Flickering Circuit Test Light

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Old 12-13-14, 11:43 AM
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Flickering Circuit Test Light

I'm doing some renovations in my kitchen and the counter top lights (located under the top cupboards) are not working now

These lights are controlled by a switch and they were working yesterday but I have no idea right now why they are not working. I removed the switch and tested the 2 ends of the black wire with a circuit test light and the light on the circuit tester is flickering

What does it mean when the circuit tester light flickers?
 
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Old 12-13-14, 12:04 PM
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A circuit test light is not a terribly effective way to troubleshoot a problem.

What you need to do is to check from each black wire to the box. One should show 0v and one should show 120vac(lit up). Then you need to check from the black wire you found hot to the white wire connection in the back of the switch box.
 
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Old 12-13-14, 12:40 PM
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Thanks Pete and Happy Holiday to you too

Your right about the circuit test light but since the lights were working yesterday I thought it was something simple. I will do as you say tomorrow
 
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Old 12-13-14, 09:31 PM
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Sorry Pete but I don't really understand what you say:

“check from each black wire to the box” which box are you referring?
 
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Old 12-13-14, 11:03 PM
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You need to test from the wires to ground. if it's a metal box... then the box should be grounded.
 
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Old 12-14-14, 04:16 AM
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If you don't have a neutral in the box (true of some switch boxes) test results from a current carrying conductor to ground (such as the metal box) may be made and taken with a grain of salt (since you have to assume that the metal box was properly grounded).

If you don't have a neutral then a more reliable reference to test conductors for voltage measurements is a long wire (single conductor 14 gauge such as THHN quite nice) connected to the neutral bus in the main panel and stretched upstairs and across the floor to where you are working.

Testing across the terminals of a switch or across two wires that were unhooked from a switch does not give useful information to someone who is not extremely experienced in electrical matters.
 
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Old 12-14-14, 04:48 AM
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A polarized extension cord or an extension cord with ground plugged in to known correctly functioning receptacle can also be used as a reference point.
 
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Old 12-14-14, 05:56 AM
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I did the test with my circuit test light for both S1 and S2 and both are the same.

All boxes are metal and I do have the White wires in them. The light on my tester lights ON when I test one Black wire to the metal box and is OFF when I test the other Black wire to the box. Then between the hot Black and one White wire the light is ON and between the hot Black and the other White wire the tester light is ON but dimmed.

I have attached here a schematic to show all the circuit

What the test I did means?
 
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Old 12-14-14, 06:43 AM
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The box marked JB should have never been buried. This is a big no-no. Now you have no access to troubleshoot it.

Anyway, it's probably just a loose wire/poor connection at one of the wire nuts.
This is quite a few connections, and it would be easy for an inexperienced person to make a mistake along the way. This is more true if you fed both P3 and P4 with 2 hot wires, one switched and one hot.
You need a meter to test this properly.
In the meantime, without testing for proper voltage: Inspect each neutral connection in every box. Remove wire nut, look at connection to ensure it is secure and no white wires were pulled up into nut too far or other problems. Replace wire nut with new.
Sometimes when connecting 4 wires within a nut (or greater quantity), they could be twisted too much, causing one or more of them to lose contact with the others.
This may not fix your problem, but it's a place to start.
 
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Old 12-14-14, 06:46 AM
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deleted
Also consider the first 2 sentences of the next post deleted since my computer is too slow for me to make the edits to that post also now.
 

Last edited by AllanJ; 12-14-14 at 07:01 AM.
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Old 12-14-14, 06:52 AM
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"The JB is now behind ceramics ..."

The junction box cover must be exposed (accessible).

When you saw the test light on bright when connected to the hot black, was it also connected to the white wire coming from the same cable as the hot black or from the other cable?

A bundle of white neutral wires should not be undone while the matching black wires are still connected to the switch or still in another bundle. This usually results in voltage on the downstream white wire (relative to a known ground or reference neutral) if there was a light or other load still plugged in and switched on.
 
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Old 12-14-14, 07:09 AM
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I'm aware of the regulation regarding exposed junction boxes but back in 2001 when I did the work I decided to hide it otherwise it would have been visible in the kitchen. Relocating this JB to another location would have involved removing cupboards. Not a good excuse but sometimes we got to do what we think is best under the circumstances.

In both S1 and S2 the tester light comes ON when I connect the Black and White wires from the same cable.
 
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Old 12-14-14, 10:23 AM
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In your first couple of posts you talked about a switch. Now there are two dead switched circuits.... one at each end.

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If P1 and P2 are working normally..... and by normally I mean with something plugged in... not a test light. Then the problem cannot be at the JB.

With my test you confirmed that you have voltage across the neutral and hot wires.
I would make sure I had a device plugged into P1 or P2 while making my tests. The device could be a simple table lamp turned on.

Your test light draws a minute bit of power to work. So if you had a poor connection... that light could show normal. By putting a load into the receptacle.... it eliminates the poor connection issue.
 
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Old 12-14-14, 11:35 AM
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Sorry about that Pete but now all is OK

By disconnecting the White wires to do your test, after I re connect them all halogen lights are now working. My conclusion is that when I pulled out the switches / plugs to do the wall ceramics, after I pushed them back the White wires on S1 or S2 moved.

Thank you all
 
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