Electrical Q - Lights Flickering.

[430752]

Since I moved into my "new" home 9 months ago - built in the late 20's - the lights have been flickering to some degree or another. Not on/off flickering, but lights dimming a little and then returning, very, very quickly (like they're almost vibrating?) It seems to vary from one day to the next or one time to another, but really hard to tell. Me thinks instead it might just be worse at night when we rely on and notice the lights more. Pretty much all over the house, but never took time to study each light everywhere.

Recently I've been doing some electrical work around the house and noticed, for the most part, the electrical system is in good shape. I've only been working on two circuits, but noticed those and others in the vicinity are properly wired, tight fittings, not unusual splices, little or no disturbance over the years, etc. Built in the late 20's, it is BX cable with the old woven cloth jacket, bakelite insulation, and nickle-tinned copper wires. 12 or 14 gauge. Main box was replaced in the late 80's or early 90's and looks to have been done profesionally.

So, having done some work now, I can't find any obvious cuases for the problem. By the way, the flickering I do notice isn't on the two circuits I've been working on. (e.g., I'm working on a bedroom and upper hallway, the flickering is in a couple bathrooms, dining room light, master bed light, kitchen light, etc.) More importantly, in the back of my head I recall reading here some time ago that flickering lights were the sign of a real problem with electrical system.

So, should I be worred? And, where to look for a problem?

[Uncle Cracker]

Lights flickering can't really be a good thing, so I might be concerned. It may be the fixtures if they are period units, but if they're new, I'd look at the fuse box or the wiring. When one light flickers, do others do it the same way at the same time? That might be a clue. If it happens when a large load goes on or off, that might be another clue. If the neighbors have the same problem, then it might be a power company issue.

[pelligrini]

It could be the service cable. If you have 220 service and one of the legs has a bad connection it won't affect the circuits on the other leg. That's only if all the lights on that leg are flickering.

I rented a 20's house for a few years that had the same kind of wiring. The service was only 110 as well. At one point all the lights were flickering and it ended up being a bad connection in the service drop from the pole. When I was a kid, half the lights in the house and the dryer, oven and AC wouldn't work. It ended up being a corroded connection in one of the legs of a buried service cable.

[dbhost]

Well, it doesn't look like you are anywhere near Huntsville Texas so it's not the state bringing Old Sparky out of retirement...

[LarryG]

It's possible that Dave (dbhost), writing in jest, nailed the problem. Try to determine whether the flickering occurs when some kind of heavy load is kicking on, and see if that load is fed from the same leg of the panel as the lights that are flickering.

Ideally the two legs of the panel should be feeding as close to half of the total load at any given time. If one leg is carrying more load than it should, or is close to being maxed out, the start-up draw of something like an A/C unit motor could be temporarily "starving" the other circuits on that same leg. If this is, in fact, the situation, the solution could be as simple as moving one or more breakers to the other leg, to better balance the load.

[RAFlorida]

What other posters have stated, +1.

But, if you have access to an analog volt meter where you can test your main breaker, and watch to see if there's a movement when the lights flicker. If there's movement, then you may have a connection problem from the breaker up to the transformer.

[430752]

thanks. The service is 200 amp, 3 wire. It very well could be the service line from the pole since I've notice the weatherhead appears in less than optimal condition. Actually, nothing wrong with the head itself, but some separation from the house. Which I've been meaning to address (through an electrican, not myself)....... already added to the list. I didn't think it mattered much, but might be a cause.

I'll pay more attention to the flickering, but pretty sure not due to any load. I say this because I always notice the flickering in the bathroom, for example, before I go to bed and am brushing my teeth. At Midnight, more or less, there is no washer, dryer, dishwasher, a/c, etc. anything else operating. House is gas fired hot water radiators (but an elec circulation pump, yes), gas hw heater, no central air, all window a/c units are out for the winter. gas stove top. yes, elec. oven, but off at that time of night, etc., etc.

[430752]

But, if you have access to an analog volt meter where you can test your main breaker, and watch to see if there's a movement when the lights flicker. If there's movement, then you may have a connection problem from the breaker up to the transformer.

Standard multi-meter? set to volts? amps? And where to measure? Across the two live legs of the main power line? Hope not. Can it even handle such a load (200amp)?

[Hellrazor]

My guess is a problem with the neutral or a bad service connection.

[BobSch]

Standard multi-meter? set to volts? amps? And where to measure? Across the two live legs of the main power line? Hope not. Can it even handle such a load (200amp)?

Set to AC Volts from one hot side to ground. Also if you can identify that all the flashers are on one breaker, it may be a loose or defective breaker.

Don't worry about the 200 amps, since you'll be measuring voltage and not current. That's why you want to make sure the meter is set to AC Volts, NOT Amps or resistance (Ohms). If you mistakenly set it for Amps, you'll effectively put a short across the line and (If you're lucky) blow the fuse in the meter, otherwise you'll let all the magic smoke out of the meter DAHIKT

BTW, If your meter has different voltage settings, make sure you select at least 200 volts.

[Hellrazor]

Standard multi-meter? set to volts? amps? And where to measure? Across the two live legs of the main power line? Hope not. Can it even handle such a load (200amp)?

How much experience do you have "playing" with electric? Ignore my reply if you don't trust or have experience working in a panel.

On a 220/240 service - set the meter to volts.

On the lugs AND main breaker-
1. Check hot to hot
2. Check each hot to ground
3. Try to check each hot to ground with the lights are flickering. You can check hot to hot too.

[RAFlorida]

What Mike and Bob have posted is right on.

IF you feel unsure if you can do the above, then you may want to hire an electrician or someone who does electrical work, (a friend or relative). Please keep us posted on what's happenin'.

[Daryl]

My first house had flickering lights. By chance one evening I was near the fuse panel while the cloths dryer was running. I smelled something hot and opened up the box and the bakelite was pretty well burned up. The electrician said it was because of the aluminum lead in not being tight to the breakers. If you don't find the problem I think you should have a pro look at it. Loose connections can make a lot of heat.

[herb fellows]

My 2 cents, you start with simple, then go on from there. Unless I've missed it, you haven't said if you have figured out if all the flickerers (is that a word?!) are on the same circuit.
If you can determine that they are, you narrow your problem down a lot, so that's the first thing I would figure out before doing serious electrical stuff.

[L. D. Jeffries]

+1 pelligarini's answer. Had the same problem in my shop which is 50' from the feed from house box. Buried 200amp cable to box in shop. Ran under a cement block retaining wall.
On advise from electrical friend dug under wall and sure enough there was corrision from cement one leg nearly gone. Spliced a new section in a plastic pipe. No problems with flickering light again! Cable WAS underground type!