Hello buddy and thank you for this question.
Only the 2-1/2 gallon model is supplied with a plug connected power supply cord for use only in 120 VAC applications. The 10 gallon model is completely wired to the junction bracket inside the jacket at the front of the water heater. You may need to contact a licensed electrician to properly install the unit for you.
See page 17 of the Electric Point of Use Water Heaters Use & Care Manual for wiring instructions: http://www.homedepot.com/catalog/pd...
Best wishes on your project.