They will melt snow ice in direct proximity but if you have 3 feet of snow most of it will likely stay there.
Roof coils to melt the snow.
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Clip in the cable along the same zigzag pattern as the shingle clips.
To be fair heat cables are pretty inexpensive so it s worth a try especially if you can go up on the roof yourself and attach them.
In this video master electrician for ask this old house scott caron helps a homeowner install heat cables on his roof to stop ice dams.
Most coils operate by just plugging them in but some will be connected to a switch or thermostat.
As for when to use them they are intended to prevent ice build up when temperatures are causing.
Snow is porous and allows water to flow.
Install heat cables to melt the snow at the edge of the roof.
Secure shingle clips to roof shingles using a flathead screwdriver making sure to align them in a zigzag pattern.
These are also called deicing cables and they can be found at your local hardware store or online.
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