there is always power on the light.

 

[WEAREMARSHALL]

Power is on the white when switch is off because it is feeding from the hot through the light and back to the switch on the white wire. As long as the switch is open white from the has potential of 120 volts. No current flow so no voltage drop across the light. Connect the white to the other white current flows and the voltage drops across the light.

The two whites should be tied together in the switch box and the two black should be on the switch. The way it is now there is always power on the light.

Thanks, it just makes me weary about switching cause like I said the light and switch work perfectly, no issues I've just never seen a single pole switch wired with both black wires nutted up and both white wires wired to switch. Also with my general knowledge of wiring I've never seen no voltage on a switch with it on but as soon as you turn the switch off you instantly get 120 volts. I appreciate everyone's help.

 

[FrodoOne]

Thanks, it just makes me weary about switching cause like I said the light and switch work perfectly, no issues I've just never seen a single pole switch wired with both black wires nutted up and both white wires wired to switch. Also with my general knowledge of wiring I've never seen no voltage on a switch with it on but as soon as you turn the switch off you instantly get 120 volts. I appreciate everyone's help.

From your statements it appears that you are reading 120 V (140 V [?]) across the switch connections/contacts when it is turned off - which is normal, except that you should not read much more than 120V so check your meter, as suggested by jmon.

While I am surprised that no one has yet suggested it, (with the switch turned on) you should take a reading between the switch connections and the "Earth" at the switch/box - assuming that there is one. If you read 120 V (or there abouts), it means that the white wire is connected to the "Line" (Hot) side of the supply and, hence, the Black is (presumably) connected to the "Neutral" - which is incorrect.

If you read zero (or there abouts) it means that the light is being switched via the "Neutral" - which is also incorrect.
(In the latter case, you should expect to read 120 V between the Black wires [after you switch off the breaker, remove the wire-nut and switch on the breaker] and the Earth.)

 

[danpik]

The rerason you are getting a voltage reading across the two terminals is simple. When the switch is off, there is no electricity flowing past the "hot" side of the switch. when you connect your meter between the hot terminal and the load terminal you are effectively creating a path for the electricity to flow. This is the same as turning the switch on. BTW, this is a good way to ruin some cheaper meters as they can not limit the current flow. Anyway, when you turn the switch on the power on both terminals is the same and can not be measured as there is no zero reference source. An easy way to see this is to take a battery and connect the leads of your meter... one to each terminal. When you do this you will see a voltage reading. If you put both leads onto the + terminal of the battery you will not see a reading. This is the same as putting both probes from your meter onto the switch when it is on.

As for the backwards wiring, That is an issue that needs to be looked into more. It could be someone did in fact switch the neutral which is not good. It also may be that someone who did not know what they were doing used the white wire as a hot. You should start to investigate this circuit right from the panel box. To see if the white is the hot or neutral you can probe with your meter between the black and ground wires and the white and ground wires. If you see voltage between the black and ground wires then it is the hot. If you see voltage between the white and ground then something, somewhere is messed up real bad.