Multiple Grounding Electrodes

[Rock86]

I pretty confident what I am about to say is correct, but one element has me concerned.

The existing service entrance equipment has a GEC, and bonds the copper cold water pipe. The water piping was modified over the years and cannot be considered a GEC because it transitions to plastic before leaving the building. There is no building steel. We need to install a new ground rods to create a GEC for new transformers because the run is 300+ feet from the service entrance equipment.

If we bring the GEC in, and bond the cold water piping, the two grounding electrode system is technically bonded, but do we need to extend the new GEC all the way back to the Service grounding electrode system?

 

[augie47]

The interior piping can be used to interconnect electrodes if it meets the requirements in 250.68 (C) exception

 

[Rock86]

The interior piping does not qualify as a conductor so you would need to go back to the building GES.

Thank you.

 

[augie47]

Thank you.

Disregard that post.... I had forgotten about the exception I noted in the corrected post. Sorry u answered as I was editing

 

[infinity]

The water piping was modified over the years and cannot be considered a GEC because it transitions to plastic before leaving the building. There is no building steel. We need to install a new ground rods to create a GEC for new transformers because the run is 300+ feet from the service entrance equipment.

So the ground rods are now the building GES (not GEC) therefore they need to be connected to the service.

 

[Rock86]

So the ground rods are now the building GES (not GEC) therefore they need to be connected to the service.

The Service has a GES, but the water piping is no longer a supplemental GEC

 

[Rock86]

Disregard that post.... I had forgotten about the exception I noted in the corrected post. Sorry u answered as I was editing

I still don't meet that exception because of the modification to the piping.

 

[infinity]

The Service has a GES, but the water piping is no longer a supplemental GEC

You stated that there is no water pipe electrode or building steel electrode so besides the ground rods what electrodes do you have?

 

[Rock86]

You stated that there is no water pipe electrode or building steel electrode so besides the ground rods what electrodes do you have?

Only rods. The new rods we need to install will be at different location.

Existing grounding rods, and new.

 

[infinity]

Only rods. The new rods we need to install will be at different location.

Existing grounding rods, and new.

Are these rods all serving the same structure? If so then they must be connected together.

 

[augie47]

Also note 250.121 with provisions to use an EGC as a GEC

 

[Rock86]

I'm questioning the install now. I don't like the idea of a GEC being ran over 300ft to the SDS. The additional ground rods, would be bonded to the GES, and provide a continuous effective ground path.

Thanks for the help, I need scan through the codes again.

 

[infinity]

If this all within one structure you can eliminate the rods at the transformer because you still need to run all the way back the building GES anyway. You cannot install the rods at the transformer location to eliminate a connection to the building GES 300' away.

 

[Rock86]

If this all within one structure you can eliminate the rods at the transformer because you still need to run all the way back the building GES anyway. You cannot install the rods at the transformer location to eliminate a connection to the building GES 300' away.

That it what I am reading. 250.30 spelled that out. I was too concerned about the effective ground path with such a long run.

 

[infinity]

That it what I am reading. 250.30 spelled that out. I was too concerned about the effective ground path with such a long run.

If your thinking of the effective ground path for what is being served by the transformer that relies on the system bonding jumper not the connection to a grounding electrode.

 

[hillbilly1]

I believe it’s still legal to take the new ground rods to building steel if you have that, since the service has its own rods. Or not even drive new rods if you do have building steel that is bonded to the service.

 

[Rock86]

I believe it’s still legal to take the new ground rods to building steel if you have that, since the service has its own rods. Or not even drive new rods if you do have building steel that is bonded to the service.

I dont' have building steel, that is the problem., but thanks. I think Infinity and Augie got me on the right path. I was looking at this all wrong and over complicated the hell out of it.