I live in South Florida. Hurricanes happen, and knock the power out for weeks at a time when they do.
I don't need water that's steaming hot, but I really want to be able to take showers that are at LEAST "tolerably tepid" when running from generator power for days or weeks at a time (when connected, the water heater could be the generator's ONLY load if necessary).
The devil, of course, is in the details... specifically, I'm strugging to figure out how many amperes my water heater will draw when powered by 120 volts instead of 240 volts, so I can size the wire and plug appropriately.
Based on my understanding of Ohm's Law, when fed 120v (pin mapping below), the water heater will draw 9.375 amperes, and its heating coils will output 1,125 watts of heat. As far as I know, it's a straightforward pure resistive load, and only one heating element at a time is ever in use (top heats until water reaches set point, then bottom heats until either bottom reaches set point or top falls below set point). This seems to imply that when running, the water heater would draw slightly more power than a toaster (9A), but slightly less power than my laser printer (11A when preheating the fuser or actively printing).
Is this correct? Would it REALLY draw only 1,125 watts (9.375 amperes) from the generator? Do I have the connections right, or are there additional things to consider with regard to neutral and ground?
Details:
I live alone, so I don't have to supply hot (or at least tepid) water to anyone besides myself.
My hot water heater (unlikely to be replaced anytime soon) is a standard 40-gallon electric water heater (US/Craftmaster Water Heater Company, model E1F40RD045V). It's 10+ years old, and has no "smart" features or electronics whatsoever.
The sticker on the side lists the following specs:
Phase 1 1
Volts AC 208 240
Upper Element 3380 4500
Lower Element 3380 4500
Total
Connected
Watts 3380 4500
The water heater has a standard NEMA 10-30 plug. The two hot leads from its power cord are connected to something inside the water heater, and the middle (neutral) lead from the power cord is connected to a screw on the water heater's chassis.
Wiring Plan:
Build a custom extension cord with receptacle suitable for the water heater at one end, and plug suitable for the generator at the other. When connected to the generator, the water heater would be its ONLY load.
- 120v generator hot to water heater's "240v" hot #1
- 120v generator neutral to water heater's "240v" hot #2
- 120v generator ground to water heater's "240v" neutral (which is actually bolted to the water heater's chassis).