Amperage Assessment for Major Appliances

Ask a Home Inspector?

In almost every Myrtle Beach Home Inspection we find an incorrect amperage rating (size of circuit breaker) in the main electrical service panel for several major appliances (yes, several). The primary reason for this is the electrician does not coordinate with other trades persons to confirm the amperage requirements on any particular appliance and installs the circuit breaker he feels will be suitable for that particular appliance.

There are many problems with this scenario which we will discuss in this Ask a Home Inspector. In this post we will look at how to assess the problem, calculate the appropriate amperage and correct the problem.


Every appliance has an efficiency factor based on the design and engineering of that particular appliance. If an appliance requires a certain amount of electrical current (Amperage) to function at its most efficient state, we need to make sure the power requirement (Wattage) of the appliance is designed to suit and visa versa.

If a major appliance has a dedicated breaker in the electrical breaker panel that is higher than the allowable current (Amperage) then the appliance will draw more power (Watts) than it is designed to do so, and it will shorten its lifespan. However, if the major appliance has a dedicated breaker that is lower than the allowable current then the appliance will have to work harder than normal to be its most efficient, thus shortening its lifespan.

These tags that we see on all of our major appliances are a rating of efficiency based on the electrical design and engineering of that particular appliance.

Assessing the Problem

If a major appliance has malfunctioned or stopped working all together, the likelihood of the problem being at the electrical panel is probable. The first thing to do when assessing the correct amperage at any appliance, is to find the maximum breaker rating for the appliance.

After you locate the maximum breaker rating for the appliance then cross reference the size of the breaker inside the electrical panel. These 2 figures should be exactly the same.

Exactly the same figure is what you’re looking for.

If you cannot locate the maximum breaker rating on the appliance then you will have to do a calculation using the wattage of the appliance. The wattage of any appliance can be located online with the manufacturers specification label model and serial number. They look something like this.

Before we move forward with calculating the appropriate breaker ratings for any particular major appliance based on wattage, I’ll explain how a circuit breaker works.

A circuit breaker is essentially a dam for electricity, the breaker is always only allowing a specific or maximum amount of power (watts) and current (amps) to reach a particular appliance. All circuit breakers installed in the electrical panel should have an over capacity factor of 20%, meaning that the breaker size should be at least 20% greater than the required amperage for the appliance to prevent the breaker from tripping during maximum power consumption. This calculation represents how to determine the correct amperage (breaker rating) for any appliance using the appliances wattage.

Wattage/ Voltage/ 80%= Required Amperage for appliance

We all know that there are two voltages in our homes: The first is 110 V for small appliances and for major appliances we use 110 V x 2 or 220 V . Knowing this, we can make a very simple calculation using the wattage indicated on the manufacturers specification label in order to determine the correct Amperage. Let’s use the example below to determine the amperage requirement for a water heater.

Water heater wattage= 4500 Watts

Water heater voltage= 220 Volts

Required Amperage= 4500 Watts/ 220 Volts/ 80%= 25.56 Amps

Now that we have figured out the required amperage for the appliance we need to establish the size of the breaker to be installed in the Electrical Panel. We do this by simply rounding the required amperage up to the next 5 amperage increment.

25.56 Amps rounded up to nearest 5 Amp increment= 30 Amp Breaker

In almost all cases, the Myrtle Beach Home Inspector will find anomalies between the required breaker rating and the actual breaker size in the electrical panel. Because of this, the Home Inspector will always perform these calculations to ensure the home buyer or seller understands the importance of the issue. We will also explain how to take corrective action by replacing the breakers with the correct sizes to match what is indicated on the appliance.

Here is a list of all the major appliances in the home with there respective breaker rating ranges and what you are more likely to find in order to calculate the appropriate breaker rating.

Now that you have all the information you need to make sure that the major appliances of the home are running as efficiently as possible, you can advise homeowners on the importance of this issue. You may also want to go check your electrical panel in your own home to make sure this major concern was not overlooked by your Myrtle Beach Home Inspector.


Me and my team at LAB Home Inspections hope you really enjoyed this article!


If you have specific questions about your home, or would like to schedule a home inspection, please contact Darren directly:

Darren Dawson, Certified Master Inspector (CMI)®

Myrtle Beach, SC

(352) 665- 9900

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