Thousands of wooden power poles similar to the one that sparked a fire in Chidlow last week could be 50 years old and liable to fall over, WA's energy safety watchdog has warned.
Barely a year after it emerged a quarter of Western Power's 630,000 wooden poles were unsafe, EnergySafety said the problem was rife among thousands of poles on private land.
EnergySafety acting director Don Saunders said the owners of about 7000 properties in the south-west grid between Geraldton and Albany were responsible for electricity infrastructure such as poles and wires.
This number could be higher when remote areas were included.
Mr Saunders said much of the infrastructure was installed as far back as the 1950s when costs were kept to a "bare minimum" to ensure as many areas received network power as possible.
It was likely many of the poles had not been replaced or reinforced since then, raising the spectre of a repeat of the Chidlow fire.
The fire, which burnt down sheds and 15ha of farmland, was caused when ageing wooden power poles toppled in strong winds and brought live powerlines down into dry grass.
It emerged the poles, which were installed in 1969, were the responsibility of the property's 79-year-old owner Pat West, because they connected her house to the grid.
Mr Saunders said the case highlighted the risks associated with old power infrastructure.
He said the problems were exacerbated by confusion over who was responsible for wooden poles and rules that invariably meant only licensed electrical contractors could do the work. Former Nationals MP now independent Max Trenorden, who headed a parliamentary committee critical of Western Power's handling of its pole network, said the issue was poorly understood.
He said many landholders were unaware of their responsibilities and Western Power had a moral obligation to help them. "A 79-year-old woman hasn't got the capacity to test poles like a line crew," Mr Trenorden said.
A spokeswoman said Western Power always helped people understand their obligations but it was not the utility's responsibility for maintaining or assessing privately owned infrastructure.
She likened poles that connected properties to the network to the wiring inside a house.