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Lost utility leg

3685 Views 13 Replies 11 Participants Last post by  chandler48
Hi all,

My dad lost one of the 120 legs to his house during a storm last week. He waited a few days hoping it would resolve itself (yes, I know). He finally called me and the power company is coming to check it out today.
I think the power was backfeeding through some of the double pole appliances, because many of the lights were dimly lit. The other half of the circuits seems unaffected.

My question is, what has probably been ruined by this low voltage? I know the fridge and microwave were receiving low voltage. The fan on the fridge was running when I got there but it obviously wasn’t cooling.... He also had several fluorescent lights, a sodium vapor yard light, and some photocell controlled landscape lights that were hit with low voltage.

Thankfully most of the electronics in the house were unplugged or on the other leg. Is everything else going to need replacing?
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There is a good chance that everything is OK. You won't know until the power comes back on.
Until it is repaired I would turn off all double pole breakers in the panel to prevent backfeeding.
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I'm not sure what 'backfeeding' is, as you put it, and I suppose in reference to 240v double-pole breakers? If a 'side' of the panel is lost, meaning that one of the incoming utility 120v hot lines are no longer 'hot', then it simply means that every other breaker 'slot' would not have power, since they toggle between LEG 1 and then LEG 2 as you go down the panel, at least typically.
Each 240v double-pole breaker, then, would be receiving power to one breaker, while the other one would not. Because they have a common trip handle would not matter, but 'some' of your appliances use one side of breaker for some actions, and the other side for others - meaning that you could have 'part' of an appliance work, while other parts of it don't - there's no way for any 'backfeeding' that I'm aware of.

I suppose, though, that you actually have a problem with your NEUTRAL...
The backfeed occurs when a 240 load is connected to a panel that has a dead leg. The live leg feeds through the 240 volt load and the feedback voltage appears on the dead leg. It can be as high as 120 volts but will normally be lower since there will be other 120 volt loads attached to the dead leg and they pull current through the 240 load and cause a voltage drop.
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Hi all, power is now fully restored. Unfortunately I think the low voltage killed the fridge, it’s just been clicking every few minutes ever since the power came back on. Thankfully, nothing else seems to be damaged.
check the start relay, it's mounted on the compressor.sometimes they go bad.:smile::smile::smile:
Hi all, power is now fully restored. Unfortunately I think the low voltage killed the fridge, it’s just been clicking every few minutes ever since the power came back on. Thankfully, nothing else seems to be damaged.
You may be lucky... the most likely thing that it would harm is the start relay. It has pretty small wire or if a newer type is solid state... either way it's not supposed to be stay engaged but for a second or so. If the voltage was low enough that the compressor couldn't start, the relay would stay engaged and burn down internally on the start winding coil inside the start switch. Now it won't start the compressor when power does return but just pass voltage through to the run winding and the overload Klixon will soon heat up and open the circuit... repeatedly. Unplug it or you risk further damage!

That start relay is cheap. If you're handy, you can replace it yourself.

There may also be a capacitor but it wouldn't likely get damaged by low voltage.

If you're a little more than handy... you can momentarily (one second) short between the start and run winding terminals on the compressor with an insulated handle screw driver when the overload resets and it will start the compressor, if it's still good. That's how a tech will do it and charge you for the trip. That's all the start relay does so no harm. If that doesn't start it running, it's toast.. fubar... not generally worth fixing unless you can do it yourself.

There is always a chance that the compressor has suffered burned and shorted windings. :sad:

Check with your insurance agent and the POCO for any relief you may be entitled to.
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Check with your insurance agent and the POCO for any relief you may be entitled to.
Yes, indeed.

Was the failure of one leg of the service concerned due to a fault in some part of the connection provided to the premises by the POCO?

If so, I suggest they should be just as liable for restitution concerning this fault as they would be if it were caused by either of their two 120 V domestic supply line to the premises concerned connecting with one of their high voltage lines - and there would have been no problem in the unlikely event of BOTH of their split phase 120 V supply lines failing at the same time.

If the wiring at the premises is in good condition and the damage was caused by a problem with the connection provided by the POCO, the company concerned should have an obligation to provide restitution.
Don’t get your hopes up too high on a claim against the utility. Some of them are tougher than your insurance company.

If it is the utilities fault and not act of god, what you collect (at least in calif) is usually actual cash value. (What could you have sold the item for the day before the accident?)

You certainly don’t receive anything close to “replacement value”.
Here when a power issue causes damages the power companies will reimburse you. They do require a contractors invoice stating the damage, what caused it and cost for repairs. I’ve done many of them. Although it’s not always the power company’s fault. We had one where the customer had a surge. Damaged ac and appliances. When I went in the attic the hot water heater was leaning sideways but leaking slightly. The bottom of the hot water heater had moved a couple of feet but not the top. I went downstairs and told them they that had bigger problems then just the ac. Turns out it was a lightning strike. Have also seen issues where the lugs burnt at the meter. That was not considered utility fault.
The linemen who came to do the repair said the connection had come loose at the transformer pole. POCO here is notorious for shady billing and overcharging people so I may just let it go. The fridge is from 1988 so it probably wouldn’t be worth reimbursing anyway. Thanks everyone for the help and input!
The fridge is from 1988 !
You will notice a savings in your electric bill when you replace it. But if the POCO is willing to reimburse don't ignore it.
The most common source of "backfeeding" is an electric water heater. You'll get lower voltage on the bad leg than you do on the good leg, but water heaters just have a heating element which is a resistive load. The one I just worked on had 123vac to neutral on A (the good leg), and 112vac to neutral on B(the bad leg). 8vac A-B. When you turned the water heater breaker off, B dropped from 112vac to neutral to 8vac to neutral. Still waiting on the power company to come out and see if it's their end or my customer's.
@rohodyer, you are responding to a solved 2 1/2 year old thread.
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