Which electronics are you using? I guess Gen6 from Mendel-parts seeing as you have their hot end.
See here: [
reprap.org]
The wires from the resistor and thermistor are NOT insulated, and you need to be careful that they don't earth out on the hot end. Easiest thing to do is put a wrapping of kapton tape on the them, or get high temperature ptfe shrink tubing. See here for general advice about the installing thermistor/resistor [
reprap.org]. High temperature epoxy/sealant is easier to use than fire cement, but make sure it can withstand temperatures of 250ºC.
