Residential service;under load A phase=140V B phase=99V - Electrician Talk - Professional Electrical Contractors Forum

litemkr · 09-07-2009, 12:44 PM

Neighbor with 1950s house and upgraded service(era 1970s) original complaint of dim lights but recently has several appliances and loads not working at all. First thing I checked was service voltages and connections at overhead drops=120/240V and good connections. But after further trouble shooting determined that once a large load was introduced(fridge or window A/C) voltage measured at line side of meter was way off, like I mentioned one leg was 140V and the other 99V. Moving the load to an altering phase moved the according measurement too. When I turn the main off, service voltage measurements return to normal.

Their service is one of those combo meter base/breaker panels where overhead mast conductors land at lugs, bus bars to the meter, bus bars to main breaker, to panel bus bars. Bonding jumper and GEC and ground rod all have good connections. All neutrals have good connections and are sufficiently sized.

I suspected a lost/intermittent neutral but never found one.

The overhead triplex and pole mounted XFMR appear fine (from the ground visual inspection) and neighbors sharing this XFMR don't report any problems. But my gut is telling me this has to be a utility based problem, and neighbor has a call in to power co. to come out to check but I'm sure we won't see anyone 'til after the holiday.

Does anyone have a similar experience or ideas of anything else I can check? THX

480sparky · 09-07-2009, 12:46 PM

Classic open neutral.

Keep looking at every connection and every terminal and ever splice. It's there somewhere.

EBFD6 · 09-07-2009, 12:58 PM

Yep, definitely lost your neutral.

Call the search party.

It'll probably be in the last place you look, usually is.

Toronto Sparky · 09-07-2009, 01:11 PM

Corroded slice on service entrance neutral ?

charlie Bob · 09-07-2009, 03:31 PM

Like everybody said, open neutral somewhere.
Once i had a tipical open neutral case i couldn't find the dog-gone thing for nothing. Checked everything, nothing.
Finally after 2 hours, when back outside and looked at bare neutral over head from trans., bingo!!
The neutral messenger was cut in half. Very hard to see though from the ground.
It's there somewhere.

InPhase277 · 09-07-2009, 10:15 PM

You already said the voltage at the line side of the meter was way off (how you checked that under load, I don't know). If that is indeed the case, it's time to call the power company and let them handle it.

MDShunk · 09-07-2009, 11:59 PM

Quote:

Originally Posted by InPhase277

You already said the voltage at the line side of the meter was way off (how you checked that under load, I don't know).....

I've often accomplished that by sticking meter probes in the end of the tap covers.

GEORGE D · 09-23-2009, 07:11 PM

Make sure the water-line is bonded. I know its the last thing you would expect, but I bet its your problem.

JohnJ0906 · 09-23-2009, 07:22 PM

Quote:

Originally Posted by GEORGE D

Make sure the water-line is bonded. I know its the last thing you would expect, but I bet its your problem.

All that would do is cause the water line to carry the neutral load. It would not only merely cover up the real problem, but also be a serious hazard.

Amp1906 · 10-27-2009, 04:27 PM

Check the service drop connections. Sometime they will become loose if the old and you have work done on roof. Someone may have caused this. eg..a ladder may have hit the conductors.

Joe Tedesco · 10-27-2009, 06:11 PM

Quote:

Originally Posted by Amp1906

Check the service drop connections. Sometime they will become loose if the old and you have work done on roof. Someone may have caused this. eg..a ladder may have hit the conductors.

I would also check to see if the terminations at the service point are made with the correct types that are designed and listed for that purpose, such as AL/CU, etc.

It is not uncommon for those splices to have been made using Romex®
connectors!

When a grounded conductor (neutral) is lost the system voltages go crazy and lead to equipment damage. That happened here in IRAQ last year when a generator change out was not inspected properly! The work was done by people who have no electrical experience and who were not licensed electricians and didn't even speak english!

Their Expat electrical supervisor was no where to be found.

He was fired and sent home!

PS: There are over 35 different languages spoken here!

te12co2w · 10-27-2009, 07:30 PM

Quote:

Originally Posted by Joe Tedesco

PS: There are over 35 different languages spoken here!

How does anyone get anything done? I get frustrated when no one speaks English here.

guschash · 10-28-2009, 05:36 PM

I would call the POCO have them ckeck the X-former at the pole. I had the same thing happen. What threw me off was the HO said the POCO said everything was ok at the pole. Told him call again different crew showed up, open neutral at the X-former.

gus

Stator · 10-31-2009, 03:31 PM

Quote:

Originally Posted by JohnJ0906

All that would do is cause the water line to carry the neutral load. It would not only merely cover up the real problem, but also be a serious hazard.

Ya it would cover up the real problem, but a serious hazard.....

JohnJ0906 · 11-01-2009, 05:37 AM

Quote:

Originally Posted by Stator

Ya it would cover up the real problem, but a serious hazard.....

If you don't think it is a serious hazard, why don't you ask the families of plumbers who have been killed by it?

Stator · 11-01-2009, 08:31 AM

Quote:

Originally Posted by JohnJ0906

If you don't think it is a serious hazard, why don't you ask the families of plumbers who have been killed by it?

Why are they taking the ground off in the first place??

So if the neutral is grounded properly back at the tranny your still not going to get a leathal shock? Explain...

JohnJ0906 · 11-01-2009, 08:57 AM

Quote:

Originally Posted by GEORGE D

Make sure the water-line is bonded. I know its the last thing you would expect, but I bet its your problem.

Quote:

Originally Posted by JohnJ0906

All that would do is cause the water line to carry the neutral load. It would not only merely cover up the real problem, but also be a serious hazard.

Quote:

Originally Posted by Stator

Ya it would cover up the real problem, but a serious hazard.....

Quote:

Originally Posted by JohnJ0906

If you don't think it is a serious hazard, why don't you ask the families of plumbers who have been killed by it?

Quote:

Originally Posted by Stator

Why are they taking the ground off in the first place??

So if the neutral is grounded properly back at the tranny your still not going to get a leathal shock? Explain...

My posts are in response to the 1st quote above. The bond to the water, in the case of metallic water service, will provide an alternate path for the neutral current - through the pipes to a neighbors house, through their water bond and neutral, back to the transformer.

Quote:

Originally Posted by GEORGE D

Make sure the water-line is bonded. I know its the last thing you would expect, but I bet its your problem.

The quote here is absolutely incorrect. The water pipe bond will only cause the true problem (open/loose service neutral) to be masked, by providing an alternative path.
If a plumber removes a water meter without jumping it 1st, and there is neutral current present, there is certainly the risk of a potentially lethal shock. He does not need to remove the ground for this to occur.
Note - many water meters here are not in the house, where there is a requirement for us to install a GEC jumper, but at the street - off customer property.

Toronto Sparky · 11-05-2009, 02:53 AM

Here is the tranny feeding my house.. See a bonding ground? I don't!

mavajo3 · 11-14-2009, 07:26 PM

loose netural just got done fixing one today on a service that had copper entrance cable and the netural in the meter socket was not tight and corroding tighted and problem fixed and now i recommend a new service

bobelectric · 11-16-2009, 04:29 AM

Quote:

Originally Posted by guschash

I would call the POCO have them ckeck the X-former at the pole. I had the same thing happen. What threw me off was the HO said the POCO said everything was ok at the pole. Told him call again different crew showed up, open neutral at the X-former.

gus

I thought Pogo died. (Walt Kelly).