electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I have been cogitating on the idea of an inexpensive step up step down transmission scheme for long wire runs. The idea would be that you would have a 240V source/service, step up to 2KV for the run, and then go back down with a center tapped 120/240 to serve the load. With the advent of 2 KV PV wire, this seems like a potentially very inexpensive option. #12 Cu at 2KV could handle a typical house or cabin up to 3/4 of a mile, and at about 15 cents per conductor (you would need two) vs $2/ft for 15kv primary cable, as well as the very small associated conduit, it is an attractive option when confronted with a long run and/or high cost utility connection. For runs requiring more capacity or longer distances, PV wire is available in larger sizes and aluminum also. The PV wire I have used is also rated RHH-2 and direct bury. I would like to avoid any MV gear if possible, but I am uncertain if there is a way around transformer protection requirements. 240.21(C)(1) could be used to cover the 2KV transformer secondary conductors, and one would think that same philosophy could be used for the transformer protection of the step down transformer. but I do not see any specific permission in 450.3 for this. If there is not any way around this, it seems that there would have to be a 2KV rated OCPD ahead of the step down transformer. The other issue is 490.22, and I am unclear if the disconnect ahead of the step up could meet this requirement. Looking for some opinions or ideas, and of course any other issues that I may not have thought of.