I have never used Zoo Med heat cable but i have seen the stuff in several pet stores. The way this heat cable looks, it is designed with a resistor at the end of the cable (enlarged capped end) and a cold section probably within a foot or two of the plugin. I'm willing to bet the instructions that came with this cable states the standard "do not overlap or kink this cable". This is for overheating/failure precautions. I would say with certainty the instructions say "do not cut this cable". By cutting this style of cable you would have an open circuit thus failed cable. The section of cable that you cut that contained the end piece would work if wired up in a way that would get extremely (fire hazard level) hot. This would be due to the cable being shortened and thus changing the resistance.
Please do not cut this style of cable. I have worked with heat cable for many many (38) years in the electric utility business keeping pipes from freezing in our power plants. We use lots of heat cable in our plants that can be cut to any length and doesn't use a resistor. It's power is calculated at "X" watts per foot. Pre-fab heat cable of Zoo Med design is calculated at total watts for the entire length of cable.
Please use this cable in it's unaltered state with a thermostat or find a different option that better suits your needs.
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