Redundant GEC to sub-panel allowed?

[LarryFine]

New installation, old building: Existing outside metering, trough, two fused switches. I'm installing feeders in new EMT to two new inside panels.

They already included unnecessary EGCs in the feeders in the plans, despite my advice, and they bought the wire, so I'm going to install them.

The plans also include a GEC from each interior panel to the water pipe, which I explained shouldn't be in the plans or installed in the building.

My question is whether such redundant GECs are permitted? If so, can they tap onto the main GEC as usual, i.e., with split bolts, for example?

Would there be any sizing issues with what would effectively be placing EGCs and GECs sized for each panel in parallel with the main GEC?

 

[Little Bill]

I don't think a conductor from the subpanel to a water pipe would be considered a GEC, it would be a bonding jumper if anything.

 

[texie]

I'm not aware of anything that would prohibit such a thing as long as it was connected only to the EGC of the sub panel. I would be inclined not to do it though as it will just serve to confuse others.

 

[LarryFine]

The customer is concerned because:

"My conversation with (first reviewer of the permit and drawings now retired) clearly indicated that if we didn't run GECs to the cold water main, we wouldn't get approved. "

 

[synchro]

So the service disconnect would have a GEC connection to the water pipe system and the subpanels would also, but they would be connected to the pipe at more than one place? If so then that would place the EGCs and the water pipe in parallel for some distance. I don't think that would be good because the water pipes could then conduct ground fault currents.

 

[LarryFine]

So the service disconnect would have a GEC connection to the water pipe system and the subpanels would also, but they would be connected to the pipe at more than one place?

No. Standard GEC from neutral in trough below switches will be run to new 2" incoming water line.

The plans show an additional GEC from each panel to the water line, too.

 

[LarryFine]

I just looked at the plans again. First of all, they show an existing GEC from the trough to the water line, but it was removed when the building interior was gutted. We included replacing it in our discussions and in my proposal.

Above the trough are two fused switches. The conduits leaving the switches will run inside about 30 to 40 feet and terminate in a pair of main-breaker panels, and will also contain the previously-mentioned EGCs I agreed to install.

The plans also show a new GEC from each panel, also labeled to be run to the water line. My opinion is that they should be entirely omitted, but the customer's is that they should be done just because they're in the plans.

They may be thinking the inside breakers are the service disconnects, and where GECs should land. If they were, the old GEC wouldn't need to be replaced, and there would be no need for the redundant EGCs in the feeder.

 

[oldsparky52]

Who drew the plans?

 

[infinity]

The plans also show a new GEC from each panel, also labeled to be run to the water line. My opinion is that they should be entirely omitted, but the customer's is that they should be done just because they're in the plans.

There is nothing that would prohibit doing this which seems to be your question. IMO you cannot "over-ground" an installation and are not prohibited from doing so.

 

[LarryFine]

My question is whether such redundant GECs are permitted? If so, can they tap onto the main GEC as usual, i.e., with split bolts, for example?

Would there be any sizing issues with what would effectively be placing EGCs and GECs sized for each panel in parallel with the main GEC?

 

[winnie]

There is nothing that would prohibit doing this which seems to be your question. IMO you cannot "over-ground" an installation an are not prohibited from doing so.

Imagine that this were a steel structure with the pipes and panels attached to the steel.

There would be numerous parallel paths between the electrical EGC system and the metal piping system, and this would be totally fine.

IMHO parallel paths in metal not intended to carry current (EGC, building framing, conduit, pipe, etc.) is fine.

The counter argument would be if you were intentionally designing the grounded metal circuit paths to control things such as lightning current flow, or for precision electromagnetic measurements, where you might be enforcing a particular bonding topology.

Jon

 

[xformer]

New installation, old building: Existing outside metering, trough, two fused switches. I'm installing feeders in new EMT to two new inside panels.

They already included unnecessary EGCs in the feeders in the plans, despite my advice, and they bought the wire, so I'm going to install them.

The plans also include a GEC from each interior panel to the water pipe, which I explained shouldn't be in the plans or installed in the building.

My question is whether such redundant GECs are permitted? If so, can they tap onto the main GEC as usual, i.e., with split bolts, for example?

Would there be any sizing issues with what would effectively be placing EGCs and GECs sized for each panel in parallel with the main GEC?

IMHO... This just creates a low impedance current sink, before going to the main EGC.

 

[infinity]

Imagine that this were a steel structure with the pipes and panels attached to the steel.

There would be numerous parallel paths between the electrical EGC system and the metal piping system, and this would be totally fine.

IMHO parallel paths in metal not intended to carry current (EGC, building framing, conduit, pipe, etc.) is fine.

Jon

Yes in structural steel buildings everything is connected together. There are thousands of parallel paths for the metal components. Whether done intentionally or not there is no issue.

 

[Cow]

If they're paying for it and you can't talk them out of it and it's legal.............

 

[hillbilly1]

I had an inspector want the existing ufer ground taken out to the new service rated transferswitch, we already had all the required grounding electrodes out there, and we moved the existing ufer to the ground bar at the old service. The new service was 50’ away from the building, so it wasn’t practical to re-use it. I told him if I cut it off at the slab, it was no longer a ufer, so he decided just leave it where it was. LOL!

 

[LarryFine]

Well, the work is done, redundant jumper and all. I used a single split bolt for the single #4, up from one panel and down to the other one. You can just see it at the top of the double stud in the second pic.