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PV d.c. isolator installation

Industry guidance

This guidance is intended to assist industry with the installation of PV d.c. isolators. It is in addition to the requirements of AS/NZS 3000, AS/NZS 5033 and all other applicable standards.

Note: this document uses the term d.c. isolator for simplicity and has been used to describe a load break switch disconnector device.

General

To reduce water ingress and premature failure of the d.c. isolator, minimum installation safety requirements must be met in accordance with AS/NZS 5033:2014 4.4.4.6 (a) – (h) including:

  • Strain relief provided for conductors (where conduit is not used to enter the enclosure)
  • Maintaining IP66 Ratings of the d.c. isolator, only manufacturers entry points to be used.
  • Where outdoors, top entries to enclosures shall not be used.
  • Sealing or gluing of conduit glands and adapters.
  • Where entry is via a cable gland, IP rated glands and multi-hole grommets to suit the number of conductors entering shall be used
  • Use of silicon to seal enclosures is not permitted, unless specified by the manufacturer
  • Only manufacturer mounting points shall be used.
  • Anti-condensation valves shall be used where condensation issues exist AS/NZS 3000:2018 Cl. 1.7.2

Terminations

  • Ensure terminals are tightened to manufacturer’s requirements; this includes terminals for bridging links.
  • Do not assume the manufacturer has tightened bridging link terminals.
  • Ensure termination of multistranded cable correctly retains the stranded conductors (see AS/NZS 3000 cl. 3.7.2.5).

ESV recommends using d.c. isolators that have external mounting points

PV d.c. isolator for inverter isolation

AS/NZS 5033 Cl 4.4.1.2 outlines the three methods of inverter isolation. These are:

  • An adjacent and physically separate d.c. isolator
  • A d.c. isolator that is mechanically interlocked with a replaceable module of the inverter
  • A d.c. isolator located in the same external enclosure as the other components of the inverter. With the d.c. isolator in the off position there shall be no risk of electrical hazards when any inverter external cover is removed.

ESV strongly recommends using inverters that contain an integrated d.c. isolator.

Guidance for integrated d.c. isolators

For an inverter which has an integrated d.c. isolator, the integrated d.c. isolator must be registered as a level 3 product on the National Equipment Registration System as integrated into the specific inverter (See EESS Information Bulletin #20-018 for more information).

AS/NZS 5033 has an additional requirement that with the integrated d.c. isolator in the OFF position there shall be no risk of electrical hazards when the cover is removed, and there is separate screening from touch of live parts of the PV array side of the d.c. isolator when the external cover is removed.

AS/NZS 5033 also has additional requirements in clause 4.3.5.2 (a) – (k). This includes the requirement for the integrated d.c. isolator being capable of being secured in the OFF position.

Where the above requirements are met ESV deems this compliant to the standard and does not require an additional d.c. isolator to be installed adjacent to the inverter.

Note: the manufacturer of the inverter should provide a ‘Letter of Certification’ to certify the specific model of inverter is compliant to the additional requirements of AS/NZS 5033.

Adjacent and physically separate d.c. isolator

When using an adjacent and physically separate d.c. isolator, due to the inverter not having an integrated isolator or the integrated isolator not meeting the requirements outlined above, ESV recommends the d.c. isolator is installed on a non-combustible surface (see appendix for details relating to non-combustible materials).

Where the surface is combustible ESV recommends installing a non-combustible barrier between the d.c. isolator and combustible surface. The non-combustible barrier should extend 200mm past the sides of the d.c. isolator. Any penetration of the barrier that has an internal free space greater than 5 mm diameter must be sealed with a fire retardant sealant.

Appendix

Guidance for non-combustible material

Non-combustible material has the same meaning in this document as is outlined in AS/NZS 5139 in cl. 4.2.4.2, 5.2.4.2, 6.2.4.2 (and DR AS/NZS 5033:2021).

The material is deemed to be not combustible when tested in accordance with AS 1530.1. Materials exempt from the need to be tested to AS 1530.1 and considered to be suitably non-combustible are:

  • Brick or masonry block
  • Concrete
  • Compressed cement sheeting
  • Ceramic or terracotta tiles