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Cable and connector voltage ratings for photovoltaic (PV) installations

Designers and installers of PV installations need to ensure cables and cable connectors being used in the PV installation will be operating within voltage ratings specified by the manufacturer. This is so the cables and connectors will not be electrically stressed and breakdown through exposure to voltages higher than they are designed for.

PV cables and connectors must have the following ratings to operate safely under normal conditions, and to withstand the full array voltage across the cables and connectors in the event of an earth fault;

  • a DC conductor to earth voltage rating that is greater than the maximum open circuit array voltage
  • a DC conductor to conductor voltage rating between positive and negative cables that is greater than the maximum open circuit array voltage.

Designers and installers need to be aware of the DC ratings of a cable, and that they can be different to the AC ratings for the cable.

Cable voltage ratings are specified in the format of Uo/U where Uo is the voltage rating conductor to earth and U is the voltage rating conductor to conductor. The Uo/U rating should also indicate if it relates to AC or DC. Some examples of cable manufacturers’ methods to specify rating include:

  • 0.6/1kV AC, 900/1.5kV DC
    • this indicates a 600V conductor to earth AC voltage rating and a 1000V conductor to conductor AC voltage rating; and
    • a 900V conductor to earth DC voltage rating and a 1500V conductor to conductor DC voltage rating.
  • AC 600/1000V, DC 900/1800V
    • this indicates a 600V conductor to earth AC voltage rating and a 1000V conductor to conductor AC voltage rating; and
    • a 900V conductor to earth DC voltage rating and a 1800V conductor to conductor DC voltage rating.

PV domestic installations installed in accordance with AS/NZS 5033 Installation and safety requirements for photovoltaic (PV) arrays cannot exceed 600V DC maximum open circuit array voltage. This means for a domestic installation this is the maximum DC voltage a conductor in this situation will be exposed to. AS/NZS 5033 quotes several cable standards that satisfy this voltage requirement, including TUV PV1-F; UL 4703; or VDE-AR-E 2283-4.

Large scale solar farms and some commercial installations may have a maximum open circuit array voltage rating that is higher than the voltages of domestic installations and may exceed the 900V DC conductor to earth rating typically quoted by cable manufacturers (i.e. cables tested to TUV PV1-F; UL 4703; or VDE-AR-E 2283-4 may not be adequate).

Important Note: Installation of cables where the maximum open circuit array voltage rating is above the typically quoted 900V DC conductor to earth rating of cables needs careful consideration. If the cable voltage rating is not adequate this may require additional engineering processes, or replacement of cable with suitable voltage ratings, to ensure the cable installed can safely withstand the voltage levels from possible earth faults on the system.

Further information

For more information on solar photovoltaic (PV) systems, visit www.worksafe.qld.gov.au

Last updated
19 April 2018

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