Hello, I'm Kimi, a specialist in electrical engineering and home appliances. When it comes to water heaters, one of the key considerations is the electrical requirements, including the amperage of the water heater. Let's delve into the specifics of a 40-gallon water heater and its amperage.

Firstly, it's important to understand that the amperage of a water heater is directly related to its power consumption and the electrical supply it is connected to. The formula to calculate the amperage is quite simple: **Amperage (Amps) = Power (Watts) / Voltage (Volts)**.

Now, let's consider the reference you've provided. It mentions a calculation for a water heater with a power rating of 4,500 watts and a voltage of 240 volts. Using the formula, the amperage would be 4,500W / 240V = 18.75A. However, the calculation then multiplies this by 1.5, which seems to be an application of a safety factor or possibly a rule from an electrical code like 422.11(E). This would result in 28A, and the suggestion is to use a 30A breaker as the proper size.

Another piece of information you've provided talks about 40 Imperial gallon electric water heaters, which are equivalent to approximately 50 US gallons. These heaters have 3,000 watt elements and are breakered at 20 amps, using #12/2 wire.

It's crucial to note that the actual amperage of a water heater can vary based on several factors, including the power rating of the heating element, the voltage of the electrical supply, and local electrical codes. The calculation provided seems to be a specific case rather than a universal rule.

For a 40-gallon water heater, if we assume a common power rating of around 3,000 watts (which is a typical value for residential water heaters) and a standard voltage of 240 volts in many regions, the calculation would be 3,000W / 240V = 12.5A. This means that a 15A breaker would typically be sufficient for such a water heater, considering a safety margin.

However, it's always best to consult the manufacturer's specifications for the exact power rating and recommended breaker size for your specific water heater model. This ensures compliance with both safety standards and local electrical codes.

To summarize, while the calculations provided give us a general idea, the actual amperage and breaker size for a 40-gallon water heater should be determined based on the heater's specific power rating and the electrical supply it will be connected to. Always refer to the manufacturer's guidelines and consult with a licensed electrician to ensure safe and proper installation.

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4,500W/240V = 18.75 x 1.5 = 28A ( next size up rule per 422.11(E) ) 30A breaker is the proper size. Paul. Our 40 Imperial (Canadian) gallon electric hot water heaters (roughly equivalent to the US 50 gal units) have 3000 watt elements only and are breakered at 20 amps while using #12/2 wire.Feb 4, 2007read more >>