I've wired several gasoline dispensing stations in my time and always used PVC conduit utilizing 514.8 Exception 2.

The organization I work for now is updating its fuel dispensing system. One of the reasons is becasue the GRS conduit used in the last few feet has rusted out. (The rest of the system is in PVC) The winning contractor said he was required to use rigid steel conduit throughout the system for warranty purposes. The companys making the demand are Fuel Master and Bennett Pumps. I pointed out my past experience with PVC and told the contractor I would research the information.

Both FM and Bennett Pumps stated originally PVC was okay as long as I understood an "Act of God" (Lightning is considered an Act of God) would void the warranty. The contractor then contacted the companies and the next thing I knew... I received retractions from FM and Bennett Pumps stating the system most use GRS throughout.

Their installations instructions advise that if there is a reason GRS cannot be used... contact them for a workaround. So I called them back. I was told it was okay to use PVC coated GRS for the system. I have a hard time understanding this.

The reason they first cited for using GRS was to dissapte any lightning induced surges to ground through the walls of the GRS and that PVC wouldn't allow that. So I asked how PVC coated GRS would be any better than PVC. I received no answer.

We now have a very expensive PVC coated GRS conduit system in place. I keep trying to get an answer from FM and Bennett Pumps... becasue I would like to know the technical reasoning behind their decision.

Have any of you ran into this issue? Does anyone know the reasoning behind PVC coated GRS as opposed to PVC conduit? Any technical explanation would be appreciated... or any agreement with me would help me not feel so foolish. Any opinions?