Transformer failure?

[ishiboo]

Okay, this morning in the middle of my shower I lost water pressure. Assuming it was the 23 year old well pump controller, I went to test things, but my damn DMM wasn't working. I thought it may have been the CH breaker, they seem to fail frequently for me. But I was only getting 17 volts on the breaker instead of 240.

Probing each 120 leg, I got 120v on one and 124v on the other... everything's good, right?

So I went and brought my GOOD DMM back from the boat, and picked up a well pump controller.

Testing with the good dmm, same thing... 17 volts between each 120 leg! It seems that both my 120 legs are now "in sync". I'm assuming this is a transformer failure, we have 3 of our own meters on one transformer as well as the neighbor's house as well. Is this a common failure for a transformer?

 

[SuperSocket]

CH as in Cutler Hammer breaker?

If you are losing breakers at such a rate you probably have a lot more serious power problems. Breakers do not fail very often if ever for most customers... unless of course something was installed wrong or is very wrong.

 

[ishiboo]

CH as in Cutler Hammer breaker?

If you are losing breakers at such a rate you probably have a lot more serious power problems. Breakers do not fail very often if ever for most customers... unless of course something was installed wrong or is very wrong.

It's an old rusty box, I've replaced 3 but the house was unoccupied for some time. The power is fine.

HOWEVER, it's not the transformer... I tested our other two panels and they have 240 just fine. Unfortunately it's the service entrance cable... it must be either shorted or cut and water is bringing the phases together. It's not code as it goes about 30' before hitting the box with no breaker/disconnect, so the plan was to to a new QO panel immediately inside, and feed the old panel with one 100A until I could rewire. Now, it looks like I'll be expending the cash and starting the project IMMEDIATELY

 

[Thruxton]

Is the cable aluminum? The connections to the panel might be corroded, from your description of the scene of the crime.

 

[Jarcese]

This will happen if the high sides melt together and the feed on one of the high sides burns clear. Essentially you are being fed 120 to all circuits and anything that runs on 240 will not work. You will get 120/120/ and somewhere around 0 depending on the meter. I'm a toubleshooter for the power company and I've seen this happen a few times. We do this intentionally occasionally when a customer loses a phase fed from underground so they can have lights in the whole house until repairs can be made. You have to be careful though because you will be running almost twice the load on one phase.

 

[ishiboo]

This will happen if the high sides melt together and the feed on one of the high sides burns clear. Essentially you are being fed 120 to all circuits and anything that runs on 240 will not work. You will get 120/120/ and somewhere around 0 depending on the meter. I'm a toubleshooter for the power company and I've seen this happen a few times. We do this intentionally occasionally when a customer loses a phase fed from underground so they can have lights in the whole house until repairs can be made. You have to be careful though because you will be running almost twice the load on one phase.

That's it. Portions of the cable were underground, I dug it up and one hot leg is completely burned through. It doesn't appear to bridge to the other but it must. It's old and what appears to be cloth-covered copper.

I just have to figure out my replacement plan, it's going to be a huge deal to fix... have to bore a 2.25" hole through 1.5 feet of fieldstone foundation, which will be fun, and I have to get a hold of the electrical inspector, who because we're in a small town is part-time.

 

[Aceman]

Call an electrician. We do underground locates and repairs all the time, it usually doesn't take that long.

 

[Charles (in GA)]

Call an electrician. We do underground locates and repairs all the time, it usually doesn't take that long.

True. While a underground splice may not seem to be the most desirable thing to do, since you have located it, its a piece of cake for someone with the right splices, crimper, etc., and since you are really not prepared to deal with a complete replacement right now, its probably money well spent to hire in someone to splice it.

I had underground service to my house bust, corrode, burn thru, and the power company came out and located the bad spots (there were three) and did crimps with a device that looked like a cordless drill with a special attachment in the place of the chuck. They use heat shrink with sealant inside and it has held up for several years now.

Charles

 

[Aceman]

We do it all the time. Most of the time it's 1000-2500' runs of DB aluminum out to an irrigation circle. It's not fun tracking faults in the middle of an 8' high corn circle!