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I have several reasons to believe somebody is stealing my power. I decided to flip all the breakers... and behold my next door neighbor's exterior garage light turns off then comes back on but significantly dimmer. Now since I can't see the front from the back of my house where the breaker is, I had a friend help me have eyes in both places by posting up front or flipping the breaker and vice versa. We both saw this light do the exact same thing.

The questionable part about it is that it only behaves this way concurrently to my breaker when this light is super bright, white. It doesn't even flicker when dimmed low yellow. It is NOT a motion light, and before all of this I never paid enough attention to know if the fluctuation in brightness is abnormal but I want to say I thought it was usually if not always very bright.

Now maybe we tipped the neighbor... but the last time we attempted this experiment, the light literally flipped itself off and went to dim seconds before we could turn the breaker. Then it stayed dim as far as I know for the rest of that night. The very next day the power company cut my line because I haven't paid up the nearly $2,000 due now. (2 months usage with only 2 people).

My property consists of two detached houses on the same lot, separate addresses and same meter. I purchased 2 years ago, live in one, rent the other... I evicted the tenants in the front house because they couldn't pay for all of the energy I thought they were using. Then my first bill without them was more than double and has been nothing but random since.

I don't want to start a problem with my neighbor unnecessarily. How can I determine if the power usage is due to my neighbor?

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    So the neighbor you're referring to is not the detached house on the same lot? If so, does your house have any common walls with your neighbor? Are there any cables running across between your house and your neighbors? It might be worth your while to pay an electrician to spend an hour or so poking around to see if he can find anything suspicious before getting the law involved ... – brhans Jun 22 '17 at 18:39
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    Either the garage light is a motion-activated light with dual brightness, or something is very wrong about your wiring. In any case, we can't say from here. You should have an electrician look at it. – isherwood Jun 22 '17 at 18:39
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    Not saying they aren't stealing, but you flipping the breaker on/off repeatedly might be causing a phase imbalance on your shared transformer, affecting their light bulb. I'd be more suspect of a possibly faulty meter to be honest. – CactusCake Jun 22 '17 at 18:42
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    Did you carefully go through the now empty rental house to be sure your former tenants didn't intentionally leave high electrical loads turned on? – Mark Jun 22 '17 at 22:37
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    Aside from getting this sorted out, you need a meter on the rental house so you don't go around evicting tenants for no good reason. – Ecnerwal Jun 24 '17 at 1:05
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You have a tough bit of detective work to do, but it should be possible. The good news is a very large load is likely to be a continuous load, so it shouldn't be too hard to catch.

First check for weird outside wires.

The usual drill with pot growers is to bury Romex (NM) cable just enough to conceal it. This shabby workmanship is usually fairly easy to spot. Proper underground cable is at least 12" deep, rigid conduit can be 6" but that's because you won't damage it with a shovel.

A sneaky cable would explain all this even if they took away their grow lights. (you have inspected the unit, yes?) Imagine they were stealing power from the neighbor, then also stole it from you but hooked it up backwards. It would be a dead short, limited by the long wire run, and that might be enough to not trip the breaker.

OK, no luck?

Next, get educated.

I know some people don't like learning and don't want to be seen as smart. But frankly, the alternative is pretty expensive. Upside, this is a big enough deal you can afford a few toys to make learning easier.

  • Learn how pressure (volts), current (amps), power (watts and VA) and energy (watt-hours and kilowatt hours) all relate to each other, because you'll be using them a lot.
  • You need to be able to multiply and divide. It doesn't get any harder than that.
  • Get a book on wiring a house and read it through. There are a few things you can skip but the main thing is you need to be comfortable working around wires and inside panels.
  • Figure out how to get instantaneous kilowatts out of your electric meter. (smart meters should cycle to display it, old meters are trickier.)
  • Toy: a $20 "Kill-a-Watt" meter which will let you measure most of your 120V loads.
  • Toy: A $100 clamp ammeter which lets you clamp around a single "hot" wire and see what current it is drawing.
  • Toy: A "whole-house power monitor" which wires into your panel and analyzes your power consumption. It shows you exactly which appliance uses how much power, and give you a very complete picture of your power usage. These are in the $300-500 range and permanently install two clamp ammeters in your service panel.

Once you are able to easily read your instantaneous watts (e.g. at the meter), you can try flipping off one breaker at a time and try to narrow it down to one breaker. If your two units have separate panels but are fed off one meter, you may be able to use a clamp ammeter to measure both main hots (one at a time) to see which house is the source of it.

If an answer doesn't become obvious at this point, you'll need a more methodical approach.

Map your circuits

This is tedious but very useful to know. You know about all your hardwired loads (lights, oven etc.), get some dollar store night lights for testing receptacles. Shut off one breaker at a time and see what got turned off. Mark the service panel with what things that breaker controls, and mark each device, switch or outlet with the breaker number.

Next, use the Kill-a-Watt to measure the actual power draw of everything that plugs into a receptacle. I have been known to measure fixed loads also, by opening up the box and using a stinger extension cord. You cannot measure 240V loads with a Kill-a-Watt, but then you don't have to - 240V loads have nameplate labels which state their power usage. You just have to figure how often (percentage of time) the big load is on. By now you should have a notebook or excel of each of the circuits and the Kill-a-Watt power usage of each of the devices on that circuit.

Look for anomalies

Now put the clamp ammeter on each of the "hots" coming out of a breaker. Compare that to the Kill-a-Watt data from your known loads on that circuit. It can help to just turn those off while you're measuring. The goal is to account for all the power exiting every breaker.

For 240V loads, measure both hots separately. A significant difference in amps should raise alarm bells. Dryers have been known to be unequal, turn the dryer off and see if it all goes to zero.

The goal is to narrow the unexplained draw to a single circuit, then tear into the circuit to find exactly where the draw is. You can follow the circuit down the chain of receptacles and put the clamp ammeter on the hot wire in each receptacle until you find the leakage.

Be prepared for the possibility that it isn't any sort of theft, but something left on (heater in vacant apartment?) or just appliances that take a lot more power than you thought (air conditioning).

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Look at the neighbor's house tonight to see if the lights are on. Since the power company cut off your power, then the neighbor's lights will be off if they are using your power. It has to be a lot more than just the garage light to run up the kind of bills you're describing.

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I can think of a few things to try to identify this.

That someone used to grow weed, and got rid of the meter makes it all sound a bit fishy. For example, it's possible the previous owner was actually stealing power from your neighbour, and now the connection is working against you.

I've never dealt with a cross connection after-the-meter, so I'm not sure exactly what would happen, but Ohm's law dictates that current (which you pay for) is inversely proportional to resistance, so a cross connection is going to cause some amount of current to flow.

Audit cables

Go around your property (both houses) and find any cables that are running into the ground. Ensure you know what they are and where they are going. At a minimum there's a connection between your two houses, so be sure you can identify that.

Use a non-contact voltage sensor to verify which breaker powers which cable.

Normally there would not be any cables penetrating your foundation below ground-level, but of course if there was power theft happening, anything is possible. If you have a finished basement it will be harder to find this, but you may still notice ground outside that looks more recently disturbed, or something else that can tip you off to the possibility.

Check for power feeding back

The fact the other light is on but dim when you turn all your breakers off is kind of strange, but it could indicate a cross-connection. If this is happening then when you turn all your breakers off (both houses) there should still be power on some circuit(s).

Again, use your non-contact voltage meter to find these and a multi-meter to verify. A non-contact meter can pick up induced voltages (hence need to verify) but if you have all breakers turned off, normally you wouldn't get any induced voltages.

Check from the neighbor's place

Sounds like you might have an adversarial relationship with the neighbor, but one thing to check if you could is to get them to turn off all power, then see if anything stays powered up.

If they are deliberately stealing from you, they may disconnect it or more likely not allow you to test this way, but might be worth a shot.

Get a cable locator

You can get a cable locator to come out and find and mark any underground cables. In many jurisdictions this is a free service ("Call before you dig").

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One way you can check this is to turn everything off in your house, you can flip all the breakers but if you keep doing that you may tip off the neighbors. Some things will still draw electricity if they are plugged in but turned off so those will need to be unplugged. You'd probably want to shut the breaker for the electric water heater and furnace. Now check your electric meter, it should show no usage. If the meter shows no usage then you should try this exercise several times a day because if the neighbors are stealing then it may be something that runs intermittently like an air conditioner. If it does show usage start flipping breakers off until there is no usage. When you find the breaker that shows usage double check everything on that circuit to make sure there's nothing on. If there's nothing on and your still showing usage then there's a problem and you should call an electrician to figure it out. You didn't say how big the house is or what the rates are where you live but if you're averaging $1,000/month then you have something wrong.

protected by ThreePhaseEel Jun 16 '18 at 6:50

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