What Size Breaker Does A 4500 Watt Water Heater Need?

If you’re thinking to install any type of device that requires electricity, you should keep in mind that your circuit breaker can handle only the limited amount of power required by the appliance. Circuit breakers are safety devices meant to obstruct the flow of electricity in case of overloads or short circuits. On the other hand, a water heater is a device that requires a constant flow of electricity, which means that there are specific requirements for your circuit breaker. In this article, we’ll explain what type of breaker is required for a 4500W water heater. So, let’s start!

What Size Breaker for 4500 Watt Water Heater? A 4500-watt water heater requires a 30-amp circuit breaker. Although this varies from state to state, the National Electrical Code states that the constant current of an appliance can only load up to 80% of the breaker’s maximum amperage. This is stated in the 125% rule (210.19 (A) (1) of the NEC).

The 125% rule isn’t as complicated as it sounds, as you’ll see in the next chapter. We’ll teach you how to calculate the required amperage of your breaker. However, if you’re still unsure how to do this, then we recommend to contact an electrician, and he will do this job for you.

How To Calculate The Proper Size Circuit Breaker?

To calculate the right breaker size for the circuit, simply divide the wattage of your device with the voltage and then multiply it by 125% (1,25 in decimal numbers). For example, if the wattage is 4500 and the voltage is 240, the divided number is 18,75. Next, be sure to multiply 18,75 by 1.25 = 23.4 amps.

Since there isn’t such thing as a 23,4 amp breaker, simply round it to the closest higher size of a breaker, for example, 25 and 30 should be a good choice. The 125% rule only applies here because the water heater is a device that requires constant current.

On the other hand, devices that do not require constant current (noncontinuous loads), can use the full amperage of a circuit breaker. Continuous load appliances can only use 80% of the amperage, which results in the need for greater amperage. For this reason, the 125% rule was applied to ensure that by increasing the circuit breaker’s total amperage, you can ensure that only 80% of it is used.

How Many Amps Does A 4500 Watt Water Heater Have?

The water heater that has 4500 W has around 18.75 amps (as we calculated above). That number must be multiplied by 125%, and then we’ll get around 24 amps, which are needed to run a water heater. This means that your circuit breaker will have to be at least 30 amps.

Still, you’ll need to be careful what else you’re plugging into the same circuit not to overload it. If your water heater is the only connected device, then 25 amps should do just fine, as we’ve shown above.

What Breaker Size Is Required For a 4500 W Water Heater?

The circuit breaker most professionals would recommend is a 30-amp dual breaker with either metallic or non-metallic wire. It is also recommended that you dedicate a whole circuit to a device such as a 4500-watt water heater for safety reasons. The circuit should also be 240 volts. You have to keep in mind both the voltage and the wattage when calculating the required amperage of your circuit breaker.

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How To Determine the Right Circuit Breaker Size?

Well, as was mentioned earlier, only 80% of the full amperage (a max. electric charge that a breaker can endure) can be used when it comes to devices that require a continuous current. This is, of course, mandatory according to the NEC and thus all electricians need to stick to this rule. If the rule isn’t followed, it could result in the breaker tripping and obstructing the flow of electricity.

This rule is only applied to devices that require a constant and continuous current flow. This means that each appliance that operates without interruptions daily, such as a water heater, requires a breaker that will only work at 80% capacity.

Essentially, the 80% rule is another way to look at the 125% rule. One states that only 80% of the breaker’s maximum capacity should be used, whereas the other states that the amperage of your breaker should be 125% more than the amperage one calculates when dividing the wattage by the voltage.

For devices that do not work all the time, this rule doesn’t apply. To be more precise, the breaker can use 100% of its capacity for devices that do not require a continuous flow. Water heaters do not fit in this group of appliances.

What Wire Size Is Required For A 4500 Watt Water Heater?

Due to the constant flow of electricity through wires, electrical wires should be of a bigger gauge. Since the size of the wire correlates to how quickly the wire heats up in addition to the constant flow, your wires might cause trouble if they aren’t the correct size.

Depending on the wattage of your appliance, in this case, the water heater, be it 4500- or 3800-watt, the wire size should differ. If your heater is 4500 watts, the wire should be a metal-clad or non-metallic two-conductor 10-gauge wire. If water heater has 3800 watts, a 12-gauge two-conductor wire will do just fine.

Furthermore, since a water heater runs on 240 volts, a double-pole circuit breaker is needed for maximum safety. This is because the voltage required for a standard water heater is double the usual amount (120 volts). A double-pole circuit breaker will ensure that the doubled voltage won’t cause any issues even if one of the wires is faulty since the other one will send a signal and trip the breaker to stop the flow.

Is It Possible To Replace A 3500W With A 4500W Water Heater?

No, it’s not possible to replace a 3500W water heater with a 4500W. That is if you don’t plan on replacing your entire system, which includes breakers, wires, and circuits. The other way around works just fine, though. You can easily set up a lower-wattage water heater instead of a higher-wattage one since the system won’t be overloaded.

There are some downsides to using a less powerful water heater. It can only heat as much water per hour. For example, a 4500-watt water heater heats up to 40 gallons of water per hour. Its weaker counterpart heats only up to 30 gallons.

Is It Better To Have A Higher Watt Water Heater?

A higher-wattage water heater can heat up more water in an hour, but the water won’t be any hotter than the one heated by a lower-wattage heater. There will simply be more hot water for you to use.

It all comes down to the amount of hot water required by your household. People who live alone probably don’t need 40 gallons of hot water per hour, and a lower-wattage heater will work just fine in your case. On the other hand, opting for a higher-wattage heater isn’t a bad idea if you have an entire family living in one household.

How Many Watts Does My Water Heater Need?

It all depends on your household. The more powerful models stand at around 4000 watts. Water heaters are meant to operate anywhere between an hour and a half and three hours per day in order to keep your water hot at all times.

But when it comes to wattage itself, it would be best to decide with some numbers in mind. Check how much hot water you and your family use daily, and then opt for the right water heater model. If you use more than 20-25 gallons, getting a 4000- or 4500-watt water heater should do the trick.

Is It Better To Get A 20A or 30A Circuit Breaker?

It’s hard to say which is better since it depends on the wattage of your water heater. A 4500-watt heater simply cannot run with a 20-ampere circuit breaker. The minimum amperage of your circuit breaker should be 23 amperes. Circle this to the closest existing breaker size, and you get 25 amperes. Acquiring a 30 amp breaker is still recommended to ensure there aren’t any issues.

You also need to ensure you are using the correct wiring when connecting the 30 amp breaker. A 12 gauge wire simply cannot take the power of a 30 amp breaker, it will heat up quickly and cause issues. The recommended size is a 10 gauge wire with 2 conductors. Although, in theory, a water heater could run with a 20-ampere circuit breaker and a 12-gauge wire, since the heater requires only 18.75 amperes, you would be breaking the NEC and also endangering the safety of your household.

For those who want to learn more, be sure to read Can You Paint An Electrical Box In Your Yard?

FAQ: People Also Ask

What size breaker do I need for a dual 5500-watt water heater?

A 5500-watt water heater requires a 30-ampere circuit breaker. This can be easily calculated by dividing the wattage (5500) with the voltage (240) and multiplying the number by 1.25. The number you would get is 28.64 amperes, which can be circled to 30 amperes.

Can I use a 20 amp breaker for the hot water tank?

You can, but you would be breaking the NEC, which states that only 80% of the breaker should be used for devices that require a continuous flow of electricity. Simply install a 30-ampere breaker to make sure that your installations are safe.

How many amps does a 50-gallon water heater pull?

Since a 50-gallon water tank amounts to a water heater of about 4500 watts, 18.75 amps are required. But due to the NEC regulations, the breaker used should run 25 amps.

Final Thoughts

A 4500-watt water heater requires 18.75 amperes to run. Still, according to the National Electrical Code, each device or appliance that requires a continuous and constant flow of electricity can only use 80% of the circuit breakers’ amperage.

This correlates with the 125% rule, which can help you calculate the required amperage of your breaker (wattage/voltage×1.25=required amperage). Also, if you don’t want your wires to overheat, use a compatible wire, for example, a 30-ampere circuit breaker requires a 10 gauge wire with double conductors.