Water Heater Ground Wire Size

The wire supplying power from the breaker panel to your water heater will usually be a 10 2 romex cable blk wire hot marked white wire hot bare copper wire ground.

Water heater ground wire size. Now lets consider this water heater circuit installation. Still there are electricians and local building codes that vigorously defend the water heater bonding wire as a proper safety measure. The purpose of the ground is not to reroute full power delivery to ground but to eliminate the potential between ground and incorrectly energized appliance casings etc. This is from a different table of sizes for grounding electrode conductors as opposed to ground wires from main panel to subpanel grounding conductors.

Electric water heaters require a 240 volt dedicated circuit which serves only the water heater and no other appliances or devices. For example a 20 amp hot water heater needs 12 gauge wire a 25 amp hot water heater requires 10 gauge wire and a 30 to 40 amp hot water heater requires 8 gauge wire. At the water heater the black circuit wire connects to the black wire lead on the water heater and the white circuit wire connects to the white wire lead on the water heater. Understanding water heater wiring.

The required ground wire size is probably 6 awg see here even though power is supplied by 4 0. Wire a hot water heater with wire that s sized to accommodate the heater s current requirement. Many of the older 30 amp 240 volt dedicated water heater circuits consisted of a 2 wire with ground cable which consisted of a ground wire a black wire and a white wire and in these circuits the white wire was normally connected to the red wire of a 240 volt water heater however as described in the preceding the circuit must be positively verified first. Since a water heater has no outlet the cable will be run from the wall to the junction box on the water heater.

Some large heaters draw up to 50 amps requiring 6 gauge wire. You have stated that the calculated amperage load for 4500watt at 240volts is 18 75amps however nec article 422 13 states that the minimum circuit rating for a water heater must be 125 of the rated load so this 4500watt load requires a minimum circuit of 23 44 amps at 240volts. The circuit wiring typically includes a 30 amp double pole breaker and 10 2 non metallic nm or mc cable. The reasoning is that the metal casing on the water heater itself is thought to be sufficient to complete the continuous grounding path between the cold water and hot water pipes in the home.