TNE Letters to the Director: SOLAR CABLES

SOLAR CABLES.

Question:

Solar cables according to CEI 20-91 have a nominal voltage of 0.9/1.5 kV in direct current and are suitable for photovoltaic systems up to a voltage of 900V to ground (voltage at the lowest expected temperature), TNE 5/10, page 20. Can the same cable be considered as Class II up to 675V, according to guide blue no. 15, table 9.B?

Answer:

A cable with insulation suitable for the served electrical system and installed in an insulating protective conduit constitutes a Class II conduit, CEI 64-8, art. 413.2.4.

The same article considers Class II conduits up to 690V (without specifying whether in AC or DC). In the most permissive interpretation of the standard, Class II in direct current is applicable up to the voltage

1.5x690 V = 1035 V DC