Water Heater Breaker Size

A 1500 watt heater on a 120 volt circuit thus needs a breaker of 15 6 amps.

Water heater breaker size. This happens because 20 amp from the water heater is more than 80 of the breaker capacity. Simply locate the appropriate water heater sizes on ecomfort using your information. The general rule of thumb is that circuit breaker size should be 125 of the ampacity of cable and wire or the circuit which has to be protected by the cb. This was fine for these heaters but most modern heaters are 4500 watts.

Instead you need at least 25 amp. 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. Wire a hot water heater with wire that s sized to accommodate the heater s current requirement. Some large heaters draw up to 50 amps requiring 6 gauge wire.

To determine the appropriate size of circuit breaker for single phase supply it depends on multiple factors like type of load cable material and environment temperature etc. Years ago it was not uncommon to have a 3000 or 4000 watt water heater fed with 12 s and a 20 amp breaker. Multiply the value for current by 125 percent to determine the size of the breaker you need for the heater. In the above example we would require a 15 6 amp circuit breaker for our us readers.

An acquaintance has an older mobile galvanized branch water lines and his water heater. So it won t work as effectively as it needs. Below we ve highlighted what size water heater you would need in our example of 6 5 gpm at a 63 f temperature rise. 40 gal 240v dual 4500w 18 75a connected to the circuit breaker panel double pole 40a breaker with a 12 20amp cable.

Multiply the current rating of the water heater with 125 now in order to choose an electric breaker multiply the current draw of the water heater with 125 per cent in order to determine the size of the breaker you will need. Once you have your total flow rate and the required temperature rise you can find the right size tankless water heater for your home.