Sub-Panel Ground bus connections?

[ArcticGabe]

My electricians installed a sub-panel in my new garage. The new panel has 2 ground bus bars. One of them they connected to the ground wire that was run from the main panel. The other ground bus was connected to the new ground rod that was installed outside of the garage when they installed the panel.

Am I supposed to connect these two ground buses inside the new panel? If not, which one am I supposed to connect the new circuits to?

Thanks.

 

[wyliesdiesels]

My electricians installed a sub-panel in my new garage. The new panel has 2 ground bus bars. One of them they connected to the ground wire that was run from the main panel. The other ground bus was connected to the new ground rod that was installed outside of the garage when they installed the panel.

Am I supposed to connect these two ground buses inside the new panel? If not, which one am I supposed to connect the new circuits to?

Thanks.

nope you dont need to tie them together. the screws and enclosure do that. you can use both bars for ground wires

Is this garage attached or detached? Im assuming detached since they put in ground rods.

If detached then they shouldve used an insulated ground wire for the feeder. Maybe they just stripped more of the jacket off than is required?

 

[ArcticGabe]

Thanks for the quick reply! And now that you mention it, it makes perfect sense! I just didn't think if that myself...

Yes, it's detached. But the feeder from the house has a bare ground the whole way. Why would it matter since it is run in conduit the whole way? Mr. inspector didn't seem to care (or maybe not know...).

 

[wyliesdiesels]

Underground conduits always fill up with water. The bare copper will corrode and eventually fail.

 

[exranger06]

Underground conduits always fill up with water. The bare copper will corrode and eventually fail.

Then why is it ok to use bare copper for the ground rod?

 

[jeepxj]

Then why is it ok to use bare copper for the ground rod?

do you live in a lake?

 

[pattenp]

Then why is it ok to use bare copper for the ground rod?

It's ok to use bare copper for the EGC in the conduit but it's better for it to be insulated to protect from moisture for long life. The ground electrode conductor is a totally different animal and is not for clearing fault current.

 

[grounded-b]

Underground conduits always fill up with water. The bare copper will corrode and eventually fail.

Copper which is exposed to water, will oxidize. This oxidation will form the green patina we have all seen. This coating actually protects it from further oxidation. That is why copper makes great rain gutters, flashing and roofing material.

It will not fail, from being continuosly exposed to water.

Steve

 

[teamextreme]

I've always known pools/spas had the insulated ground requirement, but I don't think I've ever heard of this for a detached structure. I guess it's not so much a detached structure rule as it is anything run underground. Since romex isn't allowed underground, that means you pretty much always comply with this if you don't run romex, I guess. Which begs the question, what kind of wire did OP's electricians run if it's bare all the way? Sounds like maybe some form of "romex"?

 

[exranger06]

It's ok to use bare copper for the EGC in the conduit but it's better for it to be insulated to protect from moisture for long life. The ground electrode conductor is a totally different animal and is not for clearing fault current.

I know that the ground electrode isn't for clearing fault current, and I never said that it was. But it is a bare copper wire used outdoors, buried underground, and not even in conduit. So if bare copper corrodes so easily in those conditions, why is it ok to use bare copper for the ground rod, but not for an EGC?

 

[exranger06]

do you live in a lake?

Metals corrode just as much in wet soil as they do in actual water.

 

[jeepxj]

Metals corrode just as much in wet soil as they do in actual water.

sure.

and wet soil drains off vs conduit making it a bathtub. unless of course you live in a lake. then it doesn't drain off.

 

[ArcticGabe]

I've always known pools/spas had the insulated ground requirement, but I don't think I've ever heard of this for a detached structure. I guess it's not so much a detached structure rule as it is anything run underground. Since romex isn't allowed underground, that means you pretty much always comply with this if you don't run romex, I guess. Which begs the question, what kind of wire did OP's electricians run if it's bare all the way? Sounds like maybe some form of "romex"?

The electricians ran 2 ga aluminum THWN (2 hots and a neutral) and then a bare copper ground for a 90 amp service. The copper ground from the house looks like about 6 ga or maybe 4 (just guessing based on looks) but it's slightly smaller than the current carrying conductors.

Sounds to me based on the discussion here that running insulated grounds underground is best practice, but not required by code. Is this accurate?

Come to think about it, the ground ran to my garage at my old house also had a bare ground in conduit underground with no quibble from the sparky police.

 

[wyliesdiesels]

yeah not required by code but not a good practice either.

 

[Rbeall]

Does anyone have copper water pipes in their home that has corroded away?��

 

[rlitman]

Does anyone have copper water pipes in their home that has corroded away?��

That's a surprisingly common occurance.

Then why is it ok to use bare copper for the ground rod?

The ground rod itself obviously needs to have electrical contact with the ground. The wire leading to it is solid and not stranded, because smaller strands have more surface area for corrosion.