Grounding RING??

[rvim002]

I am designing a grounding system for an industrial site.

I have a room which I plan to have a grounding ring. Because I will be using BARE copper cable, should the ground grid still be a ring?? Can I just not surround three sides of the building with the ground wire and connect to the rebars? ( Because on the fourth side, there is an exisiting structure, and I just didnt want the hassle of digging into the existing structures).

 

[rcarroll]

This is from 250.52(A)(4) "A ground ring encircling the building or structure, in direct contact with the earth, consisting of at least 20' of bare copper conductor not smaller than 2 AWG."
Sounds like you'll be ok.

 

[tom baker]

If you do not encircle the building its not a ground ring. Its a length of copper wire in the ground. As long as you have other grounding electrodes you will be compliant with the NEC.

 

[infinity]

If you do not encircle the building its not a ground ring. Its a length of copper wire in the ground. As long as you have other grounding electrodes you will be compliant with the NEC.

I agree with Tom, the requirement for a ground ring is that it must encircle the building or it does not qualify as an electrode.

 

[dereckbc]

I concur with Tom and Rob. To be compliant with NEC you will have to use a rod or two to comply. Silly I know, but that is the rule IMO.

 

[dereckbc]

This is from 250.52(A)(4) "A ground ring encircling the building or structure, in direct contact with the earth, consisting of at least 20' of bare copper conductor not smaller than 2 AWG."
Sounds like you'll be ok.

RC the keyword here is ENCIRCLING

 

[dereckbc]

Second thought here I Re-read the OP. So I will throw this out for discussion.

If he ties it into the rebar, does that not constitute a UFER or concrete encased electrode therefor no need for a ground rod?

 

[benaround]

How large is the room ? Just courious!!

 

[LarryFine]

Can I just not surround three sides of the building with the ground wire and connect to the rebars? ( Because on the fourth side, there is an exisiting structure, and I just didnt want the hassle of digging into the existing structures).

If you can land the two ends of the new three-side ring onto an existing ring, that should qualify. Is there one now?

I wouldn't do anything without proper engineering. I wouldn't want to make a mistake either way; too much ring or too little.

 

[wirenut1980]

Second thought here I Re-read the OP. So I will throw this out for discussion.

If he ties it into the rebar, does that not constitute a UFER or concrete encased electrode therefor no need for a ground rod?

I agree. It sounds like he can tie to the rebar of the building's foundation, and get himself an approved grounding electrode, so no need for a ground ring or ground rods. Of course the UFER must meet 250.52(A)(3).

 

[rcarroll]

RC the keyword here is ENCIRCLING

I agree. It's a wierdly written statement to me. How small can a building be for a minimum of 20' to encircle the building? When the OP said that the "ground ring" would also connect to the rebar, I figured it's ok.

 

[dereckbc]

How small can a building be for a minimum of 20' to encircle the building?

An Out House maybe?

When the OP said that the "ground ring" would also connect to the rebar, I figured it's ok.

I still think if the ring is connected to the rebar satisfies the requirement even though technically it is not a ring. It is a concrete encased electrode with a radial.

 

[rcarroll]

Agreed. Thanks for the info.:smile:

 

[raider1]

How small can a building be for a minimum of 20' to encircle the building?

Keep in mind that 250.52(A)(4) says encircling the building or structure. A pole is a structure.

Chris