Lights turned themselves on, won’t turn off

[jeepwm69]

Chandelier in our dining room was on this morning. It’s on a dimmer so I figured switch was bad. Completely removed switch and the lights are still on.

Obviously I have a wiring issue, and I’m pretty good with DC wiring but not sure what I should be looking for here.

In the meantime I have the fuse pulled.

Any suggestions on what I should be looking for?

 

[3baygarage]

An exorcist.


J/k

 

[Shiftless]

Can we assume that nobody has been recently doing electrical work on that circuit?

Can we also assume that the chandelier and its dimmer switch have been operating normally for a number of years? You said “fuse” so that hints at an older installation.

Do you have wiring in the attic or wall that has been chewed on?

Has the weight of the chandelier affected the wiring in the electrical box to which it is attached?

 

[Jim greengo]

How many wires are in the switch box? If there's only 2 I'd say it's only a switch leg,and your problem is somewhere inside the box the fixture is mounted to.

 

[jeepwm69]

Two wires going to the switch. House was built in 1948 so yes electrical is old.

I did remove the collar where the chandelier mounts to paint the ceiling last week, but have already pulled it back down and pulled the wiring out of the ceiling box to make sure it wasn’t a connection issue there.

Going to get into the attic now and see if I find any chewed wires. I did find evidence of mice a couple of weeks ago and I’ve set traps but haven’t caught ant yet. They did steal the bait one trap in the opposite end of the house

 

[MikeF2316]

I would suggest posting a picture of the switch box with the switch removed, showing as much detail of wires, connections and colours as possible. See if you can include enough detail so we can see which wires are from which cables.

Repeat for the light fixture box.

If you have only one cable, two wires, a black and a white in the switch box, then those two wires connected together anywhere from there to the light's box can be your problem.

 

[Sandyshain]

Is there a second switch somewhere?

 

[jeepwm69]

Couldn’t access the wiring from above without tearing up decking, so tried something else.

Took chandelier down and hooked up an outlet to the two wires (black and white). Plugged my kid’s hairdryer into it and turned it on, and then went to the fuse panel and screwed in the fuse.

Nothing.

Went to the room, touched the switch wires together and the hairdryer came on.

This led me to believe that there was an issue with the chandelier itself. Trimmed off excess wire that was originally looped around the mounting bracket and reconnected to the black and white wire coming out of the ceiling.

When I screwed the fuse back in the light came back on with switch wires still not connected.

I began to trace the wire From the ceiling down to where it goes into the arm on one of the lights, and when I began messing with the arm the lights started flickering. The fixtures screw into place on the end of each of the arms and when I unscrew that one a little bit the lights went out. I walked over to the switch wires and connected them and the lights came on.

Again I am most familiar with DC wiring but it appears to me that hot is run directly to the light and ground is run in a a loop to the switch. My hypothesis is the fixture is being grounded through the metal of the chandelier itself when that fixture is tightened down, possibly from a bare/ pinched wire, but it’s been hooked up this way for 40-50 years. It appears that neutral is backfeeding through the body of the fixture when I tighten up that particular part of the chandelier arm, but I’m wondering if this is a hazard if I merely loosen the arm? Works fine like that and has been that way for decades. Am I correct that the box should not be able to provide a neutral for the fixture? Should I be concerned that it apparently is?

 

[Bert_]

I'd like to see some pic's. It is very common to see switched neutrals pre 50's wiring. Sounds like you have a least one fault, since it's on the neutral side it doesn't blow the fuse but it is still an issue and needs to be corrected.

 

[Richard Cranium]

Your light Is switched through the neutral wire, and you have a bare wire that is grounding out the circuit in your light fixture.

 

[Shiftless]

Your light Is switched through the neutral wire, and you have a bare wire that is grounding out the circuit in your light fixture.

to that ^^^^^^^^^^^^^^

That makes perfect sense to me. I bet that’s the problem. Put up a new light fixture and wire the switch leg to interrupt the BLACK hot wire this time instead of the neutral. Don’t forget to pull the fuse first!

 

[jeepwm69]

Your light Is switched through the neutral wire, and you have a bare wire that is grounding out the circuit in your light fixture.

Makes sense.
But even if a wire grounds against the fixture, should the circuit be completed? That would mean the box itself is grounded right? On a two wire system that would imply that the neutral is bare/ touching the mounting box somewhere. Is that an issue if we remove the light fixture from the equation?

 

[MikeF2316]

There are multiple levels of safety in modern house wiring. Your light has one of them compromised. Your old wiring with a switched neutral has another. I think insulation is breaking down inside the legs of your light fixture. It's only a matter of time until there is a bigger problem. Either replace the fixture, or replace all its internal wiring, and fix the problem with the switched neutral.

You can think of AC (house) wiring just like DC (car) on this type of circuit. The only difference is house wiring has lethal voltage, so you never switch the neutral (ground in car wiring).

 

[bad_idea]

Household current has three wires - hot, neutral, and ground. Think of the hot as positive in DC and neutral as negative in DC. The ground should never be used, it is a safety. Everything is grounded - the fixture, your outlets, the electrical boxes, any conduit, the case of the electrical panel, all of it. Current wants to go to ground. If something screwy happens the current travels down the ground wire to ground. If there is a fault without a ground then you become the ground when you touch it.

Your switch is wired to interrupt the neutral wire. That is not allowed these days, you are required to interrupt the hot wire. Interrupting the neutral leaves the fixture energized looking for a way to release that power, any path it can find. Not saying you have a hazard on your hands, nothing world ending, just not the best circuit design.

I would suggest you replace the fixture and rewire the switch to interrupt the hot lead. Simple fix that can be done within the fixture box by swapping a couple wire nuts around. I myself am a jeep guy and know DC much better than AC. I have picked up a few things along the way as needed.

 

[Engineer61]

Do you have metal conduit running to that electrical box and individual wires instead of some kind of romex? That box would be grounded through the metal conduit, allowing the circuit to complete.
This wouldn't be typical construction for a house, but in 1948 the post-war building boom was under way, lots of workers and companies that had only done commercial building switched to building houses and materials were often in short supply so what workers were used to using and could be found & purchased is what was used to build houses.

 

[Viper98912]

To me, it sounds like something has broken inside the fixture (probably the neutral, whether the wire itself or one of the sockets) and is grounding itself through the fixture frame to ground.

Replace the fixture before something else happens and/or someone gets injured with live voltage.

 

[Jim greengo]

Your light Is switched through the neutral wire, and you have a bare wire that is grounding out the circuit in your light fixture.