I opened another switch to check the wiring size. It is #14 so I suppose it is consistent with the rest of the normal outlets and switches (disregarding heavy duty appliances.) That having been said, I note that the heater has its own breaker. As I mentioned, I have been using it with a heavy-duty extension cord to an outlet where neither the panel breaker nor the appliance breaker is tripped. I presume that the only other demands on that outlet and other connections to the particular panel breaker are lamps. Notwithstanding its usability in those circumstances, is it unsafe? I suppose that the maximum wattage for a heater on 15 amp is 1440 less some allowance for other items on that breaker.