Bonding two services @ the same building

[karl riley]

Re: Bonding two services @ the same building

Arney, It seems from your post that you are not following the sense of what is being described. I will try to see if I can describe it simply.

We have two services to different parts of a building. Each service neutral is bonded to a common metal water pipe. Neutral current is created on one service by the difference in phase current. Let's say there is 30 amps of neutral that is headed back to the transformer. It can get back two ways: through the SE neutral, and by way of the water pipe to the other service neutral.

It will divide and go through both, depending on the relative impedances of the two paths.

Forget about the local electrodes stuck in the earth. Their relative impedance is so high that only milliamps will choose that path.

So in this way we have, say, 10 amps going on one path and 20 amps on the other path. One of them includes the water pipe. Whether it is 10 or 20 amps depends on whether one of the service neutrals has a dirty connection relative to the other service neutral.

Make sense?
Karl

 

[pierre]

Re: Bonding two services @ the same building

Hello Photon,
This is very interesting. I believe there is a lot more of this type of problem in the industry than most people realize.
Could it be that the smaller of the 2 services has an imbalance, but the impedance of the larger service is low enough that the current is using the 'bond' between the 2 as it's path back to the source. I know that it will use 'all' paths, but more current will flow on the path of least resistance.
Let me know what you think.
Thanks
Pierre