It has to do with the development of a “double-insulated” conductor needed for ungrounded systems. PV Wire is double-insulated while USE-2 is not tested as double insulated. It is analogous to double-insulated tools in the U.S. that do not require a ground wire.
Bill. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Marco Mangelsdorf Sent: Friday, October 01, 2010 11:09 AM To: 'RE-wrenches' Subject: [RE-wrenches] Tranformless inverter Bill B. wrote the following: Ungrounding the array requires additional fusing and disconnects, but the most significant difference is that the module wiring and all external cable must be PV Wire/Cable. Therefore only modules with PV Wire/Cable can be used in these systems. You must confirm from the manufacturer that they have made the switch. Hopefully all manufacturers will be installing PV Wire/Cable soon so that this will not be a problem anymore. --My question: why is the standard USE-2 wire not acceptable any mo’? marco
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