No Neutral on service

[GlennG]

Last week i did a panel change, upon turning the power back on i was checking the balance on the neutral only to discover that there wasn't one. All the current was going back on the water main. ( brand new ground rod and WM connections) Upon closer inspection of the old WM connection it seemed like this was probably an issue for some period of time, but either way i called the power company who came out and re-did there connections a few days later. I was just there yesterday to finish some other work, so i decided to check the balance again and make sure everything looked OK , and what i found is a mystery to me. From what i was reading, the difference in phases was now going back on the neutral, however damn close to a mirror image of that same current is on the WM also. How is that possible? Does anyone have any ideas or seen this before?

My only thought is that there is less resistance on the WM that the utility drop ( wm goes strait to street next to pole, originating almost in the same place, just one is above ground and the other below) The other thought was a dirty neutral connection in the meter pan, but if that was the case i would think i would have some kind of split between the returning current, half or WM, half on neutral. Any ideas or help is appreciated. Thanks

 

[Dennis Alwon]

What are the readings?

 

[gar]

120804-1732 EDT

First, turn the main breaker off. How much current on the water line? How much on the neutral?

Assuming the currents are essentially zero, then

Second, turn the main breaker on and all breakers of one phase off. Now measure the above two currents, and the hot current to the loaded side. What are these values?

The neutral and water line currents should sum to about the hot leg value.

If the currents in the water line and neutral are similar, then there is a poor neutral path and a very good water line path for the relatively balanced currents to exist.

Next if there is substantial water line current you would want to measure the voltage drop along the neutral path. Use and assume the ground rod at the transformer is close to the voltage at the transformer center tap. Run a test lead from the transformer ground rod to your voltmeter at the main panel. Be careful, could be substantial voltage. Measure the voltage from the transformer center tap to the neutral bus in the main panel. With a 10 A load I might expect this neutral drop to be less than a volt. Will be dependent upon wire size and length.

.

 

[rt66electric]

smililar problem

smililar problem

I up graded a sevice. The main breaker was "OFF". While connecting the neutral at the top of the service wheatherhead mast Iwas getting approx 5 amp spark from poco areia Neutral to the service entrance conductor. What should aperson Do???? call the POCO and say "chicken-little-the-sky-is-falling-down" , or NOT?????

 

[GlennG]

The readings were fluctuating since the people were home but The neutral current was ranging from 3.5 to abbot 5 amps on both wm and neutral. When I go back I will try those suggestions. I'm almost wondering if the transformer is going bad, or the secondary that comes down then street to feed the house. Could it maybee be some kind of objectional current on everything? If that makes sence

 

[Smart $]

I up graded a sevice. The main breaker was "OFF". While connecting the neutral at the top of the service wheatherhead mast Iwas getting approx 5 amp spark from poco areia Neutral to the service entrance conductor. What should aperson Do???? call the POCO and say "chicken-little-the-sky-is-falling-down" , or NOT?????

Depends on whether the POCO allows you to do service drop to service entrance splices :slaphead:

Otherwise, and assuming the service entrance and service equipment integrity has not been compromised in any way, yes, report it (that is, just the facts ).

 

[Smart $]

The readings were fluctuating since the people were home but The neutral current was ranging from 3.5 to abbot 5 amps on both wm and neutral. When I go back I will try those suggestions. I'm almost wondering if the transformer is going bad, or the secondary that comes down then street to feed the house. Could it maybee be some kind of objectional current on everything? If that makes sence

Until you get the readings, it is just sheer speculation. May be the service you worked on... may be neighbors' (one to many)... or may be POCO's. Anyway way you look at it, it is objectionable current. The question is whether anything can be done about it and what that entails.

...

Second, turn the main breaker on and all breakers of one phase off. Now measure the above two currents, and the hot current to the loaded side. What are these values?

...

Make sure all 2-pole breakers are off, too, when doing this measurement.

 

[PetrosA]

Actually, any time you have a service neutral bonded to the water service and the same at all the neighbors' houses with interconnected water mains, you are going to split the neutral load between the neutral conductors and water pipes for everyone and any house you go into will be showing a current reading within a few percent of all of the neighbors' houses (unless someone has a bad neutral...). There's nothing you can do to eliminate load travelling on the water pipes since they're nice and solidly connected to the neutrals at every house on the street and electricity likes to take every path you offer it. This is why it's so important to place a jumper across the water meter.

 

[GlennG]

Thanks everyone for the replies. Some interesting points were made. I am going to report it to the utility for my own peace of mind to play it safe. I would also like to measure the wm at another house to see what the values are if anything so i have something to compare to.