Water Heater Bonding Wire Size

4 copper wire is sufficient for service not exceeding 200 amps.

Water heater bonding wire size. Some large heaters draw up to 50 amps requiring 6 gauge wire. A bonding wire is an external part that is attached to the water heater. This is from a different table of sizes for grounding electrode conductors as opposed to ground wires from main panel to subpanel grounding conductors. 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.

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. It typically has two brass clamps with a thick copper wire strung between them. For 200 amp service use a 4 gauge copper wire from the panel to the water pipe within 5 feet of where it enters the house and also between where it enters and the meter. Houston home inspector discusses bonding of water heater.

One clamp is placed on the cold water pipe while the other goes on the hot water pipe. By bonding the hot water pipe to the cold water pipe at the water heater it is thought that this helps to ensure that the entire plumbing system will be electrically grounded. For 200 ampere service you ll probably be using 4 awg copper or 2 awg aluminum. The system amperage usually 100 or 200 amps determines the required gauge of the bonding wire you need.

The bonding jumper is to be sized using table 250 66. For gas piping you can bond it to the same things as mentioned for water piping. Check with your electrical inspector if you want to use wire smaller than 4. Now lets consider this water heater circuit installation.

It should be noted that the national electric code does not require a bonding wire on a water heater. The water bonding jumper from the panelboard or switchboard is sized the same as an equipment grounding conductor in accordance with table 250 122.