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.
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.
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.
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
| Voltage | 415 V |
|---|---|
| Number of conductors | 4 |
| Type and number of insulators | Small pin insulators |
| Height of powerline | Commonly 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
| Voltage | 11,000 V (11 kV) |
|---|---|
| Number of conductors | 3 bare conductors |
| Type and number of insulators | Single disc insulator or a pin insulator made of 3 smaller discs |
| Height of powerline | 8 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 kV pin insulator
19 kV SWER (single wire earth return) lines
| Voltage | 19,000 V (19kV) |
|---|---|
| Number of conductors | Single 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
| Voltage | 33,000 V (33kV) |
|---|---|
| Number of conductors | 3 bare wires |
| Type and number of insulators | 3 disc insulators or pin insulators made of 3 smaller discs |
| Height of powerline | 10 to 20 metres |
33 kV powerline with two sets of conductors
Glass disc insulator used on 33 kV powerlines
66 kV lines
| Voltage | 66,000 V (66 kV) |
|---|---|
| Number of conductors | 3 bare active wires |
| Type and number of insulators | 5 or 6 disc insulators or a post insulator made of a stack of 12 smaller discs |
| Height of powerline | 10 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
| Voltage | 132,000 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.
