Water Heater Amperage Draw - Web water heater watts / voltage = amps drawn. 4500 / 240 = 18.75. For example, if the rating plate states that the water heater is 240 volts. Web amp draw (4500 watt heater) = 4500 watts / 240 volts = 18.8 amps. If you need to know what size breaker for a 30 gallon water. Web p (w) = 1 a * 120 v = 120 w. Web the amp rating will be listed in amps or as a numerical value followed by the letter ‘a’. The example shows us that one amp is 120 watts, in this equation. If you have a 4500 watt water heater running on a 240v ac outlet, it will use 18.75 amps an hour. In short, most commonly sized water heaters use 18.8 amps when running at 100% output.
Web water heater watts / voltage = amps drawn. 4500 / 240 = 18.75. If you have a 4500 watt water heater running on a 240v ac outlet, it will use 18.75 amps an hour. The example shows us that one amp is 120 watts, in this equation. In short, most commonly sized water heaters use 18.8 amps when running at 100% output. For example, if the rating plate states that the water heater is 240 volts. Web the amp rating will be listed in amps or as a numerical value followed by the letter ‘a’. If you need to know what size breaker for a 30 gallon water. Web amp draw (4500 watt heater) = 4500 watts / 240 volts = 18.8 amps. Web p (w) = 1 a * 120 v = 120 w.