Ask Me Help Desk - Possible open neutral

Possible open neutral

The power in my home will work perfect for days even weeks then for no reason lights blink and power drops and surges occur.If a heater is on when it occurs ,the heater fails and TV even turns off until heater is turned off.When testing voltage during problem one cicuit will drop 10 to15 volts while another surges about the same.If turning on a small blow dryer on one line lights brighten in one room and dim in other also voltege surges on other line 35 to45 volts and drops on line its pluged to about the same.This occurs on all circuits in house.Could this be a open main on power company hookup or what?

Could be on your side or the power company's.

So this has been happening for weeks you say?? Have you called the power company yet?
I'd say it's time. Actually it was time weeks ago!

What the hell are you waiting for?? Pick up the phone!!

If you've got an open neutral, then you'd get normal voltage between active and earth (hot and ground)

Quote:

Originally Posted by aidos

If you've got an open neutral, then you'd get normal voltage between active and earth (hot and ground)

This is not always true. It depends on where the open is.

With an open neutral on the power company's side the current is still trying to get back to it's source how ever it can. Because we get our "ground" not from the earth but from the neutral bond in the main panel the current will try to flow through the earth, provided the service has all the proper grounding electrodes installed.
The earth is a POOR conductor so the flow will be very erratic. The only path for the current is through the dirt.

The reason I have'nt called power company yet is that about 3 months ago this problem started occurring again, then a PG&E guy showed up in my yard.He said he was there to change the gas meter and the electric meter. I asked him about my problem, he said call company. He installed the new meters, after which the problem was gone.Not one thing went wrong for 3 months so I assumed when he changed the meter it somehow fixed the problemThen 3 days ago it returned worse then ever.As far as the ground to earth reply, the home is 50 years old and for some reason there doesn't appear to be any type of ground connecton any where near the meter box.

Ok... it's been 3 days... CALL THE POWER COMPANY

"Because we get our "ground" not from the earth but from the neutral bond in the main panel....."

This is WRONG!! The neutral and ground are bonded in the service box but the GROUND better be froma grounding source ,i.e. GROUND ROD or cold water pipe.

Back to the question. I had a customer that had lights occasionally dimming or getting brighter and occasionally got a mild shock in the shower(EEK! ). He had called electric co and they checked outside neurtal and all was fine. He then called me and I checked grounds and neutral in service box... BONDING screw in service box was loose!! Tightened in and all was solved.
If the Power Co says everything is OK outsied then you need to have an electrician check the
Service entrance and box. The power co will only check what comes to the house outside.

DO IT NOW!!

Quote:

Originally Posted by Handyman2007

"Because we get our "ground" not from the earth but from the neutral bond in the main panel....."

This is WRONG!!! The neutral and ground are bonded in the service box but the GROUND better be froma grounding source ,i.e. GROUND ROD or cold water pipe.

Sorry sir, but YOU are WRONG!! Scary wrong. :rolleyes:

The earth serves NO Purpose in protecting you from short circuits and to aid in tripping overcurrent devices.

You tell us, what purpose do you think a ground rod serves? I patiently await your response.

If you were to actually trace the neutral back through the power companies lines, you would see that the neutral is actually GROUNDED at somepoint along the service route. Why is it that you can wire a 220 appliance with three wires(red, black and ground) without the use of a neutral? It is because , as I stated before, the neutral, at some point in the service route, is actually at EARTH ground potential.
The actual neutral serves as a reference or Zero point when looking at voltage output (as in a transformer). But in most safe and dedicated power distribution systems, the neutral is grounded to earth ground. Without it , lightning and other spurious voltages would have no place to go and would destroy distribution equipment and KILL PEOPLE.

PS: The reason we are reequired to bond the neutral service line and earth ground is to PROTECT the power companies equipment... so apparently the Earth ground serves some useful purpose.

Quote:

Originally Posted by Handyman2007

If you were to actually trace the neutral back thru the power companies lines, you would see that the neutral is actually GROUNDED at somepoint along the service route.

No, it is grounded to the earth at several points. So what?

Quote:

Originally Posted by Handyman2007

Why is it that you can wire a 220 appliance with three wires(red, black and ground) without the use of a neutral? It is because , as I stated before, the neutral, at some point in the service route, is actually at EARTH ground potential.

The earth, or a neutral, serve absolutely NO purpose in a 240v circuit. A 240v circuit is a line to line circuit. Nothing grounding or grounded comes into play. A 240v circuit will function perfectly without a ground. The reason for an equipment grounding conductor is to carry fault current back to the source, at which point the branch circuit or main breaker interrupt the current flow.

Quote:

Originally Posted by Handyman2007

The actual neutral serves as a reference or Zero point when looking at voltage output (as in a transformer). But in most safe and dedicated power distribution systems, the neutral is grounded to earth ground. Without it , lightning and other spurious voltages would have no place to go and would destroy distribution equipment and KILL PEOPLE.

THIS you are correct on. THAT is the ONLY Purpose for connecting our electrical systems to the earth.
This has NOTING to do with fault current.

Quote:

Originally Posted by Handyman2007

PS: The reason we are reequired to bond the neutral service line and earth ground is to PROTECT the power companies equipment

I'll say again: WHAT??
NO, the reason for the neutral to ground bond is so that the equipment grounding conductors run with circuit conductors can carry fault current back to the source and allow the breakers to do their job. Without that bond the fault current would simply flow into the earth and create a dangerous condition.

I strongly suggest you read and understand NEC 250.4

Here is a relevant section. Please see the last line:

250.4(A)(5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. It shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.