dealing with overvolts

self ^ | 030/25/22 | self

[TexasGator]

“If your neutral connection to the transformer on the pole loses connection, your home appliances could find themselves being powered by voltages approaching 240 volts instead of 120 volts. “

Please explain how this happens.

[TexasGator]

“A sag or swell phase to phase will force battery operation then your load drops. Battery is dead and UPS turns off.”

He says his battery works fine when power is lost.

[eyedigress]

I’m not sure what turns off that UPS.

Input can swing +/- 10%.

Those little systems also have outputs that are not battery protected. They are labeled.

[eyedigress]

Sounds like a faulty UPS. I doubt an ability to log into it and read what is happening.

There might be some minimal info from the display if it has a display you can cycle through.

[William Tell]

"Please explain how this happens."

Most residences receive their power from a transformer on a nearby power pole. The output of that transformer is a center-tapped winding. Let's call the output wires "L1","L2", and "neutral" (the center-tap).

The voltage measured from L1 to neutral will be 120 volts. The voltage from L2 to neutral will be 120 volts. The voltage measured from L1 to L2 will be 240 volts.

If the homeowner has an appliance like a clothes dryer which takes a lot of power, the appliance will get its power by connecting between L1 and L2. This delivers the power required at lower current than if the power were delivered using L1 and neutral, for example.

Most home appliances only require 120 volts to operate. Usually the house is wired so that half the house is wired between L1 and neutral. The other half of the circuits are wired between L2 and neutral.

Imagine now that the homeowner has one 120 watt light bulb between L1 and neutral. Further imagine that the homeowner has ten 120 watt light bulbs each wired between L2 and neutral. The current flowing between L1 and neutral would be one amp. The current flowing between L2 and neutral would be ten amps.

If you then disconnect the neutral connection at the pole, the light bulb on L1 would be wired in series with the parallel group of ten light bulbs. The light bulb on L1 has a resistance of 1 ohm. The parallel group of bulbs on L2 has a combined resistance of one tenth of an ohm.

The voltage between L1 and L2 will be divided such that about 90 percent of the voltage, about 216 volts, will appear across the bulb connected to L1. The bulb would glow very brightly for a fraction of a second and then the filament would melt.

[samiam5]

My parents’ house had a similar issue. We checked, poked and prodded. Finally found the problem was a tree growing into the feed line between the transformer and the house.

[Bob434]

i wonder if that might be it as others in the area are having the same issue- and it began aroudn the same time- so that would seem to indicate something out at the line instead of inhouse- If the next electrician can’t find an issue, we’re gonna have to call the power company i guess-

[Gaffer]

First thing I always did when there were strange problems like voltage irregularities or possible current flowing between ground and the line connection was to check for a loose neutral in the panel.

[NonValueAdded]

Get rid of the curlyques, fire hazard

[Bob434]

Thanks, we are transitin8ng to led- they run much cooler. I bought some nightlight leds for,the dark house, and suppoxedly,supposedly, cost only like $2 apiece per year to run 24/7 (thry are on a dimmer switch controlled by daylight, so,during day they aren’t on except,in darkest parts of the house). They put off a lot of light too. The old regular bulbs for nightlight kept blowing out every few months, or so,etimes even when you unplugged them and. Plugged em back in. Thye were very sensitive.

These led ones have been going and going for a year now. And you can use higher watts for,enclosures that are susceptible to,overheating like bathroom fixtures where they usually,limit to 60 watts for regular bulbs