Someone I know has a strange electrical problem. As they turn appliances (microwave and air conditioner) on, their room lights get brighter, and at times, their computer UPS kicks on or starts beeping. Sounds like they are getting voltage spikes. What would cause this?
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I am NOT an electrician. I googled your Q and came up with this link:
http://www.precorp.coop/Docs/Misc/Power%20Quality%20Narrative.pdf
It appears that it may be grounding related. I'm sure that others will be able to give you a more definitive answer.
"A friend," eh? Don't wanna confess??
This is a classical symptom of a bad neutral connection somewhere between the power pole and the breaker panel.
Since this can be a quite hazardous situation they should have it investigated ASAP. First call the power company and whisper "bad neutral" to the repair folks -- that'll usually bring them running. If they don't find anything then have an electrician check it out.
Generally the fix is cheap -- just tightening connections. But leaving it unfixed can cause equipment damage, fire, or electrocution.
Edited 7/5/2007 11:43 am by DanH
Thanks for the responses.
OK, so how about the opposite? This summer, when my central air kicks on, the lights dim for a moment. This happens probably 8 or 10 times, 5-10 seconds apart, when the AC first starts. It's a pretty new furnace and AC unit, installed in the spring of 2004. This is the first year I've had this lights dimming issue. Any ideas why this might have started?
The lights dim multiple times while the AC is running? Or the AC has to attempt starting several times?Some light dimming for maybe half a second when large motor loads come on isn't unusual. In addition, at certain times of the day (early morning here) you may notice the lights flickering a lot due to line voltage variations as substations adjust their voltage to the rapidly changing loads.But if you're getting dimming after the AC is running, and it comes and goes several times, it suggests that you have a bad connection -- similar to the bad neutral, but on one of the "hots".And of course if the AC has to attempt starting several times then it needs service.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Lights dim because of voltage drop. An air conditioner needs quite a bit of power to get started ... many times what is required to actually operate. What this means, especially if you are using wires that are also used by other appliances, is that for that split second, the wire is way to small. Sort of the electrical equivalent of flushing the toilet while someone is in the shower. You avoid this by, first of all, measuring your incoming voltage. If you're already on the low side, it's time for a chat with the PoCo.
Then you run a dedicated circuit for the a/c ... using BIG wire. #10 for a 20 amp circuit, #8 for a 30, etc. Yes, this is more than the 'code minimum.' Then again, the code couldn't care less about your flickering lights.
It sounds like there is an open / bad neutral connection.
THIS IS A CRITICAL ITEM ... Call an electrician, and get it fixed NOW. Until then, UNPLUG everything on the affected circuits.
Ignore me, and things will fry. Surge suppressors will trip. A fire might even result. GFI's will no longer operate as GFI's.
must be important..you said it twice 8^)
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, wer ist jetzt der Idiot ?
Thanks ... I deleted the duplicate ... the first one seemed to get lost in the internet!