Motorists heading north on the M1 Princes Motorway on Mount Ousley, north of Wollongong are urged to take care.
Shortly after 11.30am a loaded petrol tanker travelling north up the mountain was involved in an accident and brought down live power lines.
It was reported the lines are lodged in the bonnet of the truck, which is carrying 35,000 litres of fuel.
Emergency services and Roads and Maritime Service crews are on the scene.
North bound traffic is stopped, with police taking the decision to close the south bound lane past the accident, where cars come within 25 metres of the truck.
North bound traffic is being diverted on the Northern Distributor, while south bound traffic is being diverted down Bulli Pass.