Trouble with primary winding on transformer

[mike d373]

Why would the primary winding open 2 days in a row?
This customer had major electrical issues a few months ago but he claims
He had them fixed. The problem is on a 4 yr old Carrier but I think its in
His wiring. Any help is appreciated, thanks.

[air1]

Please describe the major electrical issues. I don't think I've ever seen the primary windings of a xfmr go.

[SgtBone]

The last few i have seen other than direct shorts have been low voltage coils with 0 resistance ie, contactors

[mike d373]

He has half the house on the same circuit as the furnace. A few months ago the breaker kept tripping and the kitchen lights were blowing out. He said electrician found some bad nuetral connections but didnt run seperate line for furnace only. I told him the furnace needs its own breaker, but this guy was a contractor for 50 years and knows everything.

[Elfshadow]

The only times I have seen the primary side of a transformer blow is when it has taken to much voltage. Some one in our shop will use the tap for 208 on a unit that's meant to run on 460. Have you verified correct voltage for the system?

[fartbutstudly]

Codes everywhere require that, the heating equipment be on it's own desingnated circuit.
If half of the house is also on heating circ. " anything goes " as far as what the cause could be.

You told the customer the right thing, " Put the equip. on it's own circ. "

When I give customers my pro. advice, and they still " Don't listen "

Many times I " FIRE EM' "

[timebuilder]

He has half the house on the same circuit as the furnace. A few months ago the breaker kept tripping and the kitchen lights were blowing out. He said electrician found some bad nuetral connections but didnt run seperate line for furnace only. I told him the furnace needs its own breaker, but this guy was a contractor for 50 years and knows everything.

Bingo.

This buzzard is using multiwire branch circuits. When a neutral opens, the voltage goes from 120 to 240 on whatever is connected.

That's why he is losing transformer primaries.

[philjafo]

You've told him what needs to be done to correct the problem, maybe after he buys 15 or 20 xfmers from you at full price he might decide to fix the real problem.

[mike d373]

Unfortunately hes still in warranty. I told the boss whats going on and hes gonna have to tell him because he doesn't want to hear it from me. Yes i had 118 volts to furnace.

[philjafo]

Failure to correct the real problem will usually void any warranty, check with the warranty provider. At least that's what I would tell the customer.

[timebuilder]

Unfortunately hes still in warranty. I told the boss whats going on and hes gonna have to tell him because he doesn't want to hear it from me. Yes i had 118 volts to furnace.

Loose neutrals on multiwire circuits can still read 120 most of the time. It's when that contact breaks...for just a moment......

[Birmingham]

Bingo.

This buzzard is using multiwire branch circuits. When a neutral opens, the voltage goes from 120 to 240 on whatever is connected.

That's why he is losing transformer primaries.

I fully agree with this. i got the ---- shocked out of me by a "dead neutral" because of a back feeding circuit. same situation with the transformer. interesting that the board in the unit will take that.

[Andr00]

He has half the house on the same circuit as the furnace. A few months ago the breaker kept tripping and the kitchen lights were blowing out. He said electrician found some bad nuetral connections but didnt run seperate line for furnace only. I told him the furnace needs its own breaker, but this guy was a contractor for 50 years and knows everything.

BTDT. Last one was at a home that a young couple lived in. They had just bought the house from a guy who was a handyman legend in his own mind. Why wouldn't you wire your entire finished basement and half of your kitchen on the same circuit as the furnace?

When I told her on the phone what was going on (nobody home while I was there), she said she wasn't surprised due to all the other things that had gone wrong since she bought the place, and that it was probably no coincidence that the fridge and disposal had stopped working too.

"*blink blink* Well, I left the bill for our time on the kitchen table. Call an electrician."