Turn off the electric water heater breaker inside your breaker panel.Remove the electrical junction box cover from the top of the water heater to expose the electrical wiring.Turn the dial on a multimeter to 250 AC (alternating current) and insert a probe from the multimeter into the wire connector joining the two black wires while touching the other probe to the metal on the water heater tank. The needle remains at zero on the multimeter when no electrical current is detected. Insert the probe into the connector joining the red wire from the water heater to the white wire wrapped in black electrical tape to repeat the test. The white wire is designated as a hot wire in this wiring application.Untwist the wire connectors holding the red and black wires from the water heater to the electrical supply cable. Depending on your water heater, a connector joins a green wire from the water heater to the bare copper wire from the electrical cable or the copper wire connects to a green ground screw on the body of the water heater. Disconnect the grounding wires by either untwisting the wire connector or loosening the green ground screw.Untwist the locknut holding the electrical supply cable to the water heater. Reach inside the water heater junction box to loosen the locknut. Pull the cable from the water heater.Remove the mechanical timer from the timer housing and remove the 1/2-inch knockouts on each side of the housing. Position a screwdriver on the knockout and strike the screwdriver with a hammer. Grab the knockout with pliers and twist until it disconnects from the housing.Drill wood screws through openings on the mechanical timer housing to mount the empty housing on a wall stud. Thread the electrical supply cable through the knockout on the left of the timer housing and secure it with the locknut you removed in Step 5.Thread a 10-2, pre-assembled 1/2-inch electrical whip to the knockout on the right of the housing. The whip is assembled with the wires pre-stripped and the connectors attached. Secure the whip to the housing with the locknut provided with the whip.Insert the opposite end of the whip through the opening in the top of the water heater where you removed the electrical supply cable in Step 5 and secure it with a lock n u Twist a red wire connector onto the black wire from the whip and the black wire from the water heater to join them together. Repeat the connection for the red wire from the whip and the red wire from the water heater. If your water heater has a green wire, connect the green wire from the whip to the green wire from the water heater with another wire connector. If your water heater ground connection is a green ground screw, wrap the green wire from the whip around the ground screw and tighten it. Replace the junction box cover onto the top of the water heater.Reinstall the mechanical timer into the housing.Wrap the black wire from the electrical supply cord around the far left screw on the timer and tighten it. Wrap the green or bare copper ground wire from the supply cord and green wire from the whip around the green ground screw on the far right of the timer and tighten it.Wrap the black wire from the whip around the screw directly to the left of the green ground screw and tighten it. Wrap the red wire from the whip and the white wire wrapped in black electrical tape from the electrical supply cord around the remaining screw on the timer and tighten it.Turn the breaker on for the water heater and supply electricity through the Intermatic WH21 timer.
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