Broken Neutral??

[Fett]

Hey guys, I have a small under-counter ice machine. Theres nothing wrong with the ice machine, but it is not getting proper power.

This receptacle is 120V 60Hz AC and I put my meter lead on hot side and my other lead on the neutral I read 54 Volts. I then removed the receptacle and ohmed it out at 1.2 Ohms. I then ohmed out a brand new receptacle(we have new ones on hand here) straight out of the box 1 Ohm. I install the new receptacle and repeat my previous test. Still 54 Volts. I check to make sure for proper connection of wires upstream at the circuit breaker and bus bar.

What causes half voltage? Is it because the neutral is broken between the receptacle and the next connection point?

[Frikkie]

It could be a missing neutral.
Test between the hot wire and a good ground or earth. Do you get 110v? If you do then there is a faulty neutral.

Also check you tester is working with a supply somewhere you know is good and correct.

What is a receptacle? Is it the socket where the plug goes into I am thinking?

[Fett]

It could be a missing neutral.
Test between the hot wire and a good ground or earth. Do you get 110v? If you do then there is a faulty neutral.

Also check you tester is working with a supply somewhere you know is good and correct.

What is a receptacle? Is it the socket where the plug goes into I am thinking?


Test from hot to ground is still 54V. It is a 20Amp socket.

I also checked a receptacle upstream on the same circuit. 120V

There is a voltage loss somewhere, I don't know what could cause it though. Not much of an electrician.

[Fett]

Ok guys I had just realized what the problem was.

The receptacle is a GFCI and thus it is a home run. I measured 54V from Common the Neutral and Common to Ground. I was confused?????

That 54Volts was an induced voltage from the three other home runs running through the same conduit!
So at that moment I thought to my self there was a loss of power not a loss of voltage!

I went back to check the source of power and it was the circuit breaker! It had tripped out but the lever had not moved! Faulty circuit breaker.

This ice machine makes some nice ice!!

Fett--

[tbirdtbird]

Glad U found the trouble. On a related note I have uncovered similar faulty breakers with a high internal resistance due to long term over-current or seeming over-current. Not enough to trip them, but enough to burn them up internally. Even though you are allowed constant load of 80% of rating of circuit, this high a constant load is not a good idea. The breakers can be damaged internally and I have even seen burned bus bars from this. It is scary that this kind of heat will not trip the breaker.

I have a lot of confidence in Square-D breakers and panels, they have lots of copper and are well made. There is another competing line which actually has several brands of breakers which are interchangeable. You all know the design/brands I am referring to. Take one of each of the several brands of breakers that will fit these panels and compare the weights by hefting in your hand. See if you notice a difference. My money is on the one that is the heaviest...that tells me there is more to the insides, and I refuse to use the others.

I cannot tell you how many burned panels (bus bars) I have seen that did not trip the breaker when the heat built up. If a high amp circuit seems to be behaving oddly, pull the breaker and look at the bus bar before you condemn the equipment.

[Frikkie]

I am glad you found your problem, I would never have guessed it. I thought that NEC regs for USA specified a separate circuit without RCCD/RCBO or GFCI protection for the refrigerator. Maybe this is wrong or maybe changed.

[Abby Normal]

self edit........op solved problem

[coolhibby1875]

hot,ground and home runs?

[paul_h]

Glad you sorted it out.
Induced voltage is a bitch. We have 240v AC here and I was stuck at a job a few months ago, domestic a/c ducting and dampers with a two winding motor for open/close on the dampers.
240V to the damper motor to open or close, 120v to the other winding in the motor, nothing wrong with the switches or cabling.
Made me scratch my head a bit, where did that voltage come from, I couldn't find anything wrong.

[goshen]

hi there i had the same "problem" the voltage is coming from the other side of the winding u must use a double pole double throw relay to control these damperes

[Fett]

Actually I was hoping everything would be ok over the Labor Day weekend. The problem has re-occured unfortunately. The receptacle is a GFCI because it is in the kitchen. I suspect that the wire is damaged. I am going to replace the GFCI with a regular receptacle and install an arc fault circuit breaker. Perhaps if the arc fault trips then I can assume that there is a break in the insulation and it is arcing to the nearest ground.

I have also discovered this same problem on a GFCI circuit outside on our patio which serves lighting for our flagpole.

Edit: This building and its electrical circuits are not even one year old. We have only been here since November of 08.

Any ideas?

[Frikkie]

Actually I was hoping everything would be ok over the Labor Day weekend. The problem has re-occured unfortunately. The receptacle is a GFCI because it is in the kitchen. I suspect that the wire is damaged. I am going to replace the GFCI with a regular receptacle and install an arc fault circuit breaker. Perhaps if the arc fault trips then I can assume that there is a break in the insulation and it is arcing to the nearest ground.

I have also discovered this same problem on a GFCI circuit outside on our patio which serves lighting for our flagpole.

Edit: This building and its electrical circuits are not even one year old. We have only been here since November of 08.

Any ideas?

Replacing the GFCI receptical with a regular one will not find the fault, it only treats the symptoms. If there is a insulation fault and a poor appliance earth then the GFCI could be saving the customer from getting a shock. Please rather find the fault.

You need to have a Mega tester and test the insulation of the appliance and the house wiring as well. Also do all the usual wiring tests like loop impedance and check with your eyes for bad connectors or moisture damp problems or even ants/****roaches/rats damage all the way along on that circuit.

[Fett]

Replacing the GFCI receptical with a regular one will not find the fault, it only treats the symptoms. If there is a insulation fault and a poor appliance earth then the GFCI could be saving the customer from getting a shock. Please rather find the fault.

You need to have a Mega tester and test the insulation of the appliance and the house wiring as well. Also do all the usual wiring tests like loop impedance and check with your eyes for bad connectors or moisture damp problems or even ants/****roaches/rats damage all the way along on that circuit.

I don't have a Megger. :(

Well we can definitely rule out rats, because all the wiring is in conduit since this is a commercial office building/warehouse (assuming they are not the man eating rats of new york city). I don't know about ****roaches though... they spray this place every friday and I've never seen any as of yet. I have put an arc fault circuit breaker in the circuit and that should detect the slightest spark if any spark at all.

I have gone through twice now and tightened all connections/wire nuts/circuit breaker.

The bus bar is not burnt or charred.

I will run through a few more things that I can think of. Will post back.

[Fett]

hot,ground and home runs?

Yes, these are electrical terms! Hot(usually black wire), ground(usually green wire) and home run means that power comes directly to this device from the circuit breaker. A GFCI Receptacle(the one usually in the kitchen or bathroom with the test and reset button) should be a home run, if it is not then it is not wired properly.

[tbirdtbird]

Well we've all seen wire damaged from a pull in conduit. THHN? THW? THHN is harder to damage. I hope this is not the issue. Are you certain this is a home run and there is no other electrical joint made up anywhere? This isn't coming from a sub-panel with poor wiring workmanship? Can you pull out any of the wire from the box to check for chafing or anything? I got lucky once the fault was a nicked wire just inside the conduit was able to pull out a few inches of wire and start fresh. That is rare tho.

Also some GFI breakers can be hair trigger I'd do just what U are doing and eliminate it it for now as part of your troubleshooting.

I assume the neutral at the panel bussbar is tight.

[Fett]

Well we've all seen wire damaged from a pull in conduit. THHN? THW? THHN is harder to damage. I hope this is not the issue. Are you certain this is a home run and there is no other electrical joint made up anywhere? This isn't coming from a sub-panel with poor wiring workmanship? Can you pull out any of the wire from the box to check for chafing or anything? I got lucky once the fault was a nicked wire just inside the conduit was able to pull out a few inches of wire and start fresh. That is rare tho.

Also some GFI breakers can be hair trigger I'd do just what U are doing and eliminate it it for now as part of your troubleshooting.

I assume the neutral at the panel bussbar is tight.


I have one of those testing instruments that you plug it into the socket and it tells you if it is wired correctly. Well I went around the room to all the outlets with this device plugged in and switched all the breakers on and off to determine what was on each breaker(by watching the lights on my tester go out)

There were four individual GFCI receptacles on this one circuit breaker. The GFCI's are wired in parallel.

I don't understand why they are wired like this.

[tbirdtbird]

Overkill or the electrician had a box of GFI receps he had to use up quick. Or afterthought having not run the other 3 downstream from the first. Not wrong, tho.