Electric water heater wiring can be a very dangerous job.  However, if you pay attention to what you are doing, it can be a fairly simple job.  Electric water heater wiring carries a 240 volt circuit.  This voltage is dangerous and has been known to cause severe injury or even death.  Hot water heater problems are not common but could be very expesive if you don't fix it yourself.

Materials and Tools:

• Two-pole, 30-amp breaker (for conversion)
• 10-2 NM cable (for conversion)
• Voltage tester
• Needle nose pliers
• Wire strippers
• Clamp
• Clamp screws
• Lock nut (included with water heater)
• Electrical tape
• Electrical wire connectors

Steps for hot water heater wiring:

If you are replacing an existing hot water heater, the circuit will be on site.  However, if you are converting to electric from a gas-heated unit, you will need to run the circuit.  For this job, you will need a two-pole, 30-amp breaker and 10-2 NM cable to run for your circuit.  

Note:  Do not fill up tank with water until tank is wired up, and do not turn on circuit power until tank is filled with water.

1. The top or side of the hot water heater will have a junction box cover.  This is where the connections will be made.  Take the screw and the cover off.  Inside the box will be two lead wires and a ground screw.  
2. Use a voltage tester to ensure that the power is off.  
3. Remove the knockout on the junction box with needle nose pliers.  
4. Strip the plastic outer sheath of the NM cable to where you can see about six inches of exposed wire.  Use wire strippers to remove 3/4 inch of insulation for each of the wires.
5. Push the wires through the electrical wire connector.  Tighten clamp screws where the clamp tightens over the sheathed section of the NM cable, but not over the exposed wires. 
6. Push the wires through the knockout and secure the electrical wire connector to the junction box with a lock nut.  The lock nut should be included with the water heater.
7. The ground wire should be wrapped around the ground screw. Tighten it down.  
8. Take the black wire from the feed circuit and one wire from the water heater (either wire will do).  Twist them together.  Secure with a wire connector. Wrap electrical tape over the insulation so you can tell it is a current carrying line.  Do this at the breaker, too.
9. Connect it to the other wire from the water heater like you did the black wire.  Note:  A neutral wire is not needed because the hot water heater wiring has a 240 voltage.  Therefore, the white wire is the “hot” wire.  
10. Put the junction box cover back on and turn the water supply back on.  Fill up the water heater with water.  
11. Once the water heater is completely filled, turn on the circuit breaker.

Electrical jobs tend to intimidate even the most confident “do it yourselfers”.  However, wiring a water heater can be a simple process if you take the time to shut off the power at the source and read the instructions carefully.

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Comments (1)

• |2011-05-19 12:52:56 Jason Gage  - 12 Gallon Water heater Electric
  Do i need to add a j-box in between the 12 gallon water heater and the breaker box?
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