There are a few steps you want to follow for an electric hot water heater startup. Turning the breaker or water on prematurely can cause problems and may ruin the heating elements.
There are several repairs that on an electric water heater that require you to partially or completely drain the water out of the tank. The procedure below assumes that the tank has been drained.
If you did not drain the tank, but shut the water off, you still want to follow the procedure for turning on the water, to make sure the tank is full before the power is turned on. If only the power was turned off, follow the electrical segmetn below.
Close the Drain Valve
Close the drain valve at the bottom of the tank. Remove the hose that you used to drain the tank and clean up any excess water. Make sure the drain valve is tight.
Dry off the area around the valve and the valve itself. You are going to want to watch when the water is turned on, to make sure it is not leaking.
Turn On the Cold Water Supply
Shut off any of the valves or faucets in the house that you may have opened when you drained the tank.
Turn the cold water supply line at the top of the tank. You should be able to hear the tank filling at this point.
There should not be a valve on the hot water side of the tank. If there is, make sure that it is open.
Wait for the water heater to completely fill with water. Try a couple of the faucets and bleed out the air to make sure the tank is full.
Turn On the Power
Hopefully, you followed a safe procedure for shutting off the power and 'tagged' or 'locked out' the breaker for the water heater. This is a good practice whenever you work on anything with electricity in your home. See the article 'Shutting Down an Electric Water Heater' and 'Electrical Safety at Home' for more information.
Turn the breaker on for the hot water tank after the tank is filled with water. It will take a while for the water to warm up after it has been completely drained down. Only one element heats at a time and it may take a while for the water to heat back up completely.
You should be able to hear a humming noise when the elements are heating. This will let you know that the water heater is working. After an hour, you should have warm if not hot water.
This article has given you the steps that should be followed when you restart an electric water heate after it has been shut down. Turning the power back on too soon can damage the elements, avoid problems and follow the steps.