Energy Safety is investigating a number of incidents in recent months in which machinery has come into contact with over head powerlines.
Earlier this week a crane operator at a White Gum Valley building site swung his jib into 132 kilovolt powerlines.
While the crane operator remained safe in his cab, a number of workers on the ground were at risk of electrocution from large metal objects becoming live.
Last month a similar incident occurred in Balcatta.
Energy Safety is investigating seven incidents where machinery has come into contact with powerlines since June.