This page explains why Warmup does not recommend you cut the wire for any reason and provides solutions to having too much cable.
Warmup’s loose cable is best suited for small, irregularly shaped spaces. It features a double-insulated wire with advanced fluoropolymers. The loose wire carries a high ohms resistance allowing it to provide heat outputs 25%-40% than any other cable on the market. Additionally, Warmup loose wire is backed by a lifetime warranty.
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