Power Company Loose Neutral?

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The OP description of voltages is the epitome of a bad neutral. The fact that the two voltages add to 241 shows that it's the neutral, and not a phase.
 
This is the textbook open or loose neutral. take a 240 volt battery and put 2 100 ohm resistors in series. each one drops 120 volts from a and b phase to the centertap. Now turn on annother light in the den and disconnect the neutral oh by the way the den light is on a phase. the 2 100 ohm loads in paralell equal a combined load of 50 ohms which is now in series with b phase which is 100 ohms. total circuit impedence is 150 ohms now so 80 volts will be dropped across a phase the heavier load and 160 volts across b phase the lighter 100 ohm load. Sound familiar?? the lighter load side will be hit with higher voltage until the devices connected burn ,short or open up and keep swinging the voltages back and forth until everything on the circuits are burned up. Unless the overcurrent protection devices exceed thier ampere trip ratings they will not trip. This is a very dangerous condition which should be addressed IMMEDIATELY!
 
quogueelectric,

Do you think the open / loose neutral is inside the house?

Back at post #0:
mkgrady said:
The customer is going to call the power company to check their neutral before I look any further.
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Maybe Mike (mkgrady) can give us an update?
 
I had a problem once where I knew that it was a bad neutral (lights getting brighter under load instead of dimming, etc.) I even thought I knew which circuit it was. After about an hour and a half of looking I couldn't find anything. Finally I went outside and looked around and there was the neutral hanging by one strand at the pole.

Also found a tree growing around the drop one time, and by that I mean the drop was completly enveloped by the trunk, and one phase was broken inside of the tree.

Sometimes you have to think and look outside of the box.
 
The POCO had a loose neutral. They said it was a bad connection at the weatherhead. I think it was further upstream. While they were there they condemned the service entrance cable because it is aluminum. It turns out the customer had the service changed a couple of years ago without telling the power company or pulling a permit. The work was done to upgrade from 100 to 200 amps so central AC could be installed. I spoke with the POCO for my customer and they want the SE changed to copper to meet the town's standard. I'll do that some time soon.

Now why I don't believe the loose neutral was at the weatherhead: I was called to the customers house a few weeks ago for a different reason. They kept loosing power to half the house. The POCO had already been there and said their lines to the house were OK. They were not. The customer had been shutting off their MCB and resetting it each time they lost one leg. Of course they didn't know what they were doing but a neighbor suggested it and it did turn their power back on. After loosing power several times I was called. After spending 2 hours looking for a problem inside the house I looked at the OH POCO line feeding the house with binoculars. I could see a splice that was charred. I contacted the POCO and they came right out. They replaced the splice and the drop to the house from the nearest pole. The neutral they say was loose at the weatherhead was spliced by the POCO. They even borrowed my allen wrench to make it tight. I watched them crank it down. I suspect the loose neutral was further upstream on an old splice like the one that failed a few weeks ago. After I spotted the charred splice the POCO credited the customers account for the amount of my invoice. I suspect they did not want to have to do it again for the loose neutral so they blamed the CU/AL splice at the weatherhead. A good strategy on their part because the town doesn't allow aluminum.
 
textbook open neutral

textbook open neutral

In my experience the open neutral is usually at the utility companys side. Hastily installed alluminum conductors you get the picture it can get really ugly. Usually a connection on the service latteral neutral. Unless you can see that the service was done by a real hack the grounding on all of the houses on the xformer would have had to all failed which is very unlikely but I have seen it happen on more than one occasion. 40 years ago anything would fly with the inspectors. The ground rod and waterpipe ground will clanp the voltage to a certain point however the more unbalanced the current gets the worse the condition becomes and the harder it is to hold the voltages at a stable level Once the ground connection becomes open the 240 volt xformer puts a phase and b phase into a dynamic series parallel circuit which is not the 120 volts the equipment is designed to operate at. Fire and burned out equipment usually result.
 
loose open neutral

loose open neutral

The key here is also the voltages under load. When I was a little baby electrician I was sometimes fooled by the pwer would stabilize when you shed the load and everything seemed fine then you reconnect the load and all hell breaks loose.
 
quogueelectric said:
The key here is also the voltages under load. When I was a little baby electrician I was sometimes fooled by the pwer would stabilize when you shed the load and everything seemed fine then you reconnect the load and all hell breaks loose.
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You're not the only one. Last week, we got called to a home with exploding bulbs and damaged electronics, along with the usual symptoms. The POCO guys swore the voltages were proper and there was no poor connection.

Too bad they only checked while the main breaker was off. :rolleyes:
 
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