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Voltage fluctuations

2K views 17 replies 7 participants last post by  frenchelectrican 
#1 ·
Just got the power turned on at a house we just bought (was off for 3 years). When running our 10 amp sawzall and little radio (nothing else) for a few minutes the radio kicks off and will not power on anymore. The sawzall seemed like it was cutting out for like 1/2 sec periods and then returning to normal. Went to outlet and put voltmeter on it and it registered 124 volts (no load). When sawzall was running it usually stayed at 123 volts but sporadically would drop to as low as 70 volts. Called POCO and they said it was fixed the next day. Went back to outlet and ran sawzall with voltmeter attached and it usually stayed at 124 volts again, BUT this time sporadically the voltmeter would jump into the hundreds (200 - 300+) for like a millisecond and come back down to 124 volts again. The sawzall usually didn't run faster during this "spikes" except for 1 time the motor speed up for a second.

Called the POCO again and requested a data recorder for meter (which they did). Any idea on what can be causing this? Bad transformer maybe?
 
#5 ·
Panel was just inspected as POCO required it since it was more than 12 months since disconnect.

I checked all connections in panel as well and they were all tight. Panel is only 3 years old (was replaced right before prior homeowner was foreclosed on).

I did not physically check lugs in meter pan though but they appeared to be tightened down as seen through meter cover (before POCO set meter).

Only 1 receptacle live in panel right now which I just put in and everything is tight in panel and at receptacle (is not back stabbed).
 
#9 ·
The most likely cause of increasing voltage is a bad neutral !
It could be in your instalation ?
Or it could also be in poco's gear.
Check all your neutrals,
if all is ok, call poco and ask them to check there's.

This is a serious situation !
You could get your equipment blown up.
240v on a 120v system is a disaster.
 
#10 ·
Since I checked all my neutrals already, I must assume it is on the POCO side. They are aware of it already, so hopefully the data recorder will pick it up so something can be done about it.

I guess I am still wondering, is it "normal" to have millisecond surges in voltage that are quick enough to register briefly on a voltmeter, but do not last long enough to speed up a motor in sawzall for example?

There was only 1 instance where the sawzall speed up for like a 1/2 sec, all the other times it didn't.
 
#11 ·
Since I checked all my neutrals already, I must assume it is on the POCO side. They are aware of it already, so hopefully the data recorder will pick it up so something can be done about it.

I guess I am still wondering, is it "normal" to have millisecond surges in voltage that are quick enough to register briefly on a voltmeter, but do not last long enough to speed up a motor in sawzall for example?

There was only 1 instance where the sawzall speed up for like a 1/2 sec, all the other times it didn't.
I know what you mean... it's like you're loosing your service neutral for a split second.... can't think of that circumstance.

Could it be transformer related.... I know absolutely nothing about that... you're new there.... could any of your neighbors (same transformer) be having those millisecd occurances.?
 
#17 ·
Well, we ran the sawzall for a few hours today and didn't experience any issues with it speeding up at all. I checked it with the voltmeter at beginning of day and it again stayed around 124-125 volts and all the sudden the meter jumped to 700+ for a split second and then came back down. The motor did not speed up during this "spike" so who knows what the deal is.... Maybe my voltmeter is going crazy....
 
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