Ufer Ground questions

[hevnbnd]

Have a house with 400 amp service that comes in to an attached shop. We are coming out of the milbank to two separate 200 Amp panels on each end of the house ( They are about 125' away) and another 200 amp panel in the shop.

The house is using basalt FRP rebar in the footings... So the question comes should I have scrap the FRP rebar in just the shop and have #4 rebar installed in the footings of the shop only and tie to it for a Ufer ground or should I just install the 20' of #4 bare copper in the footing along side the FRP rebar? Would one provide a better ground over the other?

 

[Dennis Alwon]

I am unfamiliar with that rebar but it sounds like it is insulated. If so then you can't use it. Just put 20' #4 copper in the footer and be done

 

[texie]

Have a house with 400 amp service that comes in to an attached shop. We are coming out of the milbank to two separate 200 Amp panels on each end of the house ( They are about 125' away) and another 200 amp panel in the shop.

The house is using basalt FRP rebar in the footings... So the question comes should I have scrap the FRP rebar in just the shop and have #4 rebar installed in the footings of the shop only and tie to it for a Ufer ground or should I just install the 20' of #4 bare copper in the footing along side the FRP rebar? Would one provide a better ground over the other?

If I understand correctly, you have 2 feeders going to the house. That is not compliant.

 

[hevnbnd]

If I understand correctly, you have 2 feeders going to the house. That is not compliant.

You do understand me. The Millbank meter socket is a 320 amp, OH/UG with 2-200amp main breakers in it.

 

[MNSparky]

Basalt rebar isn't conductive so you can't use it as a Ufer. You need at least 20' of uncoated steel rebar in the footing to count as a Ufer. Around these parts, it's on the concrete guy to provide the Ufer stub up for us. If they don't, they are digging up the footing and laying the rebar next to it and pouring over it again. If that's not the case for your area, 20' of bare #4 copper in the footing would do the trick.

 

[hevnbnd]

Basalt rebar isn't conductive so you can't use it as a Ufer. You need at least 20' of uncoated steel rebar in the footing to count as a Ufer. Around these parts, it's on the concrete guy to provide the Ufer stub up for us. If they don't, they are digging up the footing and laying the rebar next to it and pouring over it again. If that's not the case for your area, 20' of bare #4 copper in the footing would do the trick.

Yea I know it isn't conductive... I was really trying to get at if there would be a better ground if in the shop if I just had them use rebar instead of the Basalt Rebar.... Shop is 50 x 22 so there would be a fair amount of rebar going in it. Guess I was not sure if the 20' of bare #4 is as good as using rebar instead.

 

[Dennis Alwon]

If I understand correctly, you have 2 feeders going to the house. That is not compliant.

But the shop is attached to the house, yes? Where is the 400 amp meter?

 

[MNSparky]

You do understand me. The Millbank meter socket is a 320 amp, OH/UG with 2-200amp main breakers in it.

As long as you have the service disconnects grouped as you stated above, you're good to go with those two 200amp sub panels.

 

[hevnbnd]

But the shop is attached to the house, yes? Where is the 400 amp meter?

Yes. The shop is attached to the house sort of... It has a covered carport that attaches to both the house's garages and the shop. The 400 amp meter is attached to the shop.

We are planning on running underground from the Millbank to the two 200Amp panels.

 

[Dennis Alwon]

Yes. The shop is attached to the house sort of... It has a covered carport that attaches to both the house's garages and the shop. The 400 amp meter is attached to the shop.

We are planning on running underground from the Millbank to the two 200Amp panels.

I don't see an issue with that but again the rebar cannot be used as it is insulated.

 

[MNSparky]

Yea I know it isn't conductive... I was really trying to get at if there would be a better ground if in the shop if I just had them use rebar instead of the Basalt Rebar.... Shop is 50 x 22 so there would be a fair amount of rebar going in it. Guess I was not sure if the 20' of bare #4 is as good as using rebar instead.

Copper is more conductive than steel but the steel would give you more surface area of contact to the concrete so I couldn't tell you which one would be better. The code allows either so it's kind of a horse a piece. Do whatever is easier for you.

 

[hevnbnd]

Copper is more conductive than steel but the steel would give you more surface area of contact to the concrete so I couldn't tell you which one would be better. The code allows either so it's kind of a horse a piece. Do whatever is easier for you.

Yea that was my thought. Super easy to do either one.

 

[Dennis Alwon]

Just a bit further on the rebar. Rebar must have 20' exposed in the footing in order for it to be effective. Insulate the rebar and you may as well have used plastic pipe--it will not help.

Informational Note: Concrete installed with insulation, vapor
barriers, films or similar items separating the concrete from the
earth is not considered to be in “direct contact” with the earth.

 

[hevnbnd]

Just a bit further on the rebar. Rebar must have 20' exposed in the footing in order for it to be effective. Insulate the rebar and you may as well have used plastic pipe--it will not help.

Correct. I was thinking that i could have the concrete guys use regular #4 in just the shop that is 22 x 50 size if that helps with a better ground.

 

[infinity]

Correct. I was thinking that i could have the concrete guys use regular #4 in just the shop that is 22 x 50 size if that helps with a better ground.

You only need 20' they could tie wire 2-10' pieces together and you're good.

 

[MNSparky]

You only need 20' they could tie wire 2-10' pieces together and you're good.

If they stub it up, you'd need more than that though unless they are tying it to other uncoated rebar. 20' in the concrete plus whatever length is needed to stub up. The concrete guys always try to bend a 90 in the end of a 20' piece and call it good. When all the other rebar they are tie-wiring it to is epoxy coated or basalt, that's a no-go. I tell them to put 30' in with a stub up. And take a picture of it for the inspector.

 

[Dennis Alwon]

You all are making it too confusing, IMO. Just use 20' #4 copper.

 

[infinity]

If they stub it up, you'd need more than that though unless they are tying it to other uncoated rebar. 20' in the concrete plus whatever length is needed to stub up. The concrete guys always try to bend a 90 in the end of a 20' piece and call it good. When all the other rebar they are tie-wiring it to is epoxy coated or basalt, that's a no-go. I tell them to put 30' in with a stub up. And take a picture of it for the inspector.

Yes if you're using the stub up method you'll need more than 20' of rebar. If you're connecting in the footing then 2-10' pieces tied together will work.

 

[ActionDave]

Correct. I was thinking that i could have the concrete guys use regular #4 in just the shop that is 22 x 50 size if that helps with a better ground.

I agree with Dennis, 20' of 4AWG and be happy.

 

[dinotone]

Basic question on this same topic... (not a big forum user yet, so not sure if this is kosher vs new topic).

Anyway... I'm about to do an ufer ground for first time and leaning toward the 20' of #4 bare solid in the footing. Does this need to be attached to any of the existing rebar? Or just lay in the footing form before pour?

2nd question. If indeed there was already 20' of regular (not FRP) rebar in the footing (ie. not requiring 20' of 4 AWG), what is the recommended way to attach to the #4 solid (in my case) to that rebar? Would a direct burial bronze standard ground rod connector do?