Ground Ring for Lightning Protection System

[faresos]

Hello Everyone:

I'm working on an existing building that is over 60ft. The client wants to add a lightning protection system to this existing building. Per NFPA 780, a ground ring is required since the structure is over 60ft. I'm not sure how feasible it is to install a ground ring since we have a side walks all around the building. Is there any exception for not install a ground ring and can just do with ground rods? another question, what is the maximum spacing between ground rods needed around the building? Can we just install one at each corner (4 corners) even though this is a large building?

Thanks,

 

[topgone]

Did you mean "60 feet or less"?

 

[faresos]

Did you mean "60 feet or less"?

exceeding 60 ft per NFPA 780

4.14.2* For structures exceeding 60 ft (18 m) in height, the
interconnection of the lightning protection system grounding
electrodes and other grounded media shall be in the form of a
ground loop conductor.

 

[topgone]

exceeding 60 ft per NFPA 780

4.14.2* For structures exceeding 60 ft (18 m) in height, the
interconnection of the lightning protection system grounding
electrodes and other grounded media shall be in the form of a
ground loop conductor.

The code permits using a "ground ring" to act as "ground rods". Try reading 250.50 (NFPA 70).

"250.50 Grounding Electrode System. All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used.
Exception: Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding electrode system where the steel reinforcing bars or rods are not accessible for use without disturbing the concrete.

Take note of the provisions of 250.52(A)(1) through (A)(7). The intent of the code is that the ground ring follows the contour of the building. Hope that helps.

 

[Gary11734]

Hello Everyone:

I'm working on an existing building that is over 60ft. The client wants to add a lightning protection system to this existing building. Per NFPA 780, a ground ring is required since the structure is over 60ft. I'm not sure how feasible it is to install a ground ring since we have a side walks all around the building. Is there any exception for not install a ground ring and can just do with ground rods? another question, what is the maximum spacing between ground rods needed around the building? Can we just install one at each corner (4 corners) even though this is a large building?

Thanks,

Doing a 14 story and it has lighting protection. Subbing it out but the drawings don't show a ring around the building.... Bringing two 1" PVC to the roof at each end. The grounding is on each side. No ring around the building. It's a Disney Hotel so they are definitely code compliant and UL listed application. Over 60'