Electrical hazards are one of the leading causes of serious EWP incidents in Australia. The risk is not always from direct contact — the electric arc from a conductor can travel through air, especially in high humidity or when voltage levels are high. Understanding exclusion zones, approach distances and the distinction between insulated and non-insulated EWPs is essential for any operator or site supervisor working around live electrical infrastructure.
Exclusion zones around live conductors
An exclusion zone is the defined space around a live electrical conductor into which no part of a person, machine, tool or load may enter without specific authorisation and control measures. The boundary of the exclusion zone is set at a distance that accounts for the voltage level of the line and the potential for arc flash.
Exclusion zones apply to the entire machine — not just the basket. The boom, the truck body, and any material being carried must all remain outside the exclusion zone boundary. When the boom is moving, the swept path of the machine must also remain clear.
Insulated vs non-insulated EWPs near live lines
A non-insulated EWP provides no electrical protection between the basket and the truck chassis or the ground. If the basket contacts a live conductor, current will travel through the machine structure, potentially reaching the outrigger pads and anyone in contact with the truck on the ground. Non-insulated machines must not work within the exclusion zone of live conductors.
An insulated EWP has a rated dielectric break in the boom structure — typically a fibreglass section — that provides a barrier between the upper and lower machine. The insulation is rated in kilovolts (kV) and indicates the maximum line voltage the machine can work near with the basket in the exclusion zone. The insulation protects the operator but does not make the machine immune to electrical risk — it provides a defined level of protection under controlled conditions.
kV ratings and what they mean
An insulated EWP's kV rating (for example, 33kV dry, 15kV wet) specifies the maximum system voltage the boom insulation is rated to withstand in the stated conditions. Dry ratings apply in normal weather; wet ratings — which are lower — apply when the insulation surface is wet from rain, condensation or humidity.
The kV rating must be matched to the voltage of the conductors being worked near. Working a machine rated for distribution voltage near high-voltage transmission lines is a serious and potentially fatal mismatch.
Maintaining boom insulation
Insulation that is cracked, contaminated with conductive fluids, or degraded by UV does not perform to its rated kV. The insulating section of the boom must be inspected and tested as part of the machine's regular maintenance and at each major inspection. Live line testing — applying a test voltage to the insulated section — is the only way to confirm the insulation is performing to its rating.
Carrying conductive materials (metal conduit, steel cable, long metal tools) through the insulated section of the boom can create a current path that bypasses the insulation entirely.
This guide is general information prepared by EWP Australia and is grounded in publicly available Australian Standards and Safe Work Australia material. It is not a substitute for the current published edition of the relevant standard or for site-specific engineering advice. Always work from the current standard and consult a competent person for your specific equipment and application.