Around 25,000 homes are without power in Perth and parts of the South West after light rain and dust on the insulators caused a massive power outage.
Western Power said in a statement on Thursday morning the rain combined with dust on insulators after the state's recent hot spell together with strong easterly winds over the last week caused the power failures in the metropolitan area, reaching as far south as Bunbury.
"This combination is causing safety mechanisms in the system to act as they are designed to and trigger a safety response to protect the network from damage," the statement said.
"The most affected suburbs are located along coastal areas across the network but includes some areas to the east.
"Western Power crews are currently assessing the damage to the network and prioritising any hazards that are identified before restoration will commence."
A spokesman for Western Power said crews were working to restore electricity.
He said traffic lights may also be out so motorists needed to take care.
"Extra crews have been mobilised from other duties to assist emergency response teams to help speed up the restoration efforts," he said.
If you see a fallen powerline please make the safe call to Western Power and report the hazard on 13 13 51.