3-[way] switch intermittently working

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  #1  
Old 05-28-14, 06:50 PM
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3-[way] switch intermittently working

A few days ago, I threw one of two 3-pole switches and the lights failed to come on. Flick-flick-flick---still nothing.l The second 3-pole switch did not do anything either. We were on our way out for a few days, so I did the minimum swearing necessary, opened the breaker, and left.

Upon returning, I closed the breaker and tried both switches. The lights turned on and off repeatedly—no matter what I did, the switches acted correctly.

I turned off the power, pulled every relevant cover, and inspected the wiring. That is, I pulled the covers off the switches, the junction boxes, and all five fluorescent fixtures. All switches were wired via their screw terminals (i.e. not the push-in connectors), and all wire nuts were tight. Other than visual and jiggling things to test tightness, the only checking I did was to ensure that the grounds were still connected (i.e. I used a continuity tester on a ground wire and the box/EMT). No, wait, I also used a rubber mallet to lightly tap around the boxes and the stud one of the switches is attached to in order to see if there was a loose connection despite my inspection. But when doing so, the lights didn't even flicker.


There are two other branches on this circuit, but because they’re pigtailed on (apologies in advance for improper/imprecise terminology), if they failed they theoretically shouldn’t affect the switches. I did open the junction boxes where they connect to check that the wire nuts were still tight.


These are new circuits (about eight months old), so it’s unlikely that the switches have failed from use. They’ve also worked flawlessly until this time, so there hasn’t been an issue all along (AFAIK).


So ... now what? Assuming everything is properly grounded, is it safe to leave the breaker on? Are there any additional diagnostic steps I can take?


Thanks
 

Last edited by ray2047; 05-28-14 at 09:28 PM.
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Old 05-28-14, 07:38 PM
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Are you talking about 3-way switches? Are the lights flourescent? I know you put out a lot of info, but more is needed.

Thanks.
 
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Old 05-28-14, 08:23 PM
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Yes, I'm sorry for sloppy terminology. There are two three-way switches. I have 2-wire Romex (black, white, ground) going to the first switch, and 3-wire (black, white, red, ground) going between them. The fixtures are basic fluorescent light fixtures. If it makes a difference, the links are to the actual items I purchased, not just examples.
 
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Old 05-28-14, 08:25 PM
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Welcome to the forums.

Your "problem" is not one of grounding. Your circuit would work the same with or without the ground. The grounding system is in place to protect from shorts. If you had a shorting problem you would have a tripped circuit breaker.

You could have a loose connection or a problem three way switch. The problem may reoccur but I don't think there would be a problem leaving the power to the circuit on.

As an electrician, if I did that work and had been called to come back, I would replace both three way switches to eliminate them as a source of the problem.
 
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Old 05-28-14, 08:56 PM
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Thanks.

I didn't think there was a loose ground per se, but I wanted to check the ground for a couple reasons. Primarily because if there was a loose-wire problem, I wanted to be sure that if it went from 'loose-wire-opening-the-cicuit' to 'loose-wire-touching-a-box" or something like that all the grounds were doing their job (as best as I was able to check).

My other rationale was because at this point I wasn't about to undo all the wire caps, just tug them lightly to ensure they were still tight. I used the ground wires as a proxy for the internal connections of the others. In other words, if one of the eleven grounds I checked wasn't making contact, I'd have gone through the effort to undo/redo the existing wire caps. I know that's weak proof (if at all), but I wanted to list everything I'd done.

Another detail I left out--sorry if this should have been in the OP--it's a GFCI breaker. I opened/closed it several times and pushed the test button (and reset it) several times.

I'm going to replace the switches tomorrow, but I still feel weird. Here I am, a minimally experienced DIYer, ostensibly blaming a switch. I get that it's possible, but it's just ... weird. I mean, which is more likely, that I got one out of x bad switches or I screwed up one out of 33 wire caps?



I'm sorry if this is too much information or over-explanation; I don't know what's germane.
 
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Old 05-28-14, 09:04 PM
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No need to apologize. Too much information is better than not enough.

It only takes one bad three way switch to mess with the circuit and I have seen them defective.
 
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Old 05-28-14, 09:33 PM
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Again, thanks---and thanks in general for all the help on the forums in general!
 
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Old 05-28-14, 10:04 PM
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If this is newer there is a good chance the them breaker is an AFCI, not a GFI.
 
  #9  
Old 05-29-14, 07:04 PM
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So I replaced the two switches with a pair of Leviton "preferred" 3-way switches (they're not their 'commercial' line, but a step up from the base switches I had in there). I marked the two I pulled and left them on my workbench for now.

There's no easy way to open them that I can see, but I imagine a few minutes with a Dremel would let me see inside. Is it worth the five to ten minutes? That is, any chance a visual inspection will show a weak contact or whatnot? Or would the act of ripping them apart itself wreak such havoc on their insides as to mask any pre-existing fault. Basically, I'd love to see something, so I can fully relax into complacency again--as in 'oh, so it really was the switch!'


Oh, and since these are in an unfinished basement, I went with a GFCI breaker instead of an AFCI.
 
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