ECN Forum Forums General Topics of the Trade General Discussion Area Interesting Question

Here's an interesting question posed to me recently by a freind that started getting over-sized electric bills. I actually witnessed the described symptoms myself, but couldn't come up with an answer for her off hand:

Situation: Pretty old housing tract, built in maybe late 50s or early 60s. Next door neighbor installs an AC unit in their house and suddenly the friends electric bills start to go up.

Symptom 1: When the neighbor's AC kicks on, friends lights dim.

Symptom 2: When the neighbor's AC kicks on, friends meter speeds up - visibly.

Now, the dimming lights is easily explained - undersized feeders, or perhaps feeders are degraded from the various effects of age (overheating, streching, oxidation, etc.).

However, how do we explain the meter speeding up? How could the extra current being drawn from the x-fer possibly affect a down-stream meter? And, inturn, how could the neighbors added load be causing the friends bill to climb?

Any enlightenment on this subject will be greatly appreciated. Thanks...

The only thing I can think of right off is maybe the neighbor (or whoever lived there before) is stealing power. Of course, the easiest way to see this is wait for the neighbor to turn on the AC, trip your friend's main, and see if the AC turns off. (assuming it's stolen after the main)

The only other thing I can think is maybe harmonics, or the neighbor has no neutral or an undersized neutral, causing one hot to go over voltage, and since it is off the same pole, might cause one of your friend's hots to go high, causing in higher current draw. Of course, I'm not too sure about this.

When I was living in my old duplex, my neighbor was stealing power from me. The basement was divided, but I saw a wire from my panel go to his side to his AC (I did the same thing, trip my main, his AC went off. I connected his 120V cable to 240V and blew his AC, then I cut it back and sealed the hole. Maybe something similar is happening here, a wire "disappears" somewhere.

Very likely that you are paying for your neighbours power.

Do what is explained in previous post.

Isolate and chop off unaccounted circuits.

Also check thet you are not paying for his hotwater heating if electrical.

Your meter will measure what current is going through it and will allowe for voltage inctreases and decreases for accurate measurement.

could it be that one of you has lost your nuetral, and backfeeding through the shared water mains?

Good answers..but I'm kind of lazy...here's what I would do 1st ~ watch the other guy's meter...does it spin faster when AC kicks in?

Then I would check the friend's meter as described previously.

Is this and underground serive. if so their might be a mixup on utility end. He pays for yours, you pay for his.

Thanks for the input.

This is a small tract home with very little to account for the $400+ electric bills she's getting every month.

I did check for any sort of crossover or evidence of power theft, but couldn't find any. Unless they are pretty good - which they would have to be - at hiding a cable.

I'll try ande make it by in the next few days and let the forum know what else I may uncover.

Thanks for your help gentlemen!

How does the specific electric meter work? If the lights dim then there's a reduced voltage to your friend's house. If your friend's load stays the same then the current must increase. Maybe the meter is current sensitive, not power conscious.