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High voltage electrical installations

Unlike a low voltage installation which is generally designed and constructed in accordance with technically prescriptive requirements, most high voltage installations are unique to their application and are designed according to electrical engineering safety principles. As a result, the Regulations that apply set fundamental safety requirements only.

In addition, high voltage installations require planned ongoing maintenance and are often designed as a part of or closely interact with the electricity distribution supplying theme. As a result, the Regulations implement explicitly a number of measures that apply the same principles and practices across the supply systems/installations interface.

Reflecting the engineered installation philosophy, the Regulations achieve control through identifying the factors that need to be addressed during design and construction and by defining characteristics that are considered to be unsafe.


The requirements relating to high voltage installations around safety obligations

High voltage installations require a certified design.


High voltage installations

Design General safety requirements
Reg 14

Technical rules
Safety requirements relating to overhead lines, earthing systems, isolation from supply of electricity, conductors and notices (Reg 41 to 46).

Certification is required


All high voltage installations are subject to testing (Reg 38) and third party inspection (Reg 70 to 72)

Safety check
Reg 73 (4)

Periodic verification In service safety verification
Reg 41 (1)(2)


Defining unsafe works and installations

Regulation 20 defines electrically unsafe works and installations. Works and installations are unsafe if:

  • the characteristics of any fittings are impaired
  • the connections are not secure and reliable
  • cooling conditions are impaired
  • there is a risk of ignition (e.g. fittings subject to high temperature 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 arise 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.


Periodic verification

There is a requirement to implement a safety checking system (Regulation 40) that must:

  • verify compliance with all the requirements
  • occur periodically at reasonable intervals
  • ensure records of results are being kept.



Anybody who designs or supervises the design of, high voltage installations must ensure that the finished design would be electrically safe.

Read more about Design


Engineering safety principles through the Regulations achieve control through identifying the factors that need to be addressed through construction.

Read more about Construction

Inspection and connection

Electrical work on installations that operate at high voltages must be inspected.

Read more about Inspection and connection

Last updated 25 September 2015
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