Melted Electrical Tape Toxic?
Well the (PVC) tape by itself isn't according to its material safety data sheet, (see http://www.lhdottie.com/pdf/msds/360_%28PVCTape%29.pdf) but because of the high chlorine content it does tend to give off pretty nasty smelling vapours (HCl) which can be irritating. 

In large amounts burning PVC could produce dioxins but for a small piece of tape I wouldn't consider that a real problem.