Power flicker

[alex grams]

This may not be specific to workshops, but most of our resident electrical egg heads tend to visit this forum, so I thought I would seek some advice:

I have random power flickers in my house that I am trying to determine the cause for. Here is what I know so far:

-I Believe it is isolated to 1 circuit
-does not flip any breakers when it happens
-I do not notice any major appliances or consumers coming on or cycling whenever it happens. It has happened when it is cold outside, when it is hot, but no discernible pattern to it.

Could this be from a circuit breaker in the main box going bad? Other thoughts/causes? I would think a short in the wiring of the circuit somewhere would cause the breaker to flip.

Thanks in advance.

[Dave Gaul]

Alex, I work for an electric utility company, and have worked in distribution troubleshooting when I first started with my company. Sounds to me like a loose connection on one or more circuits in your breaker/load panel. It could be the breaker going bad too, but most likely it's a loose connection to the breaker, or the breaker is not making good connection to the bus bar on the panel.
If your whole house is flickering, chances are it's a loose connection in your meter panel.
You are correct about a short... this would or should cause a breaker to trip. This is a common problem when breakers and/or panels start to age, sometimes from corrosion, sometimes connections just loosen over time.
If you are not comfortable with electricity, please call a qualified electrician.
HTH.

[David G Baker]

Alex,
I had a similar problem a few years ago. I checked all of my circuits, tightened the screws holding the wires in my breakers but nothing cured my problem so I called my utility company. The technician did everything that I did but found no problem. He was getting ready to leave when he had a one more thing he thought he should check. He killed power at the pole, pulled the meter and checked the lugs that held the main wires in place and found that the main neutral wire was very loose. He tightened it and my problem went away.
There is a heat detecting tool that we used at work that would show up any heat in an electric panel or receptacle that may have a short in it. It was amazing how many panels had images of heat showing up on the small screen.

[alex grams]

Thanks for the info.

The frustrating part of my house is that the outlet mapping from the main breaker is non existent. I need to spend a few hours with a circuit tracer mapping out the house

Oddly enough, I have done a lot of electrical work on the house, but minimal work on this particular circuit.

Dave, fortunately I am comfortable with doing wiring in the house, so i will see what I can figure out this weekend.

[Aaron Wingert]

The only thing that will cause your breaker to trip is overload, as it is the breaker's job to protect the wire. If there is a short or an arc occurring (loose connection, abraded wire, etc.) the breaker will not trip unless that short pulls more juice than the breaker is rated for. That's how fires start.

Henceforth, the code now requres arc fault breakers (AFCI) in many circuits throughout the home. They will not only protect the wire from overload, they look for current jumping off the wire at a loose connection or damaged portion and trip accordingly.

Replacing the breaker is a good start, is very inexpensive ($3-$10'ish), and is one of the first places to look. However, I'd pay particular attention to the connections throughout the branch circuit as well. One loose terminal or wire connection on a light switch, fixture, receptacle or junction anywhere in the branch circuit could cause the flickering. The flickering you're seeing in your lights is very possibly indicative of electrical arcing and should be treated as an immediate issue and not as a nuisance that you'll eventually fix.

[Josiah Bartlett]

Every time I've had a power flicker that I fixed, it has been the neutral wire of that circuit that has gotten loose. If you have a decent AC volt meter, probe the voltage between the hot lead and the ground pin on an outlet while turning a load on and off (a couple of 100W light bulbs or a space heater work well for this). Now do the neutral to ground on the same outlet. First do it with the load connected to the same outlet as the meter, then do it with other outlets. If the voltage difference between the neutral and the ground changes or rises to more than 10 volts or so, you have a problem with the neutral and a safety hazard. If it just fluctuates on the hot side, the neutral is probably fine.

The neutral or hot may not be bad at the panel, it may be bad in one of the outlet boxes where the wiring is daisy chained. I had a couple of circuits like this in my house and re-stripping the wire and using good quality wire nuts has fixed the problem. When I build stuff new I like to use crimp connectors and pigtails to the outlets instead of wire nuts and daisy chain, its less likely to get broken if somebody replaces the outlet and doesn't pay attention to how the wiring is put back in the box.