masterelect1
Senior Member
- Location
- Baltimore
The buildings (3) that I am currently inspecting have the following set-up for a grounding/lightning protection system; a ground rod driven at each of the three main power panelboards and connected as required to the proper size grounding conductor and interconnected to a ground ring which encircles each building. Each ground ring is interconnected and the entire system is connected multiple times to building steel and driven ground rods. Additionally, the rooftop air terminals are connected to the ground ring.
Here is my issue: as per NEC 250:53F, the ground ring is to be buried at a minimum depth of 30". It is nowhere near this depth; 20" would be the maximum at any point in the system.
I received a response from the designer which stated that the ground rods driven at each of the 3 distribution panels are sufficient and that the ground ring only needs to be at a depth of 18" (?) as it is only being used for a lightming arresting system.
My concern is that because the ground ring (at less than 30") and the rods at each of the 3 panels are tied together through building steel the entire grounding system has been compromised.
Thanks in advance,
John
Here is my issue: as per NEC 250:53F, the ground ring is to be buried at a minimum depth of 30". It is nowhere near this depth; 20" would be the maximum at any point in the system.
I received a response from the designer which stated that the ground rods driven at each of the 3 distribution panels are sufficient and that the ground ring only needs to be at a depth of 18" (?) as it is only being used for a lightming arresting system.
My concern is that because the ground ring (at less than 30") and the rods at each of the 3 panels are tied together through building steel the entire grounding system has been compromised.
Thanks in advance,
John