We are looking to install a transformer fire barrier between two of our main incoming transformers (34.5 KV to 13.8V) at our substation that feed power to our facility. The fire barrier will be of a concrete masonry unit (CMU) type. There is a single containment for these two transformers and there is a cable tray that runs between the two transformers for protective relay controls. As a result of the tight distances between the transformers and the cable tray, the fire barrier (CMU) will be within 4 feet of the high voltage cables (34.5KV,13.8KV). The CMU will be grounded to the ground grid. The concern we have is that there is not enough distance between the barrier and the overhead transformer power lines and could cause an issue with there being a conductive path from the transformer lines through the fire barrier. Does anyone have any experience with this application and insight into if this setup is approved/allowed within NFPA70 and NFPA850 code?
