As a most needed appliance in harsh cold weather, we must feel reasonably used to having one water heater at home. Hence, we would not bother to calculate and ask how many amps does a water heater use. Only after the electricity bill comes out to do you know that it is essential to know these appliances’ amps.
The electricity bill for these units is quite expensive. You might not use it in a dry and hot season, but the bill can rise relatively high in cold weather. Therefore, it matters to know the water heater amps before using or buying one for yourself.

How Many Amps Does a Water Heater Use?
Besides the essential goal to save the costs of electricity bills, other things matter significantly for house owners on knowing the hot water heater amps. Those reasons are for safety matters.
Knowing the amperage of the water heater at home can prevent you from some danger of overloading the system on the unit. Preventing this from happening will make the safety of the household is in hand. Moreover, knowing that your house is safe is more important than anything, right?
Water heater amperage is decided on some factors. Those factors are the fuel type, heater type, capacity of the heater, and energy efficiency. Upon this knowledge, you could understand the amps too. Here are some points that might be useful:
- For the ground rule, a standard 4,500-watt water heater usually uses 18.8 amp. At the same time, the average water heater will work with 240 volts and 30 amperage breakers.
- A tankless water heater usually requires about 120 amperages to run. It is higher than the standard water heater that uses a water supply.
- The traditional water heater usually uses 30 amps to run, which is four times lower than the tankless water heater.
- A gas-electric water heater usually uses 12 amps and 115 volts.
How to Determine Breaker Size for Water Heater
Before determining the size of the water heater breaker, you must know a little information about it. Although it sounds trivial, this knowledge is crucial as it can affect your house’s safety. Here are a few things needed to size the breaker on your unit:
- You must use the water heater’s breaker only on this unit. Any other appliances could not use it.
- The breaker should be a double pole.
- You must use the right size of breaker to create safety.
- You need to buy a circuit breakers that can handle one-fourth more electrical than the unit requires.
Hence, here is the tutorial on how to determine the right size for the breaker:
- Collect the Right Information
The first thing you need to do is to collect information about the wattage and the voltage of your water heater. You can find this information in the manual, label, or internet.
- The Calculation
The next step is to calculate the maximum amps for the water heater. You can do this by using the equation:
Watts: Volts = Amps
- Calculate the Size of the Breaker
After that, you must multiply the Amps from the above equation by 125%. The number is the size of your breaker.
Choose the Ideal Residential Water Heater
Understanding the calculation of how many amps a water heater use can be helpful knowledge. It could help you to choose wisely the type of water heater and get the best option for your home. As a result, you could save energy as well as save costs. Therefore, you can feel comfortable without regretting it when the electricity bill comes out.
Heater Technician is a skilled author and water heater expert with years of experience in the field. He has authored several articles and books on various aspects of water heater installation, maintenance, and repair.