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No, those flashes were not aliens landing on the North Shore

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Bright flashes during a storm surprised residents  

On the evening of November 17, three bright flashes occurred somewhere in North Vancouver. The blue-white light was intense enough to fully illuminate the North Shore mountains, and were captured by a handful of people in downtown Vancouver who were filming the storm activity on their mobile devices, including Sean Wilson, who tweeted his video (from which the image above was grabbed).

But aliens were not landing. Nor did the lights have anything to do with the production of new episodes of The X-Files currently filming in the area.

The three flares were caused by the discharge of electricity at BC Hydro's Capilano Substation when trees fell on wires during a typical winter storm. But while the cause of the lights was totally terrestrial, it was a spectacle.

"It was so neat," enthused Doug Trapp, who helps coordinate field operations for BC Hydro.

The power and potential of electricity on display

On the phone a few weeks after the storm, Trapp explained that, as a lineman by trade, he had lots of experience with B.C.'s electrical system during storms. "Nothing like it," he said.

What happened on the night of that storm, explained Trapp, is that high winds toppled a tree, which hit power lines near the Capilano Substation at the foot of Grouse Mountain in North Vancouver.

Because a live tree is a conductor – electricity can pass through it – the high voltage energy was suddenly grounded – instead of just flowing through the wires, the electricity also started flowing through the tree and into the ground. The sudden release of electricity at that moment created the two flashes of light.

It's not unlike the spark that occurs when you accidentally brush the positive end of your car battery against the engine block. But these sparks were big enough, because of the high voltage, to light up the entire North Shore.

Just like your home electrical panel, breakers keep things safe

Trapp said that even though the flashes of light seemed dramatic, the incidents didn't really cause any damage. Electrical systems are designed with safety in mind.

Power lines of all sizes are protected by breakers, which are rated for a certain amount of electricity to pass through them. If too much electricity starts flowing, or a short such as one caused by a tree falling on the line occurs, the breaker opens, breaking the circuit and stopping the flow of electricity.

When the tree hit the power line at Capilano Substation, and a greater amount of electricity started flowing through that line, a breaker in the system opened. That stopped the electricity from getting to the substation, which is why people living in the area experienced a power outage.

Your home is also protected with breakers. There's a main breaker at your electrical panel, which is rated for a particular amount of load, or amperes, to flow into and out of the breakers. When too much load is added to your home service (what you'll sometimes hear referred to as overloaded), or a fault occurs (such as an appliance malfunctioning or a nail going through an electrical line during a renovation), it automatically trips the breaker. Breakers can be reset, but if whatever caused the problem is still there, like a nail or a faulty stove, your breaker will continue to trip until it's fixed.

Sometimes breakers don't open, so keep yourself safe

Trapp was careful to stress that even though electrical discharges are spectacular, and electrical systems are mostly safe, it's important to realize that electricity can be dangerous.

"There is a chance that the breaker doesn't open," he said, recalling incidents when wires have come down and are still flowing electricity. "There's no way to tell," said Trapp, "if the conductor is energized or not."

If you ever see a fallen power line you should assume it is live with electricity. Call 911 and make sure to keep at least a bus-length away, about 10 metres (33 feet).

You might want to keep further away if aliens ever do land on the North Shore.