Seems to me that the best practice for TL inverters is to use double-insulated conductors from the array string(s) to the combiner (if used) to the inverter.
That said, there doesn't appear to be any written requirement in the NEC to use double-jacketed conductors. So as long at the conductor is duly listed as "PV wire," it's OK to use in DC circuits with TL inverters. marco HI Marco I think there has been a lot of bad/old information about PV vs double insulated wire. However now it only listed as PV wire. 690.35 D (3) jay peltz power On Oct 23, 2014, at 2:29 PM, Marco Mangelsdorf wrote: Yet again this "PV wire" thing rears its head. For our PV systems using transformerless (TL) inverters, our standard practice has been to use double-insulated conductors for all DC circuits coming into the TL inverter(s), which we believe represents the best practice. However, there doesn't appear to be any requirement stated in the code that states the need to use double-insulated conductors for DC circuits and TL inverters. So I'm thinking, why pay the extra expense for the double-insulated wire when single-insulated wire may suffice. Anyone know of anything written somewhere that requires the use of double-insulated conductors in TL DC circuits? Thanks, marco
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