Electric water heaters require a 240-volt dedicated circuit. This requires a 30 amp double pole breaker.
Now, that is probably just a bunch of words that have no meaning to you. But we promise, it is easier than it looks.
Below, we show you how to calculate what size breaker your water heater needs and why breakers are so important.
So, before you spend a small fortune on a professional plumber you can find out what size breaker you need for yourself!
What Is A Circuit Breaker?
When your water heater is running, voltage is pushing electrons through the wire and can produce a large amount of heat.
When there is excess heat on the wires, it can melt the covering and cause a fire. So, in order to prevent that from happening a device was created.
When there is too much electricity flowing through the circuit, a circuit breaker “trips,” interrupting the electrical flow from the source to the heating components.
In other words, it cuts off the water heater’s power supply, protecting both your house and the integrity of the equipment.
Without a breaker, you are putting yourself, your family, and your home at risk of an electrical fire.
Getting To Know Your Water Heater
Before you begin touching wires and buttons, get to know your water heater.
Once your electric water heater has been delivered, take the time to check the amperage.
You may even want to do this before you purchase the specific water heater.
Either before you purchase your water heater or when it arrives, there are 3 things that you should check straight away:
Wire Size: Knowing which cable type and breaker size work with your hot water heater is crucial. Your heater and breaker may be put in greater danger due to an incompatible size or defective wires that have been reused.
Voltage: Your boiler’s volts are crucial to a functional circuit. Depending on the size and wattage of your tank, you can connect an ordinary heater to a 220 or 240 Volt outlet.
Wattage: Knowing the wattage of your water heater will make it easier to determine the power it needs and the breaker it requires.
Calculate Breaker Size: The Formula
Unfortunately, knowing what breaker size your water heater needs is going to require some mathematics. It is a simple calculation as you already know the wattage and voltage of your water heater.
The formula is: I (amps)= P (WATTS)/ V (volts).
An example is that your water heater has a tank of 3,000 watts and it requires 120-volt power. In order to determine the amperage the calculation would look like this:
I=P/V
= 3000 watts/ 120 volts
25 amps
Now that we know the amperage of the water heater, we can begin to determine the breaker size.
The National Electric Code (NEC) has established a rule stating that you must maintain 125% of the maximum continuous load.
The safe quantity for your electric water heater breaker size must be determined in this phase.
Continuing with the same example, this would look like:
125% x 25 amps
= 31.25 amps.
Now, you can purchase the closest amp size which would be 35 amps. Anything lower than this will constantly trip the circuit and cause your water heater to malfunction.
Measures To Take Before Purchasing A Circuit Breaker
When you are browsing the options for the best water heater, there are a few things to consider.
Especially the amp difference between the breaker and the heater. Getting the wrong size of circuit breaker can have serious consequences.
Expect your CB to trip often if the breaker is too small for the ampere needs of the water heater.
Additionally, repeatedly turning on and off the heater can harm its internal components.
Please update the breaker if necessary and avoid sharing the circuit with other appliances if you have a water heater.
It’s not always true that a breaker with a larger amperage than anticipated is safer for the heater.
Your breaker will ignore an overload or short circuit that occurs in the tank at an unforeseen time, providing zero protection.
However, using the formula above will provide you with enough room in your breaker to support the power needed by the heater without the breaker ignoring the overload.
Giving you protection from electrical hazards.
Takeaway
Finding the right size circuit breaker for your water heater can seem complicated.
However, with the right information, it is actually rather simple.
Remember when selecting your water heater to take note of the wattage, voltage, and wire size.
With this information, you can use the I=P/V formula that will give you the amperage which can then be used to determine the right breaker size.
Always round up to the nearest breaker size to allow room for heat to travel through the breaker.
Or else you can end up with an electrical hazard or fire!
Frequently Asked Questions
What Is The Difference Between A 15 Amp And A 30 Amp Water Heater?
The reduced components make the biggest difference. Instead of the typical 4,500-watt elements found in conventional electric water heaters, the 15 amp variant uses 2,500-watt elements.
The 15 amp model’s first-hour rating is 54 gallons per hour. The first-hour rate for the 30 amp variant is 67 gallons per hour, in contrast.
Can A 20A Amp Breaker Be Used For A Hot Water Tank?
Overall, a 30A breaker will be needed for the majority of conventional 4500-watt water heaters.
A 20A breaker may be adequate for smaller hot water heaters. The standard breaker size for larger heaters (such as 100-gallon models) is double 30A.
Can A 13A Plug Be Used For A Water Heater?
No, a water heater requires at least a 15A power source.
Using a 13A power socket may result in your wires overheating, melting, and leading to a short circuit or electrical fire.
Hi everyone! My name is Jason, and I am the founder of HeaterWise.com. Having run my own business as a Heating Engineer for 21 years, I have picked up a few things along the way.
I wanted to create Heater Wise as a place where anyone could come, from far and wide, to find the information that they need.
I hope you will join us here at Heater Wise, to get started on your own journey, to expand your knowledge, and make the best heating choices for you and your family.
