Utility companies use a set of standards to determine the maximum tension in pounds that will occur on a wire due to wind, ice, temperature, wire size, wire type, span length, and support structure strength (poles).
The normal loading criteria is based on a 8 pounds per square foot wind loading, ?” of radial ice at 0 degrees F. The NESC limits the conductor tension to 60% of the maximum rated tension of the conductor used or 2000 pounds, whichever is lowest.
Hope this helps,
Newton1Law
Snowfall is nothing...even birds on a wire add more weight than that. And like BillRussel said, the core is a steel wire for tensile strength that will handle the biggest force which is wind. Since electricity flows around outside a conductor better than going thru the core, it makes sense for them to surround the steel core with a lightweight , cheap, conductor like aluminum which only has to worry about conducting current and not with strength issues.
The spec on the wires includes enough strength to handle reasonable loads, such as snow and wind and ice. Actually snow is a very light load, compared to ice and wind.
Usually they are a steel core with aluminum around it. The aluminum handles the current, the steel the mechanical loads.
There is usually a strength member wire that is incorporated into the cables that has no other purpose than support.
How do electric and other companies decide on strung wires in consideration of snowfall?
