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Lightning strikes!

It’s that time of year; the time when Mother Nature puts on her annual light shows.  In recent years, those shows have become increasingly spectacular. 

In 2008 data collected by Environment and Natural Resources recorded 78,315 strikes over a 24-hour period, a new record.  It was a summer of discontent as dramatic lightning storms rolled down the Mackenzie Valley from the Arctic Ocean almost weekly.

While the frequency of lightning storms is increasing, so too is the intensity as “positive” strikes continue to rise.  Positive lightning strikes were only confirmed by science in 1973.  Prior to that all lightning was thought to be a negative electrical discharge.  An average bolt of positive lightning is about 10 times more powerful than a negative strike and they’ve been known to knock major aircraft out of the sky.  Today, positive lightning accounts for 5-6% of all strikes in any electrical storm. After the storms of the past few years, NTPC recently replaced 18 lightning arrestors on the Snare Transmission Line to protect the system serving Yellowknife.

Line crews take to new heights to replace lightning arrestors on the Snare Transmission Line.

Lightning strikes on a transmission line can cause electrical surges. These surges travel down the electrical system damaging power infrastructure, causing outages, or destroying home electronics.  Lightning arrestors protect the system by diverting the lightning surge to the earth by way of a ground wire.

“During the summer months, it’s not uncommon to have thousands of lightning strikes in a single day around the Snare line,” says Brian Willows, NTPC’s Chief Operating Officer, “Ensuring that our arrestors are in proper working order is a necessary precaution that greatly reduces the chance of system outages and damage to our infrastructure.”

Later this summer the Corporation plans to install six more lightning arrestors at substations on the Snare hydro system.

NTPC monitors all lightning strikes in and around the Snare system from its control centre in Yellowknife. 

Lightning arrestors mitigate system outages and high voltage system surges.  But nothing is failsafe against a bolt of lightning.  The Power Corporation encourages all customers to purchase suitable surge protection, such as an Uninterruptable Power Supply (UPS), for sensitive home electronics.