Previously, we shared a simple way to map out your home’s electrical system. However, if that was too difficult, or you do not feel comfortable doing so, contact our experienced residential electricians to do the job. This week, we are going to share how you can calculate circuit loads.

You have mapped out your home’s electrical circuits, and now, you can tell which circuit powers each device, or appliance. Next up is calculations. It is very necessary and useful to know how much power your devices are using.

Electricity education recap:

Before we get started, here is a quick refresh on how electricity works. Electricity is measured in watts. For example, a one hundred watt light used one hundred (100w) watts of electricity. A watt is a product of voltage and amperage .

Voltage is measured in “volts”, and amperage is often seen as “amps”. To calculate the total load on a circuit, you must add up the wattage of all the devices on that circuit. Light bulbs and most small appliances have labels with a “w”.

Can this circuit carry this load?:

Be careful of touching lightbulbs after they’ve been on. Usually, you do not need to unscrew them to read the wattage. If the device is only labeled in amps, multiple the number of amps by one hundred twenty (120) volts. One hundred twenty volts is the voltage of standard circuits.

Include all appliances that are permanently wired to the circuit along with the plug-in appliances that you do not unplug very often. Many people do not unplug their coffee machine, toaster, stand up fan or blender every day.

Once you have the calculated load, compare the total wattage to the load rating of that circuit. The spruce says, “The circuits with ’15’ breakers are rated for 15 amps.” This means the maximum load rating of one of these circuits is eighteen hundred watts.

Example: 120 volts x 15 amps = 1800 watts

If you try to use more than eighteen hundred watts, you will overload the circuit. Is it all clicking now? If you overload the circuit, the breaker will trip for your safety.

Circuits with “20” breakers are rated for twenty amps and have a maximum load of two thousand four hundred watts.

Example: 120 volts x 20 amps = 2400 watts

Basically, compare how much electricity you are currently using, the wattage total and the load rating for each circuit. For example, if you have a  fifteen amp circuit serving lights and outlets in a living room area that provides five hundred watts for lighting, five hundred for the tv and cable box, and  two hundred watts for the sound system equipment, you will get a total of 1200 watts.

But if you plug in a vacuum while all of this appliances are plugged in, you will exceed the circuit breaker’s total fifteen hundred watt rating. Because of this circuit overload, you will cause the breaker to trip turning off the power.

For a good rule of thumb, do not exceed eighty percent of the maximum rated load. Refer to the vacuum example. For a fifteen amp circuit, the safe load is 1440 watts. For a twenty amp circuit, the safe load is one thousand nine hundred twenty watts.

Contact Sanford Electric Company II, Inc. for solutions to this issue. You may possibly need new wiring or a full-house wiring replacement. We will find your home’s solution. Come by next time for more on all things electrical.

Staff Writer