AC Voltage (How high is too high?)

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Old 07-19-13, 03:03 AM
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AC Voltage (How high is too high?)

I have an AC voltage question. I know the "normal" (Under perfect conditions) is 120/240 VAC but how high is too high?
Right now my computers UPS system says 128V (My Auto-ranging DMM says 127.55) I live in an all electric apartment (Hot Water/Range/Heat/AC) - Which is on almost full blast (As full blast as two* small 5K ones can get)

I also tried turning on the range (Small 24" unit) and it only dropped by 1/2 a volt

I can't test the 240V at this time without unplugging the stove or removing the panel cover which is no-no for me as I don't feel comfortable doing that plus it is painted over.

*= I have two cheap 5000 BTU AC units in a 310 SQFT 1BR apartment both running at the same time on different breakers. The bedroom is separated from the living area by half a wall and no door.
 
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Old 07-19-13, 04:27 AM
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Nominal 240/120 service +/-10%. 216-264.
 
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Old 07-19-13, 05:35 AM
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OK so this was probably a stupid test (Being as hot as it is outside) but I briefly turned the heat (240 VAC Baseboard units) on and the voltage actually went up to 141VAC and then the UPS tripped out saying "AC Power too high using battery power"
but as soon as I turned off the heat it went back to the "Normal" 127VAC
 
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Old 07-19-13, 07:26 AM
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If the voltage drops on one leg while it rises on the other leg by the same amount, it is indicative of a loose neutral in the service or before the meter.
 
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Old 07-19-13, 07:48 AM
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Well I can't actually test the 240Vac (I remember this happened last year around the same time but the POCO said it was a loose hot wire that was burned up and they had to replace the meter can) but my problem just got worse. now Only half of the panel has 120V (It seems every other breaker is dead)when I turn on the stove/Heater the other parts come back but the stove does not heat and my water heater went cold
PS I am posting from a laptop now as the breaker my computer is on is one of the affected ones
Is there a way to fix this my self? as I can't afford an electrician/Poco visit. also there are 4 apartments in each building and my neighbors power is the same thing with half of the panel dead
I will wait until someone else calls then and hopefully has the problem fixed on their penny
 
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Old 07-19-13, 07:54 AM
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Call your landlord and ask him to call the power companies emergency number, you seem to have lost a leg to your service to the entire building affecting all the apartments. There is normally no charge for this service.
 
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Old 07-19-13, 08:07 AM
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Also keep the two pole breaker off until this is repaired.
 
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Old 07-19-13, 08:09 AM
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OK I called the landlord and apparently someone already called them and the POCO is enroute to my location I will let you know what they find
 
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Old 07-19-13, 09:53 AM
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OK all is fixed apparently a rodent got fried and also the neutral was really loose (Practically disconnected said the service tech)
 
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Old 07-19-13, 10:19 AM
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The loose neutral is entirely consistent with your observations, as PC boss noted earlier. Correcting that should restore normal operation.

Good catch and good call.

Can you let us know how it's doing in a couple of days?
 
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Old 07-19-13, 10:23 AM
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OK I will let you know in a couple of days how everything is

Also when they turned the power back the voltage is now at about 122-125VAC
and the 240 (Measured by the POCO tech) was 244-247VAC
 
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Old 07-19-13, 11:02 AM
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Boy, don't those new voltage values sound great? Good job this was caught and corrected as early as it was.

Thanks for the update. If you test again in a couple of days, that will let us all know the repair seems to be holding.
 
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Old 07-21-13, 10:43 PM
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Everything is still fine (Except from a total power outage caused by a failed transformer which is unrelated to my voltage problem)
The Voltage is around 121-125VAC
 
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Old 07-21-13, 10:58 PM
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Thanks for the update.

The Voltage is around 121-125VAC
Those numbers sound reassuring even from here. I'll bet you're enjoying seeing that.

Sorry about the outage.
 
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