Author Topic: Home Wiring Issue  (Read 3436 times)

Daley

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Home Wiring Issue
« on: August 06, 2015, 08:18:08 AM »
I was switching out some incandescent bulbs for Cree LEDs in a multi-socket light fixture for a friend recently and ran into something odd: the LED bulbs wouldn't turn off at the light switch, only go dim. When it was 100% incandescents, the incandescents appeared to be off when the switch was off, but 100% LEDs simply will not turn off. If you combined an LED with an incandescent, the LED would go off as well.

I checked the wiring, here's what I've got, and it's all reasonably modern 3-strand (neutral/hot/ground) TPS cable. On the north side of the ceiling box (coming from the light switch and breaker box side), there's two sets of wiring coming in. On the south side, one set of wires. The circuit powering the ceiling light also powers all the wall outlets in the room, and I'm unsure of where the south side wiring extends off to in the ceiling, but I suspect the back porch light if I were to take a guess. I also haven't undone all the wiring to figure out which run specifically goes to the wall switch for this ceiling light.

Right now, here's how it's wired. For the sake of perspective and understanding looking up into the box, we'll label the northwest wire run (1), the northeast wire run (2), and the south run (3).

-(1) black/hot wire is connected to the light fixture.
-(1) white/neutral wire is connected to the black/hot wires on (2) and (3).
-white/neutral wires on (2) and (3) are tied together and connected to the light fixture.
-ground from (1), (2) and (3) are all tied together in the box.

I figure (1) is the run to the light switch.

The multimeter still registers the fixture wiring as hot even in the off switch position (obviously), but it's clearly got some resistance in the line and isn't anywhere near full power. A part of me also wants to say from what I understand of electrical wiring, the wiring looks right to me for what's being done, but I am not an electrician. After sleeping on it and typing this out, I'm starting to suspect my initial gut feeling that the wall switch is failing is probably correct, but I'd like a second and third opinion on the wiring and situation before trying to swap it out as it's buried behind a 1/4" sheet of well adhered fiberboard backsplash that only had the minimal amount of cutting out done for the light switch to poke through and get the cover screwed in.

So, could it be screwy wiring or just a faulty/failing switch?

Photo attached of the ceiling box. Thanks in advance!
« Last Edit: August 06, 2015, 08:21:03 AM by I.P. Daley »

laughing_paddler

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Re: Home Wiring Issue
« Reply #1 on: August 06, 2015, 08:27:57 AM »
I think that LED bulbs will often need an LED-specific switch, or one that is rated to drive the LEDs on a dimmer. Should be able to find that at a big box store.

Daley

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Re: Home Wiring Issue
« Reply #2 on: August 06, 2015, 08:29:27 AM »
I think that LED bulbs will often need an LED-specific switch, or one that is rated to drive the LEDs on a dimmer. Should be able to find that at a big box store.

No dimmer is involved here, just a hard on-off switch.

This also wasn't the only fixture in the house switched from incandescent to LED, and the others work fine.

Thanks anyway.

waffle

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Re: Home Wiring Issue
« Reply #3 on: August 06, 2015, 09:12:12 AM »
If it's still registering as hot when its off then you need to check out the switch. It may just be worn down and not fully disengaging or its wired wrong. I have several LED light fixtures in the house and they all work with  very basic $2 switches. It's a really simple and cheap fix. If the switch is new and wired up right then start looking for other culprits (is there more than one switch on the circuit)

Spork

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Re: Home Wiring Issue
« Reply #4 on: August 06, 2015, 12:55:28 PM »
Have you looked at the switch?  Is it possible there is a 3 way switch here?  Specifically I was thinking a 3 way where there is an unsuspected dimmer somewhere.

Daley

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Re: Home Wiring Issue
« Reply #5 on: August 06, 2015, 07:00:49 PM »
Okay, hacked away, got to the power switch and replaced it. Same issue. Removed switch entirely with no power, checked with ohmmeter at both ends, and found continuity with some resistance.

There is no other hidden/unknown/three-way switch.

At this point, it looks like there might be a short in the leg of wiring for the power switch. Still love to hear from any electricians in the community willing to read everything over and give a second opinion and confirm/deny. Any other bits of info needed, I'll be happy to provide.

Thanks!

worms

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Re: Home Wiring Issue
« Reply #6 on: August 06, 2015, 11:43:02 PM »
I am not an electrician in any way, but what stood out for me in your post is that the lighting circuit also is powering a couple of sockets.  That would be against the rules here but might be allowed where you are.

I wonder if the way to make that combination safe was to have the light switch simply as a relay (on a separate circuit with a lower rated fuse) rather than on the actual circuit itself? You could have a separate enclosed switch (controlled by the relay) and it is arcing in that which is giving sufficient power to light the LEDs.

Spork

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Re: Home Wiring Issue
« Reply #7 on: August 07, 2015, 07:36:29 AM »

At this point, it looks like there might be a short in the leg of wiring for the power switch. Still love to hear from any electricians in the community willing to read everything over and give a second opinion and confirm/deny. Any other bits of info needed, I'll be happy to provide.


I'm with you on this one.  Someone's probably put a nail through it.  You can disconnect the wiring at both the switch end and the light end and see if your multimeter shows continuity between the wires when they're not connected.  That would pretty much cinch it for me.

Re: lighting and receptacles on the same circuit:  That's totally normal around here.  (Caveat: I do not know electrical code, but sort of "monkey-see-monkey-do the electrical code.)

Daley

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Re: Home Wiring Issue
« Reply #8 on: August 07, 2015, 08:13:07 AM »
At this point, it looks like there might be a short in the leg of wiring for the power switch.

I'm with you on this one.  Someone's probably put a nail through it.  You can disconnect the wiring at both the switch end and the light end and see if your multimeter shows continuity between the wires when they're not connected.  That would pretty much cinch it for me.

Exactly what I'd done yesterday. When you have an air gap between leads on both ends of the wiring and you're still getting continuity, one begins to suspect something hinky. You're probably right, it's probably an errant nail. Of course, it's probably been this way for years, but unnoticed due to the incandescent bulbs. Better to be found now and fixed.

I'll also have to remember for future use that Cree LED bulbs can make fantastic short detectors on switched AC circuits.

Rural

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Re: Home Wiring Issue
« Reply #9 on: August 07, 2015, 08:14:39 AM »

At this point, it looks like there might be a short in the leg of wiring for the power switch. Still love to hear from any electricians in the community willing to read everything over and give a second opinion and confirm/deny. Any other bits of info needed, I'll be happy to provide.


I'm with you on this one.  Someone's probably put a nail through it.  You can disconnect the wiring at both the switch end and the light end and see if your multimeter shows continuity between the wires when they're not connected.  That would pretty much cinch it for me.

Re: lighting and receptacles on the same circuit:  That's totally normal around here.  (Caveat: I do not know electrical code, but sort of "monkey-see-monkey-do the electrical code.)


I don't know the current codes, but lighting and receptacles on the same circuit was perfectly okay under the 2006 International Residential Code, to which our house was subject.


+1 on the likelihood of there being a nail in there somewhere.

paddedhat

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Re: Home Wiring Issue
« Reply #10 on: August 08, 2015, 10:46:32 PM »
As an electrician, I have run into incredibly bizarre issues involving motors and resistance loads acting as downstream "bridges" between hots and neutrals, that can result is some odd voltages and backfeeds. These are particularly an issue when there is a loose neutral somewhere in the system, AND the system was wired with  12/3 or 14/3 wire, where  two 120volt circuits, on opposite "phases" share a common neutral. By now I have probably lost a lot of you, but the first thing I would do is turn off any existing old style incandescent lamps that may be on the same circuit. Next I would look in the panel for any single breakers that appear to share a neutral, as evidenced by a single pole breaker connected to a red wire. Then I would confirm that every neutral wire lug in the panel is thoroughly retightened.

Your theory of a nail puncture may also turn out to be correct. I have done trouble shooting on a few of these, an they can be a real PITA to isolate, and correct. Good luck.

Jac123

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Re: Home Wiring Issue
« Reply #11 on: August 09, 2015, 08:32:23 AM »
I would have power company check for loose neutral on their end. It sounds like your having stray voltage trying to find ground.  Have you had trouble with lights blinking in the past?