WA's electricity safety regulator has put Western Power on notice over the failure rate of wood power poles that carry electricity to thousands of homes, saying it is unacceptable.
The watchdog said the failure rate was above the accepted national industry standard and told Western Power to replace and reinforce suspect poles.
EnergySafety's warning, outlined in its 2014-15 business plan, came after Western Power's much-publicised problems with its wood small-pole network.
Known as distribution poles, they are typically found in suburban streets to take power to homes.
Transmission poles, on the other hand, transport energy between power plants and electricity substations.
They are usually much bigger than distribution poles and their failure affects more customers.
"Western Power has been requested to prepare and implement a more aggressive program of pole replacement and reinforcement for its transmission assets," EnergySafety reported.
Though it referred queries to Western Power, it is understood EnergySafety became aware of issues with the transmission poles only after several failed during winter storms in Perth last year.
It is also believed the assets that have been failing are transmission poles that are relatively small compared with some and so present less risk to public safety and electricity supplies.
Western Power acknowledged the failure rate was higher than acceptable and said that, like its distribution wood pole network, it stemmed from decades of government underinvestment.
Chief operating officer Andre Botha said that in the past three financial years the failure rate had more than doubled to about five per 10,000 poles.
He said Western Power was fixing "record" numbers of wood poles, having replaced 308 and reinforced 514 in the transmission network since July 1.
"The impact of decades of underinvestment in the network however is yet to be fully overcome despite the $650 million invested in replacing and reinforcing wood poles in the past two and a half years," Mr Botha said.
He said any pole failure was a safety risk but the transmission network had extra back-up to minimise the effects on supply.