Lights flicker?

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  #1  
Old 09-20-07, 05:34 PM
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Lights flicker?

When the washing machine or sometimes other big appliances start there is a quick dim, then back to normal. During the running of the washer the light flickers.

Now we're supposed to be getting a wiring/panel upgrade in the next little while but I'm wondering what causes this.

Thanks!
 
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  #2  
Old 09-20-07, 10:10 PM
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This is usually caused by a motor spin-up or similar effect. When it first turns on, your A/C, washer, etc. can draw more than the amperage they normally will when running.

Great example is the 50amp AC that pulls even more at startup (without tripping the breaker - it's designed to do this). Once it's spun up to normal operation, the amps drop back down.

In a 100-amp box, gosh, you start butting right up on that 100 pretty quick if you're sending 50+ to the A/C when it kicks on. 60-amp service would put even more pain on the system. I'm guessing you have one of those two sizes right now?

BTW, when you say wiring/panel upgrade, are you upgrading service, or just replacing the panel, for example, to get rid of a Federal Pacific or something like that? I ask because in some localities, you can panel replace while staying at an older service (usually 100a). I really assume that any decent electrician would see your overload situation and make sure you were upgraded, though.
 
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Old 09-21-07, 08:20 AM
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A quick dimming of the lights is somewhat normal when a large appliance kicks on. There are several factors that can contribute to the dimming, but it is often just a nuisance which is not worth the cost of fixing. If you are having the service upgraded, the dimming effect will probably decrease with the larger service.

You could eliminate much of the dimming on the washer circuit by running a dedicated 20A circuit to the washer.
 
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Old 09-21-07, 03:56 PM
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Well our electrical amongst other stuff was inspected by a house inspector as we are doing other renovations too.

The electrical panel is currently a fuse panel, so it planned to be replaced by a 100amp 240 volt 32 breaker panel, and we're fixing a bunch of outlets, plates/switches and old wiring.

Regarding Federal Pacific, is there a real danger there? Our ac unit uses a FP stab-lok breaker (In the disconnect) that we just replaced this summer, as it stopped working.
 
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Old 09-21-07, 04:17 PM
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Fpe

Our "Northern" friends will chime in. My understanding is The Canadian versions were OK,

The USA versions... EEEEK!!!
 
  #6  
Old 09-21-07, 05:08 PM
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Dimming is pretty common when power is first applied to large loads and is particularly noticible when motors are involved. This is normal, and can be worse when there are heavy loads on the POCO supply, like evenings around the times folks start getting home from work.

Flickering lights are usually caused by loose connections or a condition that sets up a "not quite solid short" between some combination of line-to-line and/or line to neutral/ground. This is a condition that requires immediate inspection and repair as either condition can cause serious problems - up to and including damage to equipment, personal injury, and fires.

Federal Pacific breakers lost their UL listing because the tests used to verify the correct functioning of the breakers under certain conditions overload were rigged by FPE. Subsequent inspection found that many breakers would't trip under any condition of overload. There are many other well documented problems with both the panels and breakers as well. As to the Canadian versions, there was a recall back in the 90s because........the breakers wouldn't trip. Seems that some FPE breakers somehow got re-branded Federal Pioneer (the Canadian brand name) also. A good search using Federal Pacific will usually bring up the definitive information site for FPE issues.

If you only believe 5% of what you read on the web you still have a good case for replaceing any and all FPE breakers and panels.
 
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Old 09-21-07, 05:51 PM
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Flickering..

Originally Posted by Codyy View Post
When the washing machine or sometimes other big appliances start there is a quick dim, then back to normal. During the running of the washer the light flickers.

Now we're supposed to be getting a wiring/panel upgrade in the next little while but I'm wondering what causes this.

Thanks!

Thanks Unk, I'll look deeper. I have a friends garage (automotive, leased) I want to upgrade, but need some solid info for the landlord.

Now to the post:

(sorry we sometimes wonder)


The flickering, May be a simple case of imbalance on the loads. Ask when you upgrade for them to pay special attention to the equipment (balance).

It also could be bad/loose connections on either end.

This should be corrected Just with the upgrade.

Meaning no real intervention needed.

Mention it to the contractor so they are aware of it, and it should go away.
 
  #8  
Old 09-21-07, 05:52 PM
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If you're having an electrician come in to do the service change, you may want to have him look at the lights being affected. Putting lights on a circuit of their own (seperate from outlets) will usually take care of the dimming effect. You may notice some effects if you have major loads of another circuit on the same leg, but usually it's caused from loads on the same circuit. You should see if it's possible to rewire the affected lights (without racking up a huge bill).
 
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