How much ice causes power outages?

Any ice that sticks to the ground is a hazard. But the more that adds up, the less anyone should be traveling. Here are different impacts and amounts.

BLOWING ROCK, N.C. — Freezing rain can be treacherous. Where even small amounts can lead to big issues. Here are the impacts of different amounts of freezing rain.

Less than a 0.10″ of freezing rain

When freezing rain first starts, roads and sidewalks develop a thin, nearly invisible layer of ice. Around 0.01 and 0.1 inch of ice creates insidious conditions since drivers and pedestrians often can’t see the hazard. Even these small amounts make bridges and overpasses especially dangerous since those surfaces freeze first.

0.10″ to a 0.25″ of freezing rain

Between a tenth-and-a-quarter inch, ice begins coating tree branches and power lines. Road conditions worsen significantly with very slick surfaces making steering and braking difficult. Most agencies advise against any non-essential travel at this point.

0.25″ to 0.5″ of freezing rain

Once accumulation reaches a quarter-and-a-half inch, widespread power outages become likely. A quarter-inch of ice coats the lines and significantly increases the weight of power lines. This added weight can cause lines to sag, break, or even snap.

When roads become extremely hazardous snow plows and salt trucks struggle to operate safely. Emergency vehicles may have difficulty responding to calls for asssitance.

Over a half inch of freezing rain

Above half an inch, travel becomes nearly impossible for almost all vehicles. Half an inch of ice can add as much as 500 pounds to power lines.

After a half an inch of ice, tree damage is severe, roads may be blocked by large fallen limbs and power outages can last for days. At this level, entire geographic regions may effectively shut down until temperatures rise above freezing and the ice melts. Then there is often a chance for a re-freeze.

Contact Chris Mulcahy at cmulcahy@wcnc.com and follow him on Facebook, X, Instagram and TikTok.