Objectionable current

[dbuckley]

Also, I'd like to add that I don't see how "multiple neutral to ground" connections is relevant. Though not a good thing I'm having a hard time seeing how it would affect current at a ground rod.

If there are multiple neutral to ground connections (eg one at transformer pad, one at service entrance) then the ground is acting as a parallel conductor to the neutral conductor. if current flows through the neutral, it will also flow through the parallel path - the ground.

 

[ike5547]

If there are multiple neutral to ground connections (eg one at transformer pad, one at service entrance) then the ground is acting as a parallel conductor to the neutral conductor. if current flows through the neutral, it will also flow through the parallel path - the ground.

That goes without saying and I thought it was assumed by all. I was referring to connections down stream on the building premises.

Edit to add: I thought the OP was referring to connections after the building main(s) as well.

 

[dbuckley]

That goes without saying and I thought it was assumed by all. I was referring to connections down stream on the building premises.

In message 19 you noted: I'd like to add that I don't see how "multiple neutral to ground" connections is relevant.

There shouldn't be multiple neutral-to-ground bonds after the service entrance bond and ground rod.

However, the more (or better) ground rods there are that are correctly connected, the more current will flow through the ground, as the ratio of neutal to ground resistance will change.

 

[ike5547]

In message 19 you noted: I'd like to add that I don't see how "multiple neutral to ground" connections is relevant.

If you're going to insist on misunderstanding me that's your prerogative. I assumed everyone knew that the grounded conductor is connected to earth at both the transformer location and the customer premises. I was referring -- and I thought the OP was referring -- to connections on the customer premises downstream of the main as if that were causing a problem at the electrode(s). If you look back to a previous post you'll note that I acknowledged that some current flow to earth is normal -- or words to that effect.

I wasn't aware at the time that every word would be parsed and scrutinized for possible inconsistencies or I would have had it drafted by an attorney.

 

[ike5547]

Here is the comment that prompted my comment.

My feeling is that the primary cause of the current we are finding is the result of the neut and ground being bonded and rebonded and rebonded along the way. Where we are gen fed I'd say that N-G jumper in the gen combined with N-G jumper in the panel is the most likely culprit.

 

[Jps1006]

It seems to me that the most likely causes for this current are multiple paths to ground and if someone servicing this system disconnects a ground splice that has 8 amps flowing across it it would be unpleasant.

Not necessarily. If the 8 amps is the result of parallel neutral current, opening the ground would prove to be quite uneventful, as the 8 -amps would find its way back to source through the neutral... provided everything was properly installed and still in tact. And herein lies the issue, you can't determine that by the merely by presence of current.

I also agree with the others, deciding on a number to draw a danger line with can be dangerous in and of itself... Although I also get from your post you are taking less than ideal conditions and trying to improve.

Might I suggest trying to derive a method that would take some site conditions into consideration? Maybe use a percentage of neutral current as a red flag. Take bonding points and dirt/sand moisture conditions, distance between bonds, etc into consideration and you might find this objectionable current threshold to be a moving target. If anything, make that point to the higher ups. You can't say 8-amps across the board is acceptable without taking field conditions into account, and therefore justify your lower threshold as rationale to get qualified personnel out on site to inspect.