Accumulations of windblown road salt on insulators caused shorting that set power poles on fire and produced traffic chaos in Calgary Wednesday morning.

ENMAX spokesman Peter Hunt said crews put out about a dozen burning power poles in the southeast. The fires started when milder weather added to the melting of snow and ice on roads sprayed by salt.

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Crews work on a Calgary power pole after a buildup of windblown road salt on insulators caused shorting that set it on fire. ((CBC))

"And if there's also windy conditions, then that turns into a salt spray that can coat the insulators that sit at the top of power poles. If enough of that builds up, then it can conduct electricity across the insulating gap," he told CBC News.

"The current jumps the gap, it shorts out the system, and then because of the creosote in the wood on the pole, it also sets the pole on fire."

Blackfoot Trail was closed between Ogden Road and 34th Avenue S.E. as crews replaced burned power poles.

At least 7,000 people in the southwest found themselves with no electricity Wednesday morning. By 11 a.m. local time, fewer than 1,000 ENMAX customers were waiting for power.

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Crews replace a power pole, one of about a dozen that caught on fire after a short-circuit, in southeast Calgary. ((CBC))

Power outages were also reported in the northwest and northeast near downtown, as well as sporadic blackouts in the southeast, Lake Bonavista, Willow Park and parts of the Foothills Industrial Park.

Calgary police urged motorists to slow down and use caution, as the overnight snowfall of about five centimetres made roads extremely slick.

"Lanes are obscured. Lane markings are obscured. You're just going to have to really decide to slow down a bit, drive safely and expect long delays," said duty Insp. Luch Berti.

6 taken to hospital after crash

Several problems hit 16th Avenue N.W. throughout the day. Traffic was rerouted on the Shouldice Bridge near 16th Avenue and Home Road after a three-vehicle collision just before noon.

Six people have been sent to hospital, including a 32-year-old woman in critical condition and two children, ages 2 and 7, in stable condition.

During the morning commute, several cars were pulled over with flat tires near the 16th Avenue N.W. off-ramp to Sarcee Trail. There were reports a sheared section of a metal sign lying on the road caused the flat-tire headaches.