Electric water heaters are one way of heating water in your home. They are quiet and pose none of the dangers that gas water heaters have with gas line connections and the danger of gas leaks. There are no vents required on electric water heaters, unlike the gas type water heaters. Electric water heaters require an electrical connection and a ground wire.
If you plan to replace a water heater, you'll likely need a permit do to plumbing, electrical, or venting specifications. The inspector will want to look over the connections and see that any piping is connected correctly. In fact, you may have to call licensed professionals in to make these connections. They'll be looking at the temperature and pressure relief valves (TPR) to see that they are functioning properly. If they don't the tanks can explode under extreme pressure.
There is an electrical connection plate atop the water heater that can be removed for installation. The connection should be made to a circuit breaker or fuse panel. Normally, the connection will be to a 2-pole breaker rated at 30 amps. The should be two hot wires and a ground wire.
Electric water heaters are connected to a 240-volt circuit, meaning two hot wires of two different phases. The ground wire is connected to the service ground and the other end is connected to the water heater ground connection. It is required and is there to protect you from electrical shock.
In the event that you are going to connect a #10 guage wire with a black, white, and bare ground wire, you'll need to wrap a piece of colored tape around the white wire on each end to signify that it is being used for a hot wire instead of a neutral wire. The water heater will come with a black and red wire. Simply connect the two black wires together with a wire nut, the red and marked white wire together with a wire nut, and connect the bare ground wire to the ground screw on the water heater.
As with any electrical repair project, turn off the power to the circuit that supplies the power to the device, in this case, the water heater. Always use an electrical tester to be sure that the circuit is off and that it is now safe to work on the electrical connections. Here are some common electric water heater problems. Follow this guide to troubleshoot electric water heaters. And if you need to, learn how to replace a water heater. I hope this helps you in replacing an electric water heater.