Temperature Ratings | Anixter The temperature ratings of wire and cable products are key operating parameters. The use of wire and cable products outside their design temperature range can result in premature and often expensive failures in service. Some of the most common temperature ratings used in the wire and cable industry are discussed below. Is Your Electrical Wiring Too Hot? - Copper Is Your Electrical Wiring Too Hot? October 2004. New Study Finds Attic Temperatures Can Pose Serious Risk. If you've ever been up in your attic on a sunny summer day, you know the meaning of hot. If you have a dark color roof on your house, the heat buildup in the attic can be unbearable.