Power will be switched on for the $275 million northern suburbs rapid transit system on Sunday, November 1.
Transport Minister Pam Beggs today said that on that date the overhead wires would be energised.
This meant the system would be live and there would be a period of testing to make sure everything was technically sound before the first electric trains ran on the 29.2 km line between Perth and Joondalup.
"It is important that all people working on the project and the public are aware well beforehand that the lines are live," Mrs Beggs said.
The overhead catenary system will carry 25,000 volts - 100 times the voltage connected to domestic residences.
The power is taken from SECWA's 132 kV system and transformed to 25 kV at Westrail substations.
It is fed via feeder stations to the overhead wires supported on 800 concrete masts along the line.
Mrs Beggs said the new power supply would allow the northern suburbs railway to operate independently in the unlikely event of a total power shut-down from the substation at Claisebrook. That substation was built to supply the Midland, Fremantle and Armadale lines.