Powerline safety

Identifying powerlines

There are a number of types of powerlines in South Australia. To maintain safe clearance distances between the powerlines and vegetation on your property, or if you are working or building near powerlines, it is important to know the correct voltage.

This page provides a general guide to voltage identification of common aerial powerlines in South Australia only.

To find out the exact voltage contact SA Power Networks or the Office of the Technical Regulator.

Aerial and underground powerlines

Powerlines in South Australia can be aboveground (aerial) or underground.

Aerial powerlines

Aerial are the most common type of powerlines. The construction, size, height and design of these lines vary depending on their voltage. You can find a general guide to identifying these lines on this page.

Underground powerlines

Underground powerlines have been used since the mid 1970s and are common in new developments and high-density areas. Underground powerlines reduce the risk of accidental contact but can be hazardous if you are digging near them.

Before you start digging, find out the exact location of any underground lines by calling 1100 or visiting the Dial before you dig website.

Transmission and distribution lines

Transmission lines

Transmission lines are used to carry electricity (in kilovolts, or kV) from power stations to major substations. In South Australia, transmission lines carry electricity at either 132 kV (132,000 volts) or 275 kV (275,000 volts).

Distribution lines

Distribution lines are used to deliver electricity from substations to homes and businesses. The voltage of electricity conducted by distribution powerlines may vary from 415 volts (V), which are low voltage, to 66 kV (66,000 volts), which are high voltage.

Typical powerlines in built-up areas, including  11kV high voltage lines, low voltage lines and supply lines.

Stobie poles and transmission towers

Stobie poles

Stobie poles are single steel-reinforced concrete pole structures on which powerline conductors (wires) are mounted or strung. Pole construction and type and number of insulators normally indicate the voltage of the powerline.

Common stobie poles in South Australia are 66,000 volts, 33,000 volts, 19,000 volts, 11,000 volts and 415 volts.

Transmission towers

Transmission towers are large steel structures that are used to carry high voltage powerlines. Transmission towers are usually found on the edge of or outside metropolitan areas.

Common transmission towers in SA are 275,000 volts and 132,000 volts.

Powerline insulators

Insulators are used to separate bare conductors (wires and cables) from the stobie pole or tower structure. The higher the voltage carried by the conductor, the larger the insulators that are used to separate them from the pole or tower.

Insulators may be of a pin type (one or a number of small discs mounted on a rigid pin) or disc type (larger discs that are attached to a wire). The number of disc insulators is usually indicative of the voltage of the powerline, eg 11 kV conductors are generally insulated by a single disc (one disc for each wire).

Common types of powerlines in South Australia

415 V distribution lines

Voltage415 V
Number of conductors4
Type and number of insulatorsSmall pin insulators
Height of powerlineCommonly 6 to 7 metres (can be as low as 4.5 metres)

Wire conductors may be insulated and bundled together, which is called an aerial bundled cable. The powerline may have between two and five conductors.

415 V powerline with four conductors and two insulated service lines

A pin insulator used on 415 V powerlines

415 volt insulated aerial bundled cables (ABC)

11 kV lines

Voltage11,000 V (11 kV)
Number of conductors3 bare conductors
Type and number of insulatorsSingle disc insulator or a pin insulator made of 3 smaller discs
Height of powerline8 to 9 metres above ground (11 kV lines are usually mounted 2 metres above 415 V lines)

Wire conductors may be insulated and bundled together (aerial bundled cables).

11 kV single disc insulator

11 kV powerline (upper three conductors) with 415 V powerline (lower four conductors)

11 kilo volt pin insulator

11 kV pin insulator

19 kV SWER (single wire earth return) lines

Voltage19,000 V (19kV)
Number of conductorsSingle bare wire conductor

This type of powerline is commonly found in rural areas.

SWER line poles with transformers are normally affixed with a sign indicating a no dig zone.

19 kV SWER powerline

33 kV lines

Voltage33,000 V (33kV)
Number of conductors3 bare wires
Type and number of insulators3 disc insulators or pin insulators made of 3 smaller discs
Height of powerline10 to 20 metres

33 kV powerline with two sets of conductors

Glass disc insulator used on 33 kV powerlines

66 kV lines

Voltage66,000 V (66 kV)
Number of conductors3 bare active wires
Type and number of insulators5 or 6 disc insulators or a post insulator made of a stack of 12 smaller discs
Height of powerline10 to 20 metres

66 kV wishbone powerline

66 kV triangular powerline

66 kV vertical powerline

Disc insulators used on 66 kV powerlines

Stack of disc insulators used on 66 kV powerlines

132 kV and 275 kV lines

Voltage132,000 V (132 kV) and 275,000 V (275 kV)

Transmission lines are usually mounted on steel towers.

132kV powerlines may be mounted on large single stobie poles.

275kV powerlines are normally mounted on tall steel towers, however, they are sometimes mounted on double-pole structures that are usually shorter than steel towers.


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Page last updated 13 April 2017

Provided by:
Department of the Premier and Cabinet
URL:
https://www.sa.gov.au/topics/energy-and-environment/using-electricity-and-gas-safely/powerline-safety/identifying-powerlines
Last Updated:
13/04/17
Printed on:
23/08/17
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