What Size Standby Generator Do I Need

You've decided that you're ready to invest in a standby generator, or a permanent unit capable of powering your essentials during an outage.

Yous considered a less expensive portable unit or another depression wattage standby, only yous fear the smaller generator may not have the power you need to support your wattage.

Simply how much wattage do you actually demand— and what size dwelling generator do you need to fuel your firm-full of electronics?

We're here to help you lot cull the right size generator for your electrical needs.

How Many Watts Do You Need?

The first step in choosing your platonic home generator size is to make a list of all the electronics you'd like to power during the outage.

Jot down some bullets with the essentials first, such as keeping your refrigerator running, a few lights on and your Air conditioning pumping (hither in Florida, this is a must!). Adjacent to that, create a column of "nice-to-haves," like powering your hair dryer or microwave, etc. If yous'd like the luxury of having everything run as normal, acuminate your pencil and marking downwardly all the items y'all'd use in the result of a few-day outage.

Next to each detail you wrote down, jot downwards two numbers: the starting wattage and the running wattage of each item. These calculations are the amount of juice you need to go the device on besides as how much energy y'all'll demand to go on them powered.

Not certain how many watts your hot h2o heater or TV requires? Honda compiled a list of common household electronics to help you make up one's mind your generator wattage. Or, type in your apparatus blazon on Energy.gov to notice each device's wattage rating manually.

Generator Sizing Guide

Don't Forget Your Automatic Transfer Switch

At present that you accept a list of all the electronics in your business firm and their wattage requirements, yous can start doing some math. But first, permit's non forget to factor in your automated transfer switch (ATS), if you have one.

While some generators need to be manually turned on in the event of an outage, many standby units can find a disruption in current all on their own, and kick on automatically with the help of an ATS.

This switch needs juice to operate— commonly the equivalent of your breaker panel'south amperage. For case, if you lot have a 200-amp breaker panel, then you'll likely have a 200-amp switch to lucifer.

Since amps are not the aforementioned every bit watts, yous'll need to do a lilliputian conversion: watts = amps × volts.

Once you've determined the wattage of your ATS, tack that onto your listing and do some simple addition to discover your necessary wattage load.

Generator Sizing Guide

A Generator Sizing Scenario

Permit's walk through a fictitious situation to help you summate your habitation generator's wattage requirements.

Scenario 1:

The Smiths have very different ideas about what they would like powered during an outage.

Mr. Smith only wants to power the "essentials" and he made the post-obit wattage listing to keep his Fort Myers abode running in the outcome of a few-day outage:

Electronic	Wattage
two light fixtures	175W (far less if they are using LED bulbs)
Electric h2o heater	4,000W
Primal A/C	iv,500W
Refrigerator	i,500W
Phone and tablet charger	50W
TOTAL WATTAGE:	10,225W

Scenario ii:

Mrs. Smith, however, wants to savour more luxuries if the power were to be out for many days in a row! She doesn't desire to be without entertainment, her kitchen or basic home care tech like her washer and dryer.

Here's Mrs. Smith's list:

Electronic	Wattage
15 calorie-free fixtures (all the lights in their abode)	ane,225W
Electric water heater	4,000W
Central A/C	four,500W
Refrigerator	i,500W
Phone and tablet charger	50W
2 laptop computers	150W
Microwave	1,000W
Stove/range	three,000W
Dishwasher	1,500W
Clothes washer and dryer	3,000W (collectively)
3 LCD TVs	450W
WiFi and cable modem	40W
Garage door opener	2,300W
Total WATTAGE:	22,715W

Now that they've determined their wattage in "watts," the Smiths must convert their power requirements into kilowatts.

Watts vs. Kilowatts

Home generators are sold in measurements of kilowatts, which is why the Smiths have to do i final conversion to observe the correct home generator size.

Google provides a prissy tool for converting W or kW when you lot search watts vs. kilowatts. Using Mrs. Smith'south example above, nosotros tin can encounter that 22,715W would require 22.715 kilowatts. Then all you have to practise it swap your comma for a menstruum, as it'south a 1,000 to 1 ratio.

If Mr. Smith had his way, he'd simply need a 11 or 12 kW generator to ability his x,225W load (it's ever safer to add an extra kilowatt or ii just in example!). If Mrs. Smith got to cull, they'd demand a 25 kW dwelling house generator.

And that's it! Now you know how to calculate your home generator wattage requirements and choose the right sized generator for your electrical needs.

More Decisions: Fuel Type, Brand & More

Even though you've figured out how to make up one's mind your abode's generator wattage requirements, that's not all you accept to consider before purchasing a new ability unit.

Practice you lot know if yous'll get a propane vs. gas generator? How about much your generator cost will increase as your wattage requirements likewise increases? Then in that location'south some other big decision: which brand do you choose?

We discuss all of these things and more on our Choosing a Home Generator page. Simply click the image below for free advice from your friendly Southwest Florida electricians at SWFL Electric.

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