Low and extra low voltage electrical installations

Electrical installations at low and extra low voltages need to be designed and installed in a way that ensures they will be safe to use. There are processes surrounding the choice of design, construction, certification, inspection, connection and periodic verification to make sure safety is maintained throughout the life of the installation.

Electrical installations at low and extra low voltage shall be installed in accordance with the requirements of the New Zealand Electrical Regulations.

During the construction of an installation, and at its completion, the installation work must be tested and certified. For those installations or parts of installations recognised as having higher risk of harm or damage to property by reason of their particular characteristics (hazardous areas, electrical medical installations, mains, etc) an independent inspection is required.

Finally, the installation work can be permanently connected to a supply after the certification, testing, and safety verifications have been completed and an ESC completed for the connection.

Unsafe works and installations

A person who does work on any works or installation must ensure that the resulting works or installation is electrically safe and the work has not adversely affected the electrical safety of the rest of the works or installation.

Regulation 20(external link) defines electrically unsafe works and installations.

Works and installations are unsafe if:

  • the characteristics of any fittings are impaired
  • the conductors are inadequately identified (eg the neutral conductor must be black and black must not be used for any other conductor)
  • the connections are not secure and reliable
  • cooling conditions are impaired
  • there is a risk of ignition (eg fittings subject to high temperature are unguarded)
  • cables are not protected against the risk of damage or are bent beyond their design criteria
  • there is insufficient space to work on the installations safely.

In addition, measures must be put in place to do at least one of the following:

  • prevent accidental contact with exposed parts
  • provide automatic disconnection of power if a fault arises that would cause injury
  • prevent or limit (International Electrotechnical Commission shock current Standards) electric current passing through the body of a person on contact of any part of the works or installations.

Design

Anybody who designs or supervises the design of, works, installations, fittings, or appliances must ensure that the finished design would be electrically safe.

Construction and certification

Information on the technical requirements for construction of low and extra low voltage installations.

Inspection and periodic verification

Electrical installations considered to be a high risk are subject to third party inspection. Particular electrical installations are required to be periodically assessed to determine whether they are electrically safe and otherwise comply with the regulations.

  • Warrant of electrical fitness
    Required for certain installations (Regulations 76(external link) to, 77(external link) and 78(external link))
  • Reconnection
    Certificate of Verification (CoV) required if the installation has been disconnected for more than six months 

Connection and metering

Certain checks must be undertaken before connection can occur.