Electric Water Heater Wire Size

Some large heaters draw up to 50 amps requiring 6 gauge wire.

Electric water heater wire size. Yes an electric water heater is a dedicated circuit. 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. Most residential water heaters have 4500 watt elements and require a circuit ampacity of 24 amperes.

The ground wire is attached to the green ground screw which is in the same wiring junction box compartment which is built into the top of the water heater. Electric water heaters require a 240 volt dedicated circuit which serves only the water heater and no other appliances or devices. My personal preference for electric water heaters is to use an 80 gallon model. That means no less than 10 copper conductors and either a 25 or 30 ampere circuit breaker.

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. 2 1000w 1 1500w 240v heaters 3500 watts total. These 3 heaters would require 12 2 wire and a 20 amp 2 pole breaker if they were to all be placed on the same circuit. Understanding water heater wiring.

When placing multiple heaters on a circuit do not exceed the wattage listed for the corresponding wire and circuit breaker size. 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.