I'm looking for a little input from someone who has experience performing grounding system testing.
If you were asked to perform standard NETA maintenance testing on the grounding system at a large building on a relatively tight site, such as the one pictured here, how would you go about it? Let's assume there is a ground ring around the entire building.
To measure the electrode-to-ground resistance, it would seem problematic to use the standard fall-of-potential method because of the large test probe spacing required. Assuming the ground ring runs around the entire building, the max dimension of the electrode system would be about 750' which would require the current probe to be placed well beyond 1000' using the standard FOP method. Even using the Slope Method (Intersecting Curves Method) would require the current probe to be placed over 1000' away which is infeasible.
The only good alternative I can think of is using a clamp on ground tester at the service point. The particular site used as an example here has an underground medium-voltage feed from the utility that serves the customer's MV switchgear lineup. I'm thinking we can make appropriate use of a clamp on meter if we measure at the point that the concentric neutrals combine and connect to the ground bar. Would you consider this to be an acceptable way of measuring the electrode system resistance?
Any thoughts?
If you were asked to perform standard NETA maintenance testing on the grounding system at a large building on a relatively tight site, such as the one pictured here, how would you go about it? Let's assume there is a ground ring around the entire building.
To measure the electrode-to-ground resistance, it would seem problematic to use the standard fall-of-potential method because of the large test probe spacing required. Assuming the ground ring runs around the entire building, the max dimension of the electrode system would be about 750' which would require the current probe to be placed well beyond 1000' using the standard FOP method. Even using the Slope Method (Intersecting Curves Method) would require the current probe to be placed over 1000' away which is infeasible.
The only good alternative I can think of is using a clamp on ground tester at the service point. The particular site used as an example here has an underground medium-voltage feed from the utility that serves the customer's MV switchgear lineup. I'm thinking we can make appropriate use of a clamp on meter if we measure at the point that the concentric neutrals combine and connect to the ground bar. Would you consider this to be an acceptable way of measuring the electrode system resistance?
Any thoughts?
