Switch Loop Problem

CookeCarpentry

Hi all,

New to the forum, and normally would call my electrical sub for this (most likely very simple) question, but unfortunately he is on temporary disability with a hernia this week.

The in-laws house: there are a row of recessed lights fed directly from the panel with a switch leg or switch loop to a single pole switch. Power enters from the fixtures first, then to the switch. In the box, there is a white, black and ground - the white and black are registering hot, can't get the dimmer switch to work. Tried replacing the dimmer, still no luck...is there something else going on here? Or is there something simple I am overlooking?

Celtic

Is this a new dimmer you are installing?

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kasey

I take it that when you say the black and white are hot that you are saying that the switch has a two wire romex plus ground coming up from the dimmer and that the white from the dimmer is the feed to turn on the lights and the black is coming from the panel via the first recessed can and feeding the switch.

If this is the case and you are getting normal house voltage from both wires the switch should be working okay. What might be the problem is a loose connection up in the first can; either the feed from the dimmer(which would be hooked into the black wire from the can), or the white neutral from the panel (I also take it that none of the recessed lights are working at all).

By the way, while you don't need to mark the white at the dimmer itself
up in the can's junction box you might want to mark the white just to show somebody else who might need to get up there that it is being used as a 'hot'. I usually do this by coloring it black with a sharpie marker.

Celtic

What does 200.7(C)(2) say about "usually"?

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CookeCarpentry

Kasey and Celtic.

Thanks for the replies. To answer your questions:

None of the recessed lights are working...my father-in-law is now claiming the feed is coming from the panel, then to a couple receptacles and then the lights, and terminating at the switch. (this "addition" was a hack job, at best).

I removed the switch, line voltage on both white and black, thought it might be a bad dimmer, replaced the dimmer, still no lights. Tomorrow, I am going to remove the receptacle and see how the junction was made...already checked the neutral connection at the panel.

If it is the recessed lights...no clue how I am going to access them, they are the 3.5" or 4" low voltage, high intensity halogen (new construction housings)....

FYI...the white was striped with a black marker...about the only up to code thing done in this wiring mess.

I'd still welcome any more input, thanks so far...will update whenever I get around to the in-laws to check it out again.

Celtic

If that feed was running though recept., there is a chance the recept. were switched and someone screwed up the splicing.

If you attempt to install a dimmer while the circuit is "hot", many times it will cause the dimmer to be DOA.
Don't know if you did that...either way, now you know.

Pictures!

It's a PITA...drop lamp and trim, unscrew housing from frame - drop housing [aka..hold to the side]..access the JB.... Good f'n luck seeing what's going on in that JB.

Did I mention we'd like some pictures?

Good luck...hopefully it's just a screwed up splice at recept.

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mickeyco

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Some people climb mountains. I take out the trash. But we both do it for the same reason.

kasey

sometimes I mark it with black tape if I don't have my sharpie handy.

kasey

You wrote, "I removed the switch, line voltage on both white and black,"

If you take out the switch, there is no way that you should be reading both wires as being hot. That is the point of a switch, to break the hot line traveling to the power side of the light. If you have power coming down both wires to the switch I'd say somebody f'd up something in the junction box of the can that is switched.

When did your father-in-law realize this wasn't working? Had somebody else been doing work on it?

knothole

Hot on both wires + closed switch = POW

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boman47k

No sparky here, but if both lines are hot, it would throw a breaker when the switch is closed. How did you determine both black and white are hot?
Did you test from black to ground and white to ground? What are you using to test with?

Seems you said it was tied into some rec's. They all working?

Celtic

Even if they are the same phase?

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CookeCarpentry

Thanks for the input, so far. Still no chance to get over there, otherwise I would have pictures, so bare with me until then.

As best I can tell, the feed comes from the panel, to a handful of receptacles (2-4) which are all working fine. I assume at the last rec. the feed climbs the wall and into the ceiling to feed power to the first of 4 recessed lights, and then a switch loop drops down into a single gang box with a dimmer.

I checked the subpanel - the neutral and ground go to separate terminals on the bus bar. All receptacles are hooked up correctly and functioning when the breaker is on. All four lights are out.

I removed the original dimmer (power off before doing work), thinking it was a bad switch, installed new, and still no lights. A tick tester indicating, when the switch is uninstalled that both white and black are hot. Continuity tester is indicating everything is fine. I am 100% certain my in-laws were not working on anything, given the fact I had to peel about 9 layers of paint off the switch to remove it.

I am open to other suggestions (and am also suggesting my FIL call an electrician because I am tired of dealing with this).

As far as the switch loop is concerned, I thought the white and black were always hot, and the purpose of the switch was to interrupt that connection to turn lights off or on...I am incorrect in this??? Just FYI - this is only the 2nd switch loop I have seen in 10 years...apparently not common in eastern PA.

Thanks again everyone.

boman47k

Just FYI - this is only the 2nd switch loop I have seen in 10 years...apparently not common in eastern PA.

Hmm, I have already said am no sparky. Now I may really show my ignorance in this area, but what is used where there is no loop?

CookeCarpentry

We both may be at the same ignorance level....this is what I think of when I say a switch loop: the power goes into the fixture first, with the wire run terminating at the switch location" as compared to the more common method (for single pole switches) of power entering the switch location and then feeding the fixture(s)

mickeyco

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kasey

I may be misunderstanding what you were trying to say previously. I'll explain again what I was trying to say before. I understood you to say that with the switch disconnected (both wires off the switch and hanging free), you tested each individual wire and both read line voltage (115-120v). I'm assuming you put one lead on ground and one on the black and then repeated it for the white.

Now as said before, if you do have this taking place there has to be something messed up in the junction box of the can. You should read line voltage on one wire and nothing on the other, that's because the switch is supposed to bridge the break in the line. You've got power from one wire going down to the switch (feeding only one terminal). The other wire on the second terminal then goes to the light itself. This should be dead until the switch is turned on.


I also noted that you added that the lights are low voltage lights. Are they old? Maybe the transformers shot.

Also, did you look in the junction box of the can yet? I assumed you had. This is crucial. You have to get in there and see if you have voltage coming back up into it. I think you will. I still believe it is a loose connection or, as I just mentioned a transformer.

mickeyco

Even more so, you'll get like 2 POW's, POW, POW, like that.






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CookeCarpentry

Kasey - now we are on the same page - bit of a communication misunderstanding. I should back up like three steps...

The cans are low voltage, 3.5"-4" halogen, new construction. I can't get access to the jb by the can, unless I break a hole in the ceiling. I was basically trying to test every scenario before doing that...I'm 99% positive it is a connection problem in one of the fixtures but the amount of joint compound around each can, as well as my father-in-law telling me he applied drywall adhesive to the metal of each can before installing the drywall, makes it hard to move the fixture over....regardless of the fact that these fixtures are hard enough to access without all of that crap..

More, or less, I realize it is most likely a problem in the fixture, but don't want to get into tearing the ceiling out in four locations and wanted to run the situation by some others to see if there was any preliminary problem solving solutions I overlooked.

Celtic

+ YouTube Video

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