lightning rod connections to ground rods

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duckhead

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Windsor, SC
Hi all, I have 38 years as an electrician and contractor combined, but only a few times did I have anything to do with lightning protection. A couple of months ago, I disconnected 4 lightning protection cables going to 4 rods at corners of a removable metal building which covers a 200 hp pump/motor and controls. The building was removed to pull pump and motor for servicing. There is a short pigtail attached to each ground rod for connection to cables coming from lightning rods. I noticed when I disconnected, that the cable clamps were loosely connected. My question is: should cable from lightning rods on top of building to ground rods be loosely or tightly connected? Your help would be greatly appreciated.
 
ron said:
Tight. Low impedance path is needed
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On the other hand there is more than enough voltage to jump a gap that would provide an open connection a line voltages.
You want to encourage the lightning as much as possible to follow the desired path rather than alternate paths, but inductive factors like small diameter wires, sharp bends and long runs of wire are probably much more of a concern than loose connections.

If it is loose enough to eventually vibrate and fall off, that is big concern.
 
Those ground rods have "pigtails" attached to them. The lightning conductor should be cadwelded to those pigtails. I strongly advise looking over NFPA 780 " Standard For the Installation of Lightning Protection Systems" and UL 96A "Installation Requirements for Lightning Protection Systems"
 
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