Damaging winds saw thousands of Sydneysiders lose power last week, but “reckless vandals” who took a chainsaw to power poles contributed to outages for more than 700 customers.

Ausgrid crews found the damaged poles near Bloodwood Road at Fiddletown on Friday night and had to cut away high voltage wires to make the site safe.

Police are investigating "reckless vandals" who took a chainsaw to power poles in Sydney's north. Credit:Ausgrid

Ausgrid Chief Operating Officer Trevor Armstrong condemned the behaviour of the “reckless vandals”.

“I can’t state enough just how dangerous and irresponsible this behaviour is,” he said. “It is the height of stupidity to cut down a power pole carrying live powerlines, we are incredibly lucky nobody was killed or seriously injured.”