I have a short run of three conductor wire in a bath that is run from switch to fan light combo. (Hot lead comes into the switch.) I can get either the fan or the light to work fine but both trips the breaker. I have visually confirmed the wiring both at the switch and at the fan/light. and I can get continuity on both circuits
I suspect my BIL got nail and/or drywall screw happy and has shorted across the red and neutral leads. Any suggestions short of telling him we have to rip into the drywall? I’d love to know for sure if there was a way to test for it 1st but at this point it looks like thats the problem.
There isn’t a prayer of fishing a new wire without doing damage. The bath is on the second floor of a story and half house. My only hope probably going to be to go behind the trim and “route” a space in the door frame with my circ saw and then run the new wire in conduit up to a point. we can actually fish it.
Replies
See if I got this.
You can trun on the fan but when you turn on the light cb trips.... and you can turn on the light but when you turn on the fan the cb trips.
That it?
I should have been clearer. The red lead is definitely the problem. The black lead works. I used the black lead to test both the fan and the light to make sure they were okay. Anytime the red lead is hit it trips the breaker.
OK, that makes more sense. Just to confirm, if you have a meter of some sort, disconnect both ends of the cable and check for continuity between each of the 4 wires. There should be no continuity showing. From the description you have a short from red to white or ground.Like I said, you can use a "non-contact" voltage detector (even one of those Christmas tree light testers) to find the specific nail that did the dirty deed (wire red to hot and leave the other wires disconnected on both ends, then check each nail/screw with the voltage detector). Then you could cross your fingers and remove the guilty fastener (after disconnecting the power!!) and hope that the wire wasn't seriously damaged to where it would fail in the future.But better to just grit your teeth and replace the wire.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
(And I'm betting in the future you'll be more cautious about getting wires set back from the front of the stud as required by code, and using nail plates where that isn't possible.)
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I suspect my BIL got nail and/or drywall screw happy and has shorted across the red and neutral leads.
If I'm reading this correctly, then a short across the red and neutral would cause the breaker to trip when whatever is connected to the red wire (fan or light) is turned on. Similarly, a short between the black and neutral would cause the breaker to trip when whatever is connected to the black wire (fan or light) is turned on. Finally, a short between the red and black would cause both devices to work whenever either switch was turned on.
Double check your wiring in the switch box. White from feed to white in 3-wire cable. Black from feed to common screw on switch. Black and Red from 3-wire cable to remaining terminals on switch, assuming duplex switch.
This should keep you busy until a real electrician comes along...
Bob
"I can get either the fan or the light to work fine but both trips the breaker. I have visually confirmed the wiring both at the switch and at the fan/light. and I can get continuity on both circuits"
Need more details about you can make one work and not the other.
Since you have a continuity tester have you checked for a short between the different combination of wires?
William the Geezer, the sequel to Billy the Kid - Shoe
Have the DW screws/nails been mudded yet? If you can see them you could always hold a tick tracer (at least that's what they call it around here) to the screw heads to see which one is causing the circuit. If you find the offender you could, wearing rubber shoes, gloves, and an insulated screw driver, back out the screw and see if that solved your problem.
You can use a non-contact voltage detector to see if there is voltage on one of the screws. The cable has to be energized, though, and if there's an apparent short between hot and neutral the neutral should be (temporarily) disconnected at the supply end.
But if fan and light work individually but both together trip the breaker I'm guessing there's some sort of wiring error, though I haven't figured out what it might be. Kinda sounds like one of the switches is wired to neutral.
Kinda sounds like one of the switches is wired to neutral.
But if that were the case, then the switch that is wired to neutral would consistently pop the breaker, but the other one would be fine. I'm glad that I'm not the only one that can't wrap my head around this...:)
Bob
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Yeah, but otherwise I can't see how it pops a breaker.I guess I'd first want to be assured that he's using 2-way switches, not (for some mysterious reason) 3-ways. And if he's using a duplex switch then I'd want to be sure that the hot supply is on the common screw. And of course at some point it would make sense to disconnect both ends of the wire and use a continuity checker to see if there's a short.I'd also be curious to know if, with both switches off, the light is glowing dimly or the fan running at low speed.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I'm not using three ways switches and not even a duplex in this case. Its just two singles in the same box with a jumper between (or I might have wired a jumper to both from the hot lead)
Use your continuity test to measure between the red and ground and the red and neutral. Have both end disconnected.One or both of those will show continuity if there is a nail shorting it out..
William the Geezer, the sequel to Billy the Kid - Shoe
" And of course at some point it would make sense to disconnect both ends of the wire and use a continuity checker to see if there's a short."
Theres the tip I was looking for. Never occurred to me to disconnect all the leads and still look for continuity. I'll do that this weekend.
Thankfully, the bath isn't done yet.
Ya may have the light wired to one side of 240, fan switching neutral to the other side of 240. When both are on, ya trip the light breaker.
Lotsa other possibilities, ohm everything out, voltages, etc..
I've seen that sort of mess in old K&T homes, with 3-way switches. But then the lamp blows in short order, without blowing the breaker.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
Ya may have the light wired to one side of 240, fan switching neutral to the other side of 240.
Based on the OP, I made a few assumptions - new romex, 2-wire feed into switch box, 3-wire from switch box to fixture. Unless neutral is wired incorrectly prior to switch box, 240 wouldn't be present. If it were, that fan would be spinning nice....
I was working on a job a number of years ago, where the customer did a lot of DIY wiring. I plugged my (then corded) Rockwell 3/8" drill into an outlet and pulled the trigger. Sparks showered from the brushes on both sides. A quick multimeter test showed 220V at the outlet. Apparently, the customer couldn't resist the $0.50 price for the duplex receptacle, and re-wired his nearby window air conditioner with a plug to fit...
Bob
>>>Apparently, the customer couldn't resist the $0.50 price for the duplex receptacle, and re-wired his nearby window air conditioner with a plug to fit...Somewhere, someplace, there is a village looking for an idiot....Scott.
It is indeed two wire with ground new romex into the switch box with three wire from the switch box to the fixture.
Disconnect the fixture and try it- if the breaker still pops, look at how the switch it wired vs how it should be. If the neutral is on the switch at all, it's wrong unless only the neutral is being switched and last time I heard, that's not right.
Neutrals are all ganged and wire nutted together on both ends.
Like I said just a few posts ago ( I know should have stuck around but couldn't), I used the balck lead to power either the fan or the light and either one will work from the black lead but the red lead pops the breaker.
I could just wire both of them to the black lead and tell him I know he eats a lot of mexican so its a code requirement.
I'd be leery about leaving the guilty fastener in place and just abandoning the red. Especially if it's a DW screw, the screw threads could over time cut through insulation on the black wire. Even with the fastener removed it's not really kosher (you don't know how badly the current-carrying capacity of the wire may be compromised), but it would be reasonably safe in this case where the load will never exceed a couple of amps.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I am certainly leaning to replacing the entire thing. It will be an inconvenience but safer in the long run. I am pretty sure we did the setbacks alright but the BIL is a use what ever comes in handy guy. If two and a half is what comes out of his bag, 2 1/2 is what he is going to use. Same with finish nails and he isn't real worried about occasionally overdriving here or there.
Heck, it could even have been me with an errant wire staple someplace. But in the end, yes, I will pay even more attention to it in the future.