[ctt956]

I think safety is the biggest issue with suicide cables. As others have said, a stalled motor could draw dangerously high current. Depending on how to cables are connected, a wire short hazard may also exist due to how easily the exposed wires could contact each other. Having a breaker would not only protect the circuit, but also allow you to turn it off quickly and easily should you need to do so. As for the potentiometer, definitely make sure it can handle the current you intend to run through it. I once put a small potentiometer in a circuit with a smallish 12V fan as an attempt at speed control. The device that originally had this pot ran on 12 volts DC, so it seemed like it could work. There was nothing else on the circuit. I might have connected something incorrectly, because I don't think the fan worked, but there was some magic smoke from the potentiometer.