Electrical Engineering - Voltage, Current and Resistance - Discussion

Insulator is a bad conductors of electricity. So it won't allows the electons in too it.

Electric charge carriers and ions are required to pass current from a substance. Insulators are non-conductor of electricity. Insulators cannot conduct electricity because they do not posses free electrons or charge carriers and ions. Ionic compounds in solid state are insulator. The forbidden energy gap is very large in insulators as compared to conduction band. Moreover, some insulators like ionic compounds can conduct electricity in molten or solution form due to the presence of free ions.