Installing a backup generator for your home is a fantastic investment that should ensure you continue to have power any time an outage or blackout occurs. Backup generators are different from portable generators since they are permanently installed and directly wired to the building’s electrical system. As soon as the power goes out, a device known as an automatic transfer switch will immediately signal the generator to run and your power will be restored within just a few seconds. While a backup generator can be extremely useful, it will only work as it should if it’s the right size for your home.

Why Choosing the Right Size Backup Generator Is Important

It’s essential that your backup generator is sufficiently powerful to meet all of your most important electrical needs during a power outage. Most generators allow you to prioritize certain electrical loads, which means you don’t always need to go with a generator that is large enough to power 100% of your home at the same time. Nonetheless, you still want to make sure that the generator is large enough that it doesn’t get overloaded when your air conditioning or heating comes on or when using any other large appliances.

Most modern generators have an overload protection feature. This feature is essentially an internal circuit breaker that will trip and temporarily disconnect the generator from the home’s electrical event should an overload ever occur. The overload protection feature is important since a minor overload can shorten the life of the generator, and a major overload could cause the generator to overheat and suffer serious damage or completely burn out.

Ensuring that your generator is powerful enough that it doesn’t get overloaded will prevent the circuit breaker from tripping and your home suddenly losing power again. If the breaker did ever trip, you’d need to go outside to the generator and manually reset it. However, if you continued trying to power the same things and didn’t correct the overload, you’d end up with the breaker continually tripping and the generator never working as it should.

Calculating Your Home’s Electrical Load

Sizing a backup generator is generally always something that you will need an electrician to do. The only way to accurately determine what size generator a home needs is for an electrician to perform an electrical load calculation. This involves adding up the total kilowatt-hours of electricity needed to power the home’s lighting and all of the important appliances and electronic devices you think you may need to use during a blackout. Exactly which appliances you may need can vary. Nonetheless, the most important things are usually air conditioning and heating, refrigerators and freezers and the home’s water heater, stove and oven if they are electric. You may also want to ensure you have enough power for at least one TV and maybe your computer.

It’s unlikely that you’d ever need to have all of your lights on at the same time as your refrigerator, freezer, HVAC and other major appliances are running. This is especially true considering that appliances like refrigerators, freezers and electric water heaters only run sporadically. In most cases, an electrician will first determine the power draw of your central AC system and use this as the baseline when sizing the generator. The only exception is if your home has an electric furnace or some other type of electric heating.

The reason that they will start with the air conditioning or heating is that the HVAC system typically draws much more power than anything else in the average home. Once they’ve determined how much your HVAC system uses, they will then add in at least a few extra kilowatt-hours to the calculation so that the generator can still also power your lighting and at least some of your appliances any time your AC or heating is running.

When calculating the electrical needs of your HVAC system and other major appliances, the electrician will always look at the starting load and not the running load. The starting load for central air conditioners and some other major appliances like refrigerators and freezers is usually at least three times higher than the amount of electricity they use when running.

A 3-ton central AC or heat pump typically uses anywhere from 2.5 to 3.5 kWh of power when running, which means the starting load for a unit this size is likely at least 7.5 to 10.5 kWh. This also doesn’t factor in the HVAC blower, which usually has a running load of around 0.5 kWh and a starting load of around 1.5 kWh. Depending on how efficient your AC is, your backup generator would potentially need to supply somewhere between 9 and 11 kWh just to turn your AC on without being overloaded.

For an HVAC system with a 3-ton AC, most electricians would recommend at least a 14 kWh generator so that you can keep your air conditioning and other things powered at the same time. If you have a 5-ton AC or heat pump, you’d likely need at least a 20 kWh generator.

How Load Management Works With a Backup Generator

Load management is a process that allows you to program a backup generator so that it prioritizes certain electrical loads. Instead of just attempting to power everything in the home at once and potentially getting overloaded, the generator will always send power to the priority loads first. In most cases, your HVAC system and lighting will be the first priorities. If your air conditioning or heating needs to run when the generator first comes on, it will always power it first. Once the system is on and operating at its running load, the generator will then start powering the secondary priority circuits and appliances such as your refrigerator and freezer. Load management is important since the starting loads for your HVAC system and other major appliances could easily overload the generator if it tried to turn everything on at once.

Most generators also have another feature known as load shedding, which can allow you to go with a slightly smaller generator than you would otherwise need. Any time your HVAC system needs to turn on again, the generator may end up temporarily “shedding” the lower priority loads. This means that it would stop powering some circuits or appliances for a short time until the HVAC system was fully up and running to again ensure it doesn’t get overloaded.

HR Phoenix is a family-owned company that offers exceptional electrical services to customers in Richland Hills and throughout the Dallas-Ft. Worth Metro area. We install backup generators for residential and commercial buildings, and we’ll take care of everything from the electrical load calculation to installing the automatic transfer switch and testing the generator. We can also take care of your routine generator maintenance or repair needs to ensure your unit always works when you need it to. Our team also specializes in all other electrical services including rewiring, panel upgrades, repairs, EV charging station installation and more. No matter what type of electrical service you need, you can also count on us to provide a free, upfront estimate. Contact us today to schedule a consultation and let us ensure that you get the right backup generator for your home or business.

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