Randomly Flickering Lights

natewallJuly 22, 2006

The lights flicker on some of the circuits in my house. Not horribly bad, but noticeable. I'm concerned about the computers we have, which are on one of the circuits that fluctuates. This is even with all large loads off in the house, like the A/C and drier. A volt meter verified at least a 5 volt drop when the flickering is happening. Its random and almost as if there is a short somewhere.

An electrician buddy come over and he tightened all the screws on the breakers pannel, including the neutrals, tightened the lugs from the meter that connect to the panel bus bars, and pulled the meter and verified everything was tight on that side. On the circuits that flicker he even switched their breakers to the other 120V line to verify if the line outside the house was fluctuating. Even switched breakers. Still does it and oddly, the same circuits flickered. We both are stumped.

He said it may be an internal problem where more than one circuit is sharing a return and there is a loose connection somewhere on that return, or the main 4-breaker set might be the trouble (the breaker box is about 35 - 40 years old). He suggested opening up all the electrical boxes on the flickering circuits and making sure all connections are tight.

I had the electric company come out and they said the voltages check out coming into the house, but like I said, the flickering is random, sometimes it won't happen for a couple of hours, they may have missed it.

Any ideas?



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How many circuits? If it's more than a couple, there's no way it can be a floating neutral. But it is a loose connection somewhere. If it's about half of your circuits it's a little easier to understand. You mentioned checking everything up to the meter. Does your panel include a pull section on the electric company's side that has been 'locked'? If so, check the lugs in there.

    Bookmark   July 22, 2006 at 1:39PM
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I can assure you that it's not a short. I don't mean to hurt your feelings or anything, so I hope you'll take this in the spirit intended - a constructive one.

A short circuit is a very specific failure. Depending on where it occurs in the circuit, it may result in the opening of a fuse or a circuit breaker if these devices are properly installed, but it can also cause a fire or injury if they are not. Or, it may mean that a light won't turn off.

My point is that calling nearly every electrical failure a "short" often demonstrates that one has no idea what a short circuit is. As the old saying goes, it's better to keep one's mouth closed and appear ignorant than to open it and remove all doubt. ;-)

When you're describing such a problem as this to an electrician, I suggest that you detail the symptoms as thoroughly as possible, and let the pro draw appropriate conclusions as to the cause.

Again, please don't take this the wrong way. I tell you this in the hope that it will improve your relationship with any electricians you hire, by enhancing their respect for you.

Now, back to your problem. There are lots of unanswered questions here.

Did this start recently, or has it been a problem for some time? If recently, can you associate it with any changes in your house or your neighborhood?

You say that multiple branch circuits are involved. How many?

Do all lights on all circuits flicker all at the same time, or is each circuit doing its own thing?

How old is your house?

Is any part of it wired with knob and tube?

Do you have any large appliances that cycle on and off while unattended, such as water pump, septic aerator, sump pump, water conditioner or purifier, basement freezer or refrigerator, etc.?

    Bookmark   July 23, 2006 at 1:39PM
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I know this is an old post but it just caught my eye. Some computer printers cause lights to flicker after they have been used. Samsung ML1710 is known to do this until it goes into power-save mode.

    Bookmark   March 16, 2007 at 8:15PM
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I agree check the branch circuit connections in the boxes for them. You have already moved the circuits around in your panel. If your house was built in the early 70,s I would say you had the common aluminum wire hot or loose connections and would have to do all your connections over or what is happening in Ontario having to replace your wiring to get house insurance. So check at the lights that are flickering for loose connections.

    Bookmark   March 23, 2007 at 7:26PM
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