CURRENT GOING DOWN GROUND ROD HELP!!!!

[ggunn]

Yes... earth is a parallel path, but usually of significantly higher resistance. Grounded-system services use the grounded conductor for grounding on the supply side of the service disconnecting means (SDM). So there typically is no solid grounding-only connection between the SDM and the transformer grounded terminal.

That's what I thought. Could that be the source of the current the OP is seeing?

 

[5 S electric]

That's what I thought. Could that be the source of the current the OP is seeing?

There is no grounding conductor from the SDM to the Transformer. We even separated are GES thinking that was our parallel path.

 

[5 S electric]

 

[kwired]

Can you now draw in how the other (questionable) service that was earlier mentioned is connected so we may see potential parallel paths between the two?

IIRC it was from a different transformer - but any grounded conductor or bonds between each system potentially introduces current to the grounded conductors associated with the other system.

 

[Smart $]

Thanks for the drawing.

As kwired noted, we also need the other transformer in the 'picture'... and also the primary [ground, grounding] of the transformers.

Another possible contribution are 'wired' communications which are grounded both at the building and to primary ground. As I said, you have to include all connections... even interconnecting metal conduits, if applicable.

If I get a chance I'll put together a drawing that's a little better structured... and if its incorrect you can just print it out, make mod's, then take a picture with the mod's. But don't let that hold you up in any way... hard to tell when I'll get a chance to do it.

 

[kwired]

Thanks for the drawing.

As kwired noted, we also need the other transformer in the 'picture'... and also the primary [ground, grounding] of the transformers.

Another possible contribution are 'wired' communications which are grounded both at the building and to primary ground. As I said, you have to include all connections... even interconnecting metal conduits, if applicable.

If I get a chance I'll put together a drawing that's a little better structured... and if its incorrect you can just print it out, make mod's, then take a picture with the mod's. But don't let that hold you up in any way... hard to tell when I'll get a chance to do it.

Here is my drawing, how I interpreted it from OP's ubmitte drawing please correct anything that is not right


I noted on there some lines that are not necessary and elimination of those lines will reduce potential parallel current from the GEC, which possibly may be very difficult to remove all GEC current. WE still would need to draw in the other mentioned service and how it is bonded to this one and we may see other current paths

After posting and looking one more time I see I should have commented that the direct connection between the generator and GES is not necessary either - this puts this path and the equipment grounding conductor to the generator in parallel as well and that path should also be carrying some parallel portion of the current that is present on the service disconnect to GEC path

 

[kwired]

Here I modified the drawing some to show other buildings, services, etc connected to the primary distribution system.

Assume there is current on the primary MGN, now look at how many parallel paths there are (and assume there are potentially hundreds more transformers and services on the primary distribution system) between the primary MGN on the left of the drawing and the water pipe on the right. This is current that is somewhat unavoidable, but minimizing some of the unnecessary paths pointed out in the first drawing I submitted does help mitigate some of the stray currents that will pass through objects in your facility and divert that current more directly to the GES and water pipe.

 

[kwired]

This is my first drawing again.


I want to point out that if I were to draw the GES to the left of the ATS and generator the parallel paths through the the ATS and generator may not stand out as well in the drawing, but electrically the same paths are still there if I moved that GES box to the left and still connected same conductors to it.

I did not intentionally draw it the way I did for that reason, but my logic of putting the source(s) on the left and the load on the right kind of naturally brought this out.

 

[mbrooke]

POCO like to use the customer's grounds, free neutral and free lightning protection for them

 

[kwired]

I suggest you make you installation look more like this drawing and you will have limited locations for stray currents coming from outside your facility to flow - and of course make sure there are no neutral to ground bonds beyond service equipment. Having the second service (which was earlier mentioned as being questionable) does complicate the situation of stray currents. Disregarding possible code issues with multiple services, from a theory perspective you would want the two services close to one another and single connection from each to common grounding electrode system to reduce parallel paths. But if you have metal structure, metal piping systems, metal duct work or other metal systems in the building it is difficult to eliminate all potential paths and you may always have some stray currents.

 

[Smart $]

Here's what I came up with using 5 S's drawing as the basis for assumptions...

And this shows what I surmise to be all the parallel paths for neutral current from the new system loads...

The main parallel pathways are established through the primary MGN, and for the most part, a result of having two supplies to the same building. While two supplies of the same characteristics is likely a violation, this would be no different than two grounded supplies of differing characteristics.

The GES connections to the ATS and generator could be eliminated. The latter may prevent the generator GFP from tripping while on standby. If there are pathways through communications circuits, I believe ground isolators are permitted. I believe that's the best mitigation possible in the area of altering grounding connections. If safety concerns remain, would have to rely on implementation of equipotential bonding and/or other techniques to reduce touch potential.

 

[5 S electric]

I suggest you make you installation look more like this drawing and you will have limited locations for stray currents coming from outside your facility to flow - and of course make sure there are no neutral to ground bonds beyond service equipment. Having the second service (which was earlier mentioned as being questionable) does complicate the situation of stray currents. Disregarding possible code issues with multiple services, from a theory perspective you would want the two services close to one another and single connection from each to common grounding electrode system to reduce parallel paths. But if you have metal structure, metal piping systems, metal duct work or other metal systems in the building it is difficult to eliminate all potential paths and you may always have some stray currents.

I appreciate all of your guys help. They let us shut off the power to two panels this morning. We found 3 # 12 neutrals going to ground. Didn't help the amperage going down the GEC but helped get it off the grounding wire going to one of the disconnects. I am with you there are multiple parallel paths on the grounded and grounding conductors. I don't think we will ever get all current off of the GES.

 

[kwired]

I appreciate all of your guys help. They let us shut off the power to two panels this morning. We found 3 # 12 neutrals going to ground. Didn't help the amperage going down the GEC but helped get it off the grounding wire going to one of the disconnects. I am with you there are multiple parallel paths on the grounded and grounding conductors. I don't think we will ever get all current off of the GES.

And the current on the GES is not objectionable current - to the NEC anyway. If you removed all equipment and just ran a conductor from utility MGN to your GES - it will likely still have same current - it is coming from outside your facility. If that current level is rather significant you may want to get POCO to look into why - they could have bad connection(s) on the MGN somewhere that are contributing to this.