Originally Posted by Jadavis

Why would you need to strip the insulation??? Resistance can be checked at the plug prongs. You need series to check current.

If you really care to find out if it is working buy a Kill-A-Watt. They are $30, but they have other uses. You plug it into the extension cord and then plug the heater into it. It will tell you how much power, current, etc you are using.

-Jim