3 or 4 Wire required.

[JPD]

My brother in law had a new service put in maybe 20 years ago. Power comes from the pole to the main, about 15 feet, then from the main to the house about 400 feet. They ran 3 wires from the main to the house and a ground rod at each. At the house I have mega resistance between the ground and the neutral at the house. Should there have been 4 wires? Can this cause a problem when connecting a generator?

Thank You

 

[petersonra]

My brother in law had a new service put in maybe 20 years ago. Power comes from the pole to the main, about 15 feet, then from the main to the house about 400 feet. They ran 3 wires from the main to the house and a ground rod at each. At the house I have mega resistance between the ground and the neutral at the house. Should there have been 4 wires? Can this cause a problem when connecting a generator?

Thank You

There should be a low resistance between neutral and the equipment grounding conductor, no matter where it is measured.

The resistance from neutral to earth (dirt) could be just about anything.

The situation you describe is not going to create any extra problem from connection with a generator.

HOWEVER, if there is no connection from neutral to the equipment grounding conductor, this is a big problem.

You need to get a competent electrician out to look at it PDQ.

 

[LarryFine]

At the house I have mega resistance between the ground and the neutral at the house.

The house's neutral and grounding should be tied together at the service disconnect, and not again downstream. In your case, with a 3-wire feeder, that would be the main on the house, whether in the panel or an exterior main disco.

 

[JPD]

I'm an industrial guy and always understood that after the main would be 4 wires. I will talk to the Inspector and see what he has to say.

 

[LarryFine]

The disco at the pole might not have to be considered the main, allowing the 3-wire feeder.

After 20 years, I would correct the neutral-ground bond and not involve the inspector.

 

[JPD]

The ground bar is connected to a ground rod at the house and the neutral is connected to a ground rod at the pole where there is a main breaker. There is a main CB at the panel also. I'm thinking I should install a bonding jumper at the house between neutral and ground. Should I drop the ground off at the pole?

 

[LarryFine]

I'm thinking I should install a bonding jumper at the house between neutral and ground.

Absolutely, yes, immediately! Install either the correct bolt, or an appropriately-sized conductor between buses. But, do it while the power is off, or you might find out the hard way why it should have been done!

Otherwise, without the bond at the separate (from the pole) structure, you're asking the earth between the house and the pole to conduct hot-to-EGC faults, which is not nearly enough current to trip breakers.

This creates the risk that everything in the house that should be able to reliably be considered as grounded could become energized compared to earth. That's capable of more than enough current to hurt people.

Should I drop the ground off at the pole?

No. The neutral should be grounded (earthed) once at each separate structure.