Check the wiring on a water heater by turning off the power and removing the water heater's cover plates to gain access to its internal wires. Use a voltage tester to determine whether the exposed wires are carrying an electric current or not.
Verify the voltage tester by connecting it with an outlet that is definitely working, making sure the voltage tester lights up or beeps in response to the voltage. Note that a metal conduit may cover the internal wires of the water heater, preventing the tester from reading the voltage. It may be necessary to remove the water heater's metal thermostat cover, pull out the insulation, and connect the tester where the wires reach into the top of the heater's high-temperature cutoff switch.
After testing these wires for voltage, use a continuity tester to determine if the water heater element is faulty or defective. Disconnect the element wires from the terminal screws, and connect the alligator clip to one terminal while touching the probe to the other terminal. The continuity tester lights up if the circuit completes successfully. If the continuity tester fails to light up, the water heater's element is burned out, and you must replace it.