This is a general guide to identify the voltage of common aerial powerlines in South Australia. For exact voltage, contact:
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Knowing the different types of powerlines and their voltage means you can identify and maintain safe clearance distances
for:
- vegetation and trees on your property
- work or building near a powerline.
Types of powerlines
- Aerial – the height, design and construction will depend on their voltage
- Underground - common in new and high-density areas. First, visit Before You Dig to find out if there are any underground lines in the area. You might need to use a cable location service to locate them.
Transmission lines
Electricity (in kilovolts - kV) is carried from power stations to major substations on transmission lines. It’s carried at 132 kV,275 kV or 330kV.
Distribution lines
Distribution lines deliver electricity from substations to the community. The voltage will vary from 415V(low voltage) to 66kV (high voltage).
Stobie poles
Stobie poles are steel reinforced concrete poles that hold up the electrical wires. Their construction, and the type and
number of insulators can help you identify the voltage.
Transmission towers
Transmission towers carry high voltage powerlines. They are large steel structures, which 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. Higher voltages need larger insulators to separate them from the pole or tower.
Insulators can be:
- pin - small discs mounted on a rigid pin
- disc - larger discs attached to a wire.
The voltage of a powerline can usually be determined by the number of disc insulators. For example, a single disc usually insulates each 11 kV conductor.
Common 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 could be insulated and bundled together - an aerial bundled cable (ABC). The powerline could 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 could 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 have a sign that indicates 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 can be mounted on large single stobie poles.
275 kV powerlines are normally mounted on tall steel towers. Sometimes, they are mounted on double-poles, which are often shorter.
330 kV powerlines are mounted on tall steel towers.
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