What to do if your car hits power lines

Acting appropriately around fallen power lines could save your life, and others.

You should treat all downed power lines as being live wires. The coating is not insulation.

If a power line contacts the ground, a tree or vehicle, the ground becomes energized over a wide area. Electricity will spread out like ripples in water from the centre point of contact, though not necessarily in even rings. Each ring outward will have a decrease in voltage until it eventually drops to zero. If the ground is wet, voltages remain high over greater distances.

Anyone in the hot zone can get a fatal shock. This could happen, for example, by touching an energized source with your hand while your feet are on the ground, or simply walking on electrified ground. In either case, the difference in voltage from one extremity to the other causes electricity to flow through the body.

For safety, stay at least ten metres (one bus length) away from any fallen or low-hanging power lines, as well as vehicles or conductive objects (tree/fence/guardrail) in contact with it. Remember, electricity can arc through the air if you’re too close. Don’t stand underneath adjacent power lines, which may overheat and fall. Also, equipment on a utility pole may explode from the overload.

If a metal fence or guardrail is in the hot zone, voltages can remain high and deliver a fatal shock at great distances from the source, so keep clear over its entire length. Temporary lane striping, used in construction zones, also conducts electricity, so never assume you’re safe to stand on the road and gawk because you’re “far enough” away.

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Escape plan

If your vehicle contacts a power line, remain inside and call for help. Wait in the car until electrical workers arrive and give the all-clear. Warn onlookers to stay clear and tell them the ground could be electrified. If possible, drive away until you’re at least ten metres clear of the wire.

However, if your vehicle won’t move and there’s immediate danger from fire, fully open a door that’s away from fallen power line. Stand with both feet together on the door ledge, and then jump out and pull both arms in toward your chest. You must land with both feet together and not stumble. Never touch the vehicle and ground at the same time.

After landing, shuffle away keeping both feet close together, but not touching, and never let the heel of one foot move past the toe of the other. Alternatively, hop away by launching and landing with both feet close together. Short hops are safer to avoid stumbling or falling. Keep going until outside the ten metre danger zone.

These are last-resort escape recommendations from electrical utilities for dire emergencies only. Use it at your own risk and always stay in the car wherever possible.



The science behind the escape

The reason a person standing on electrified ground can’t walk away normally is because each foot would land in a power ripple with a different voltage. The resulting voltage difference will cause electricity to flow through your body, up one leg and down the other. Shuffling or hopping aims to avoid this.

While tires may smoke or explode, don’t exit the vehicle unless there’s actually a fire. After high voltage exposure, tires may suffer internal damage resulting in explosive failure within 24 hours — even if deflated. Other motorists who foolishly drive into the hot zone or over fallen wires likewise risk an explosive blowout of all tires up to a day later.

Never spray an electrical fire with a garden hose, you could die. Even firefighters must stay back and use high-pressure water in a fog pattern to avoid being shocked.

If a main transmission tower line has fallen, rather than a roadside utility pole wire, the minimum safe distance is 32 metres.

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