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#191929 - 01/19/10 07:51 PM found solution regarding blinking lights  
mike collins  Offline
Joined: May 2005
Posts: 15
If anyone has read my previous post regarding blinking lights which intermittenly dim,the following is what I found.
First I would like to thank everyone who gave their imput and ideas.
After taking many voltage readings on each circuit between the neutral and the hot legs,I found one with a little higher voltage than the other circuits and of course I thought I found the problem. So I shut off that breaker and the dimming continued. After taking more voltage readings I found another circuit with a little higher voltage and realized I had found a symptum but not the problem.
Just by change I opened a metal box in the basement where there is a bell transformer, thinking maybe there is a faulty path in the neutral connection at the transformer. So after removing trans from the circuit I still had a problem. When checking the splices in this box I noticed the clamps holding the old romex in place where loose. No big deal right. Well then I noticed the ground wires where back wrapped around the old romex,making the box clamps a part of the ground splice. I also noticed a bare spot in the neutral wire,which probably was hitting the metal box.
Well to make a long story short, after unwrapping the ground wire and fixing the splice, the diming ,blinking lights went away.
I can not tell you how agravating it was to find this problem. All the devices in the rest of the house had been replaced and they were grounded properly, but just by chance this one box in the basement was not.
I think what lead me down the wrong path to diagnose this problem was the fact that I had just found a problem in another home where the power co. had lost a neutral on the pole, so I was convinced it was something outside.
Hope this post can help someone else.


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#191930 - 01/19/10 08:24 PM Re: found solution regarding blinking lights [Re: mike collins]  
sparkyinak  Offline
Joined: Jul 2007
Posts: 1,327
Good to here. Voltage problems are sometime a booger to chase down with a DMM. Anytime a neutral problem is suspected, I use a Wiggy type solinoid type voltage meter. I had an issue one time at a remote site when I showed and I got the, "Oh while you are here, we are having a problem with this piece of equipment" story. It was never called in so I came unprepared. All I had was my pouch and DMM. the machine was acting hinky and I suspected a neutal problem but the meter kept telling me that was getting good voltage. I was wishing really hard for my wiggy. Instead of charting a float plane to retrieve my meter, I found and old relay (solinoid) of the right voltage. Although the relay would work on a known good circuit, I could not get it to fire in the machine every time I went to the neutral. It turned out that i had a bad neutral switch in the breaker. I got 120 volts with the DMM but nothing for the relay on the load side of the breaker. Since then, I carry my wiggy in my pouch.

Last edited by sparkyinak; 01/19/10 08:25 PM.

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#191934 - 01/19/10 10:25 PM Re: found solution regarding blinking lights [Re: sparkyinak]  
Texas_Ranger  Offline
Joined: Dec 2001
Posts: 2,402
Vienna, Austria
Yeah, solenoid type testers are real helpful!
In Germany they even tell you not to touch line voltage wiring with a DMM because you're almost bound to get weird readings.

#191937 - 01/20/10 02:31 AM Re: found solution regarding blinking lights [Re: Texas_Ranger]  
EV607797  Offline
Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
Call me forever a skeptic, Mike, but I'm not buying this as the solution. You may have narrowed your search, but I don't think what you found is truly the cause for such flickering.

I don't see how you could have been getting different voltage readings from different breakers. They are all connected in parallel at the bus bar, so aside from a minuscule difference between the upper and lower ends of the panel, this couldn't have been possible. All odd-numbered poles would measure identically, as would the even-numbered ones. OK, one exception might be a bad breaker with burnt contacts inside under load.

A fault in a doorbell transformer winding wouldn't have caused flickering lights either. These things draw less wattage than a light bulb, so even a bad one couldn't cause that. If anything, a fault would cause the primary windings to blow open and just stop working.

A ground and neutral touching in a single box can't do this either. If anything, the circuit feeding this box had/has an open neutral between it and the panel. In such an instance, the nicked neutral touching the box could have caused the ground wire to become a current-carrying conductor. With poor connections to the box as you stated, that could have been the cause for the flickering. Still, you'd have seen evidence of heating at the point where the neutral was touching the box.

Unless most of the building's lighting is on this one circuit, only the most extreme circumstances would have caused flickering on other circuits. Personally, I think that the lighting circuit's neutral wire has a break, likely at where it connects to the neutral bar in the panel. People often over-tighten these screws, causing them to literally cut the wire or crimp it down to the equivalent of a much smaller gauge. It appears and even feels intact even when it isn't.

Let's not rule out a "double" trouble. There may be a loose neutral wire elsewhere, such as in a receptacle or (gasp) a buried splice. The neutral/ground cross that you found may have been carrying part of the the load while the faulty device is working just fine. Power is coming in but not going back out. I know you said that all of the wiring devices have been checked, but there could always be that one that was missed.

I hate to sound like a turd in the punch bowl, but I suspect that the problem is on the way to being fixed yet not completely. You are definitely on the right track and a faulty neutral is often the first place to look.


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#192301 - 02/06/10 10:18 AM Re: found solution regarding blinking lights [Re: EV607797]  
mike collins  Offline
Joined: May 2005
Posts: 15
You were right. I thought the problem solved but got another call and went back.
As stated in previous post I had checked the mter socket had power co. replace splices at w.h. so I decided to run a single piece of wire from the panel neatral bar outside to the guide wire supporting the pole in the street and no more dimming and blinking.
So I took the meter out of the meter socket again and the neutrals, both copper looked fine. I removed both wires from their terminations and relized they needed a good brushing with steel brush and sand paper.
After checking the voltages back at the panel I did not get the fluxuations I had before and everything has worked fine since.
My previous fix must have been a coinsidence especially where this was a intermitten problem.
Thanks again for your time and comments.


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