Roof heating cable is used in cold climates to prevent ice dams, melt snow, and prevent roof buildup. The reason for ice dum build-up is that the melted snow from the roof freezes on the edge due to temperature differences. The heating cable is usually installed in a zig-zag or V-pattern along the lower edge of your roof. The cables work by melting the ice along the edges of your roof, in the gutter system, and in the roof valleys.