I have a new 300 kVA, 12.47kVwye - 480Vwye service transformer for a petroleum distribution facility that has existing cathodic protection system on underground pipelines. Local inspector has given verbal approval to use a cathodic isolation (PCR)module between neutral & grnd of service entrance to satisfy 250-6(e)and block the injected DC. Any special concerns for ground grid under pad mounted transformer or under the service entrance building (14' x 8') less than 10 ft. away?
Thanks!

Cathodic protection is its own beast so far a NEC-type systems are involved. Is it safe to assume that the 300kVA transformer is under the domain of the petrochem and not an electric utility? You might start by scrutinizing the listing instructions and, as needed, contact the “PCR-module” manufacturer for resolution. If this is new territory for the inspection authority, he may be easiest to work with if you approach him up front with as much PCR-specific application information as possible.




[This message has been edited by Bjarney (edited 05-04-2004).]

BJarney - Thanks! I have an inquiry in to the PCR manufacturer regarding grounding concerns and have provided a data package to the inspector. I was hoping to link up with someone else who had worked with the nuts and bolts of this sort of installation.

rapahoe — I didn’t mean to lead you astray and pretend I was any sort of CP whiz. I’ve found the “Leister golfcart battery chargers” in rural areas and see them indicating ~50 amperes DC disappearing into the ground over a set of mysterious cables.

One author of CP-application papers is John P Nelson in Colorado, with some online PDFs available at www.neiengineering.com/papers/papers.html

Bjarney, Thanks for the link to John's web site. I had the priviledge of meeting him in Denver a couple years ago.

[I’m not sure I would recognize a ‘Little FINK’ test station if I tripped over it.]