Grounding electrode conductor in the same raceway as transformer feeders?

[Kevinsee]

When installing a transformer can you pull in the grounding electrode conductor in the same raceway as the feeder conductors for the transformer?

-The equipment grounding conductors sized accordingly for the transformer feed.
-The grounding electrode conductor coming off MDP main buss that is the location of grounding electrode and location of the main bonding jumper.
-If its done properly with bonding bushing on each end of the emt raceway and bonding in any pull cans ect.

I would like some feed back. I haven’t seen this done, so i could be missing a reason why you cant.

 

[kwired]

I see it redundant to run both that GEC and an EGC, use which ever table requires a larger conductor. Step up vs step down transformer can change which needs to be larger

 

[infinity]

The grounding electrode conductor coming off MDP main buss that is the location of grounding electrode and location of the main bonding jumper.

Is it permitted to land the transformer GEC on that bus?

 

[kwired]

Is it permitted to land the transformer GEC on that bus?

Seems like a great place when there is no structural steel, no metal water piping and the only electrode present is a ground rod(s) or a CEE.

 

[jaggedben]

See 250.121. Assuming you're not required to terminate your GEC closer (see infinity's post) then it's allowed only by the exception. That is, it's allowed provided you follow the requirements for both, and the more stringent requirements are for GECs. Bond at both ends, irreversible splices, etc.

 

[don_resqcapt19]

Seems like a great place when there is no structural steel, no metal water piping and the only electrode present is a ground rod(s) or a CEE.

It does, but there is no provision in the code that I am aware of that permits that connection point. If the GEC does not directly connect to an electrode, the only other places it can connect are in 250.68(A) and the bus in the service equipment is not one of those places.

The only thing that is close to permitting the installation proposed in this post would be 250.64(D)(1)(3), but unlikely that the bus complies with that section.

Probably a good place for a 2026 PI to make a change.

 

[jaggedben]

It does, but there is no provision in the code that I am aware of that permits that connection point. If the GEC does not directly connect to an electrode, the only other places it can connect are in 250.68(A) and the bus in the service equipment is not one of those places.

The only thing that is close to permitting the installation proposed in this post would be 250.64(D)(1)(3), but unlikely that the bus complies with that section.

Probably a good place for a 2026 PI to make a change.

If there are multiple SDS then 250.30(A)(6)(c)(2) permits the GECs to be tapped from a busbar.

 

[jaggedben]

See also the exceptions to 250.30(A)(5). Kinda inscrutable but may allow it.

 

[jaggedben]

And finally, note that 250.30(A)(4) was revised in the 2017 NEC to no longer require the GEC to go to the closest water pipe or structural steel. In fact it now requires connection to the building GES which seems to be what the OP is proposing.

 

[don_resqcapt19]

If there are multiple SDS then 250.30(A)(6)(c)(2) permits the GECs to be tapped from a busbar.

Very unlikely the bus in the gear complies with that requirement.

... Listed connections to aluminum or copper busbars not smaller than 6 mm thick × 50 mm wide (1⁄4 in. thick × 2 in. wide) ...

 

[don_resqcapt19]

And finally, note that 250.30(A)(4) was revised in the 2017 NEC to no longer require the GEC to go to the closest water pipe or structural steel. In fact it now requires connection to the building GES which seems to be what the OP is proposing.

That does not change the requirement that the GEC for the SDS connects to the electrode itself. The OP is proposing a connection to a grounding bus in the service equipment and that is not a connection to an electrode.

 

[tom baker]

And the GEC must be unspliced (exceptions for compression spliced, busbars)

 

[wwhitney]

See also the exceptions to 250.30(A)(5). Kinda inscrutable but may allow it.

(2017) 250.30(A)(5) Exception (2) seems to fairly clearly and explicitly allow what the OP proposes.

Cheers, Wayne

 

[jaggedben]

Very unlikely the bus in the gear complies with that requirement.

True, for some reason I was picturing a separate bar, not the one in the MDP.

But he could irreversibly tap to the main GEC in or extend his GEC to the electrode once it gets to the MDP.

 

[Kevinsee]

True, for some reason I was picturing a separate bar, not the one in the MDP.

But he could irreversibly tap to the main GEC in or extend his GEC to the electrode once it gets to the MDP.

The MDP has a few locations in the gear to terminate the GEC. It is 4 sections long 3000 amp service.

 

[jaggedben]

The MDP has a few locations in the gear to terminate the GEC. It is 4 sections long 3000 amp service.

Does the ground bar meet the requirements Don mentioned in post #10?

 

[Kevinsee]

A little more back ground. Square D outdoor service.

Sprinkle bond - 250 Al
Ufer 4# Cu
Telecom bond 6# cu
Gas bond 1# Al

All landed on copper bus bar that meets nec code

From this copper plate we ran 250 Al back to our MDP to connect our GEC and main bonding jumper at manufacturers provided bar / bussing that runs the length of the MDP.

All this passed inspection no problem.

We ended up having a elevator that needed a to have the voltage stepped up on the second level. No building steel, no ground rounds available being on the second floor, no metal water piping in the area ect.

Our plan is to come from MDP at ground level exterior of building, pipe pvc raceway up to second story, once inside switched over to emt and pipe to the transformer. Grounding Bushing at the end of the raceway at the transformer. Bringing GEC from from MDP main bus bar where our , main bonding jumper and other GEC connection is done.

Any reason you cant run the GEC in the raceway with the transformer feeders and its egc?

 

[Kevinsee]

Does the ground bar meet the requirements Don mentioned in post #10?

The

That does not change the requirement that the GEC for the SDS connects to the electrode itself. The OP is proposing a connection to a grounding bus in the service equipment and that is not a connection to an electrode.

250.30 (4) says must be grounded to the building grounding electrode system. The bar in the MDP is part of the system’s so this shouldn’t be a problem

 

[Kevinsee]

Does the ground bar meet the requirements Don mentioned in post #10?

Yes the bussing in the MDP is 1/4 thick and 2” wide.

 

[kwired]

A little more back ground. Square D outdoor service.

Sprinkle bond - 250 Al
Ufer 4# Cu
Telecom bond 6# cu
Gas bond 1# Al

All landed on copper bus bar that meets nec code

From this copper plate we ran 250 Al back to our MDP to connect our GEC and main bonding jumper at manufacturers provided bar / bussing that runs the length of the MDP.

All this passed inspection no problem.

We ended up having a elevator that needed a to have the voltage stepped up on the second level. No building steel, no ground rounds available being on the second floor, no metal water piping in the area ect.

Our plan is to come from MDP at ground level exterior of building, pipe pvc raceway up to second story, once inside switched over to emt and pipe to the transformer. Grounding Bushing at the end of the raceway at the transformer. Bringing GEC from from MDP main bus bar where our , main bonding jumper and other GEC connection is done.

Any reason you cant run the GEC in the raceway with the transformer feeders and its egc?

I don't think there is any reason you can't. The question seems to have turned into where can you connect it?