Neutral/grounded conductor issue

[LarryFine]

I have the utility out to a job twice telling me there wasn't an issue. I called the power company engineer and explained the issue and he said "That's a classic neutral problem". I told him I had their guys out twice and I told them that it was a neutral problem. They had it fixed that day.

The problem is if they aren't testing it under load then they will not see the problem.

My exact experience. More than once I've had to tell the POCO buys to check the voltages with the main breaker ON.

 

[yesterlectric]

In old installations sometimes they ran service entrance cable with the aluminum circumferential neutral underground without conduit. It tends to fail eventually. Sometimes you can detect a failed neutral via the use of a clamp around ammeter.

Secondly, if you have an open neutral on the customer side of the service and the utility comes out and tests at their xfmr, they likely won't find the same voltage anomalies you have found. By telling us the two points where you are getting the different readings, you have suggested the two points the failure likely is in between.

 

[don_resqcapt19]

Here's the other point that is bothering me; since the grounded conductor and the grounding conductor are bonded at the panel wouldn't it make sense that there would be a solid path to ground even if the grounded conductor was compromised underground...the cold water bond is 12" from the panel and visible, the ground rod is 6' away on the exterior.

If there is a common metal underground water piping system that is continuous and other electrical services in the area are connected to it, it would act as the neutral and you would not see this issue.

However that is the only grounding electrode system that will have a low enough resistance to do this, and only if the piping system has metal to metal contact at all joints.

In areas with the common metal water piping system that is electrically continuous between the buildings, you can have a completely open neutral and have no symptoms. It is common to find that 20% or more of the neutral current is flowing on the water piping system where you have the continuous metal water pipe between multiple buildings.

 

[Jraef]

Had one recently where it was the neutral jaw on the meter socket being corroded. It was vexing me but I couldn't pull the meter to see it. Called the utility and they found it.

 

[ptonsparky]

Classic example of open or compromised neutral connection as others have said.
Measured L-L voltage is typically the sum of the two L-N. 140+90 =230.

Faulted conductors as shown above often do heat damage to the adjacent. At very minimum Scothcoat them. (Or something similar)

 

[mtnelect]

Do It Yourself "Wire Tracer"

When in my apprenticeship worked with a journeyman doing irrigation wiring repair on golf course's. Remove one of the sparkplugs wires from the service truck, attach a wire from the sparkplug wire to the irrigation wire. Then take a portable radio tuned to a blank station and follow the popping sound to it stops. You have found the break !

Posted on the wrong forum !