Doorbell transformer causing major load inbalance on Main.

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aelectricalman

aelectricalman

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I went to a home where I recently performed a rewire. After hooking up the range we noticed the burners were not heating up properly. You could lay your hand on the burners while on high. Anyhow, when we checked the voltage on the receptacle we measured 92V - L1 and 156V - L2. This circuit was a three wire with no neutral, so measurments are to ground. Ok, we first tested the system without the range turned on and we still had the same problem. We then checked the main and lo and beho it to read 92 and 156 respectively. So, one at a time we cut off every breaker until we came across a doorbell transformer that was hooked to a 20 amp single pole breaker. When we cut off the breaker servicing the doorbell, the load balanced out a 118v and 119v respectively. The doorbell transformer was hooked up correctly and appeared to be in good working order but there was something going on in the transformer that I cant figure out. I could see if the transformer was hooked up backward there being problems but what if there was a loose neutral on the transformer, could it cause such a swing. Can anyone produce documentation of this in such a small scale as a 120 to 24V step down xfmr. That is an awful big swing, I think?
 
My best guess would be that this is some how being caused by the breakers not seating in the panel correctly, maybe the clip that grabs the buss it not contacting well and the act of turning off the door bell breaker is somehow seating the other breaker feeding the range. ?
 
Just a simple home cheap doorbell.

Just a simple home cheap doorbell.

Nothing fancy. 12v or maybe 24v. Small nonetheless. It says ding dong. lol
 
Did you measure the system voltages with the range on?

Where there any other loads in the house besides the range and the doorbell?

With the doorbell breaker off, did the range work correctly?

-Jon
 
Why hasn't someone talked about a loose or open service neutral yet? After all, that's pretty much the one of the very few ways you'd ever get a high H-N reading like he got at 156V.
 
mdshunk said:
Why hasn't someone talked about a loose or open service neutral yet? After all, that's pretty much the one of the very few ways you'd ever get a high H-N reading like he got at 156V.
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My sentiments exactly - the problem is not the door-bell. And it will be the least of the trouble once the building has been raise by fire. The portrait of death will be Daliesque - melted shapes of small appliances bursting into flames, as the Earth breaks loose from it's moorings and careens towards the sun...
"HALLOWED ARE THE ORI"
ori-doci.jpg



Sorry - Star Gate fan...


You have a loose neutral in a panel, main or service conductors - and it could be fairly dangerous......
 
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It was the neutral on the doorbells 120v Circuit that was loose.

It was the neutral on the doorbells 120v Circuit that was loose.

Not the main grounded conductor. I still dont see how it fixed the problem. It seems that only the loose grounded conductor would cause voltages that high.
 
aelectricalman said:
Not the main grounded conductor. I still dont see how it fixed the problem. It seems that only the loose grounded conductor would cause voltages that high.
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I am confused here. Are you saying that a loose neutral on the transformer cause the fluctuation in the service panel? You tightened that and everything was all better.

I can't buy that one. Something else was amiss. For the range and everything else to have the symptoms you suggest I believe you would have to have a loose neutral on the service. I can't understand it being the way you said. Maybe I need enlightenment
 
Dennis Alwon said:
I am confused here. Are you saying that a loose neutral on the transformer cause the fluctuation in the service panel? You tightened that and everything was all better.

I can't buy that one. Something else was amiss. For the range and everything else to have the symptoms you suggest I believe you would have to have a loose neutral on the service. I can't understand it being the way you said. Maybe I need enlightenment
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Your not the only one confused, what does a branch circuit have to do with a panel voltage imbalance...:confused:
 
He said the voltages measured to ground were 92 and 156. The sum is 248. Approximately equal to normal line to line voltage. I believe that the disappearance of the problem and tightening the transformer circuit neutral was co-incidental. There is still a service neutral problem somewhere.
 
No, Im saying by tightning the neutral on the circuit feeding the doorbell, the problem was fixed. Yeh, I dont get it either, but Im going back to recheck the main grounded conductor one more time to make sure im not overlooking anything.
 
nakulak said:
I think maybe he failed to specify the doorbell transformer he is using:
15.jpg
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Now that is a door bell.does it vibrate the button pusher???

It does sound wierd but what if the transformer was just about a dead short??what is the ohm reading how about is it 120v to 24 or 240 to 24? It still sounds weird like maybe you have gremlins...
 
I'm with acrwc10 in post 4- something jarred back into contact whilst correcting the doorbell connection- maybe the neutral bar just wasn't getting good contact
 
RayS said:
I'm with acrwc10 in post 4- something jarred back into contact whilst correcting the doorbell connection- maybe the neutral bar just wasn't getting good contact
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Which mean is will happen again and again over time......

It may not be a fully connected - but just resistive connection. From the OP I am assuming (hopefully) thet the building just recently rewired and possibly (hopefully again) unoccupied. And that this was discovered while checking the install.... There may only be a few lights here and there on.... And if the panel is properly balanced in terms of load or unloaded - it may seem OK. Tightening the DB neutral in the bar may have jiggled the feeder neutral enough to get a slightly better contact - making it appear the problem was gone.... This could come back at any time?! And if it does with anything expensive or while the building is occupied it could cost you plenty!!!

IMO I would test this with some disposable loads.... (Meaning something cheap - like a half dozen or more 500w flood lamps.) Disconnect or shut-off all 120 loads (like this door bells transformer) then apply the load of the flood lights for a period of time one one phase then the other. When the condition reappears check all the neutral connections with an IR thermometer - the hot or warmer one is loose.... Or for that matter shut all off, and go around and yank on all the neutral connections....
 
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