Can I use a regular extension cord or adapter plug with the GSC470 dishwasher?

No, you must not use an extension cord or adapter plug with this appliance. The dishwasher must be supplied with 120V, 60Hz power and connected to an individual, properly grounded branch circuit protected by a 15 or 20 amp circuit breaker or time-delay fuse. Do not, under any circumstances, cut or remove the third grounding prong from the power cord. (Page 11)