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Dimming Light, etc.

Posted by stanwv (My Page) on
Tue, May 4, 10 at 16:03

We have a vacation cabin that just started having this problem. Some lights will go dim and the ceiling fan will buzz occasionally. There's no rhyme or reason as to when this happens, but when it does it cycles several times then will go back to normal. It seems to happen when the refrig or well pump kicked on, but not always. Sometimes some lights will go completely out a brief moment while others stay on. I looked at the breaker panel thinking they might be circuits all on one side, but it happens to circuits on boths sides at the same time while others are okay. What is going on and could it be on the power company's equipment?


Follow-Up Postings:

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RE: Dimming Light, etc.

Circuits alternate top to bottom and side to side. You can have circuits on either side that are on the same leg.


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RE: Dimming Light, etc.

I'd look for a loose feeder connection in or ahead of that panel. You'll know it when you see it because it will most likely look like it's been hot, as in temperature hot.

This may be a hazardous situation. If you're not qualified to tackle it, call in a pro right away.


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RE: Dimming Light, etc.

I'd also suggest you check the connections at the breakers and make sure they are good and tight. That will also cause the symptoms you describe.


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RE: Dimming Light, etc.

One of the hot lines has a loose connection. This could be anywhere from the POCO transformer to the main breaker inthe panel,including the weather head connection, the meter pan connections, the main breaker connections.


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RE: Dimming Light, etc.

Thanks for the replies. We had an electrician and the builder come in and check out the internal wiring. They said everything looks okay on our end. They believe it is probably an open neutral somewhere on the power company side. Another electrician we know suggested the same thing by what we described. We reported it to the utility. This is a rural coop and we've been told that it may be a while before they can check out their side. We are the only camp on that transformer.


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RE: Dimming Light, etc.

"Some lights will go dim and the ceiling fan will buzz occasionally."

This sounds far more like a loose hot than a neutral.

A loose neutral causes brightening of sme bulbs and dimming of others.
The brightening is the big indicator of a loose neutral connection.

A loose neutral is very dangerous since the 120 V can approach 240 V and fry anything plugged in.

Straight 240 V loads are not affected by a loose neutral (they do not even use the neutral).

A 240 V load would be affected by a loose hot, and switching of 240 V loads will cause some funny things with a loose hot.


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RE: Dimming Light, etc.

"A loose neutral is very dangerous since the 120 V can approach 240 V and fry anything plugged in.

Straight 240 V loads are not affected by a loose neutral (they do not even use the neutral).

A 240 V load would be affected by a loose hot, and switching of 240 V loads will cause some funny things with a loose hot."

Yeah, I read up on that. The website I visited suggested that the majority of the time, an open neutral is on the power company equipment. I tried jumping on the floor to shake the building hoping to induce the problem thinking it was a loose connection inside, but nothing happened. It did seem to coincide with the refrig kicking on or the well pump which points to an open neutral from what I read. Funny thing is it doesn't do it everytime and was more likely to occur in the evening or morning. Some lights will go dim or briefly go out for a second. The flouresent lights didn't seem to be affected by it.


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RE: Dimming Light, etc.

"It did seem to coincide with the refrig kicking on or the well pump which points to an open neutral from what I read."

It would be pretty rare to have a lose neutral without any lights getting brighter., but not impossible if no lights are on one leg of the power.

Well pumps are almost always 240 V loads and would have no effect (and see no effect) from a loose neutral.

A 120 V refrigerator would see the loose neutral if it was in the circuit.

A loose neutral is an emergancy.
Any 120 V load can be damaged if it is on the higher side of a loose neutral.

Instead of being 120/240 V the mid point can shift depending on the loads on each leg.

You could have 80/160/240 V.
If the loading on the legs is very unbalanced the high side can approach 240 V.


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RE: Dimming Light, etc.

Power company said they found a burnt wire and repaired it. No information other than that from them. We'll have to wait until someone goes up there to see if that fixed it. If it was a hot wire, wouldn't an entire leg be dead? So, it must of been the neutral wire?


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RE: Dimming Light, etc.

" If it was a hot wire, wouldn't an entire leg be dead? So, it must of been the neutral wire?"

It depends on what a "hot wire" is.

Most likely a loose connection resulting in arcing that generated heat.

The insulation on the wire will be damaged, as well as pitting and damage to the surfaces that are supposed to be tight from the repeated arcing.


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