The Icing Event Guide for Utility Operators

Connecting disparate energy centers and traveling through some of the most remote areas, our transmission lines are constantly exposed to different atmospheric conditions. Local weather can have huge impacts on transmission lines’ physical states and operations. While hotter temperatures generally mean more significant transmission line sag and stress on the transmission system than cooler days—cold weather presents its own set of challenges to system management due to threats from icing events. As climate crisis impacts bring more low-probability and high-impact weather events, including more cold snaps and polar vortexes, one task that utilities are eager to address is improving grid resiliency by best managing icing events.

Ice buildup on power lines, or icing, can be a common issue for utilities in cold or temperate regions, where storms can deposit thick layers of ice on power assets, including transmission lines, towers and shield wires. Icing typically builds up in temperatures ranging from -15°C to 2°C and can be unpredictable, taking anywhere from several days to less than an hour to build to a critical weight load. Adjacent spans and lines can experience icing differently so that ice can fall from one line while remaining built up on another.