I was at my brother-in-laws for din

[DonLeffingwellPE]

I was at my brother-in-laws for dinner Sunday night and he told me of a problem he had been having with his lights. He said they keep flickering, sometimes fast, sometimes slow. It doesn't happen all the time, and it seems to be random. And it only happens in part of the house. While I was there, his father and I looked at the service panel. It as a 100 amp-service. The cover was off so I didn't get the make. Both feeds came into the right side top of the panel. His father is a retired electrician. He told me that he had replaced many of the breakers the year before because they were rusty. (??) While we were there that night, he tightened all the connections. I myself pulled on all of the hot wires, to make sure none were loose. We shook our heads and went upstairs. While we were sitting down, sure enough, the lights dimmed and then got very bright. Then they would flicker, and then it just stopped. There has been a lot of new housing in this area.

My own feeling is that the service transformer on the power company side of the system may have some insulation failures in the windings or moisture problems, or both. The local utility doesn't want to be bothered. (I believe the feed to this house is overhead to a weather cap, and then down a conduit).

Any ideas?

Don Leffingwell
dleffingwell@snet.net

 

[jbartos]

Suggestion: This problem may be monitored by:
1. Oscilloscopes
2. Voltmeters
3. Voltage recorders
4. Etc.
at your service entrance panel. However, it may also be inspected by the Utility or Licensed Electrical Contractor.

 

[Dan76]

Does the dimming/flickering occur in the same part of the house all of the time or different parts? If its only in a few of the same rooms all of the time find out what else is on the circuit supplying those lights, a cycling load like heaters, A/C or a refrigerator could cause a voltge transient when it starts and shuts down. Solution put the large load on its own circuit breaker.

Are the lights Incandescent or Flourescent? If they are flouro's try changing the starter and ballast.

If it turns out to be the local utility, and they dont want to check out the problem try calling your local utilities commission, you may also ask the neighbors if they are experiencing similar problems.

Good luck, -Dan76

 

[smcbride]

You said you checked the "hots" remember the neutrals or grounds are just as important. If it is the feed to the house, everything in the house will dim at the same time, it did not sound like that is the case from the information given. It is more probable that there is a poor conection in a j-box between the panel and lights that flicker. These connections are ususally made with wire nuts, and nut has losened over the years, or the wire breaks do to the stress of the nut and arcs. Try to trace the circuit from the panel to the light and check the connections. The Electrician Father might have an inductive tone generator that will aid in tracing the circuit, but you need to disconnect from the panel. Another possibility could be the panel itself, the rusty breakers are an indication that water has been getting into the panel. It is common to have water follow the service wire into the house and into the panel, so the branch breakers may not be on thing needed to be relaced, you may need to inspect the service breaker, or fuses and the buss bars for damage too.

 

[rlaft]

To emphacize what smcbride is saying, I would be willing to bet that the problem will be found with the neutral side of the circuit. Look at the connection bar for all of the neutrals and the bare grounds. Check the tightness of those connections. When the lights are flickering, measure the voltage between that bar and a known ground that is independent of the power panel. Maybe a water line or simply a stiff wire or rod poked into dampened earth nearby.

 

[ControlMan]

Don:
Lots of good ideas have been mentioned. Several items need to be nailed down, however.

(1) System Ground - is the main panel grounded according to Code requirements? There should be a ground rod (with rare exceptions) driven eight feet into the ground with a preferably solid bare copper wire properly attatched leading into either your meter box or your main panel. It should be firmly attached to the ground bar on either panel. You can tell which is a ground bar by determining whether or not it has a direct metal-to-metal connection (proper term: is bonded to) the metal panel box itself. This can be a screw or a metal jumper, etc. There should also be a similar bare wire copper bond to the cold water piping in the house if the piping is predominantly metal.

(2) Bonded Neutral - this is trickier to describe in generalities. At some point, probably in your panel, your main neutral bus will be bonded to your ground bus. This is very important. There is also an important neutral grounding/bonding procedure which must occur at the transformer on the pole. It can and does happen that these connections fail over time, and it is not unreasonable for you to insist that your utility company come out and thoroughly check the transformer, its outputs, and all its connections thoroughly, even to the point of putting recording meters on the transformers for a time. If they refuse to do this, do not hesitate to contact whatever regulatory board is responsible for their oversight.

(3) Main Bus/Breaker - your letter did not specifically mention how the main bus was fed. This area is my site of greatest suspicion, given that problems occur in some parts of the house and not others. If the panel is a simple bus, one side may have a defective/failing/degrading connector or connection where the main comes in. You would not be able to completely determine this simply by "wiggling" the wires. An infrared thermometer might detect this, or actual inspection behind the bus by disassembly after pulling the meter (licensed electrician needed here). If the panel is a main breaker type, again one side may be failing; here we go with the infrared thermometer and the disassembly, etc. But you see my point - if only one bus is momentarily shorting inside an old main breaker, you could get unusual high and low voltage-appearing symptoms in only portions of the house intermittently. I have seen several instances where old main breakers did not fail safe.

(4) Scary thought - in old systems, it can be combinations of the above - and more. The reason I say this is that some panels split the neutral bar as well, thus introducing the possibility, albeit remote, that one side has loosened. If your panel has a split neutral, check this as well.

By the way, a 100 amp service is woefully inadequate if your brother-in-law upgrades appliances, adds new ones, etc. If parts in the old panel had to be replaced because they were "rusty", LOSE this panel and upgrade to a 200 amp panel. I am betting your problems would vanish. If you are still worried about the state of the utility feed, insist on the recording meters on the utility side. Seriously, Don, you guys can spend a lot of time (and money) chasing these problems around on a creaky old panel. The real problem is that, in the meantime, if your brother-in-law has computers or other sensitive electronics at home he can screw these up big time before finally succumbing to the obvious and bringing his physical plant up to spec.

Hope this helps!

 

[DonLeffingwellPE]

Thank you to all who responded. We did get a licensed electrician to look at the panel. The problem was a corroded main breaker, which of course we couldn't see without taking the panel apart.

Don