Will A 12 000 Watt Generator Run A House?

Will A 12 000 Watt Generator Run A House?

When power outages strike, many homeowners ponder the capacity of their backup generators. A 12,000-watt generator sounds robust, but can it truly power an entire home?

A 12,000 watt generator is large enough to power a small to medium-sized home, as long as sensible precautions are followed. Managing which appliances run simultaneously and also exercising electrical conservation practices such as replacing halogen lightbulbs with low-powered LED units.

Dive into this article as we dissect the capabilities of a 12kW generator, analyzing its suitability for residential needs.

A 12 000 Watt Generator Will Run a House

A 12,000-watt generator, also known as a 12kW (kilowatt), is a powerful electrical unit that can power most small to medium-sized homes.

Before discussing how to “size” the electrical requirements of a home, let’s first look at the units of measurement that grade electric generators and home appliances.

Understanding Power Needs

Have you ever wondered why the following units of electrical measurement are used?

  • Your energy bill displays consumption in terms of kilowatt-hours.
  • Light bulbs are labeled in “watts.”
  • batteries commonly specify their voltage, such as 9 volts.
  • Devices like vacuum cleaners highlight the amps they draw.

So, why are there so many distinct electrical measurements?

Let’s break it down with a simple analogy.

Think of electricity as water atop a waterfall. As it reaches the brink, gravity influences its descent. The crest, where water pauses before its plunge, mirrors a battery’s negative terminal.

All these electrical metrics are interconnected. Knowing two allows you to derive the third.


Positioned at the waterfall’s peak, the water holds potential energy not yet set in motion. Similarly, voltage signifies potential energy, ready to drive an electrical current from the negative to the positive terminal.

Mathematically, it’s defined as Voltage = Watts/Amps.


When water descends, it accelerates under gravity until reaching terminal velocity. If we gauged its speed mid-fall, it would resemble the amperage in an electrical circuit. Technically, one ampere is defined as:

One ampere = 6.24 × 1018 electrons passing a point in one second.

And its relationship with watts and volts is Amps = Watts/ Volts.


Consider installing a turbine in the waterfall. The water’s force turning the turbine blades is akin to work. Knowing the energy potential (volts) and measuring the speed of water molecules (amps) lets us compute the force or “pressure” exerted, which is analogous to watts.

Learn More!!!  Can a Hammer Drill Be Used as an Impact Driver?

Watts can be influenced in several ways:

  • The water pressure decreases if the waterfall’s width expands, but the water flow stays consistent. Similarly, when voltage drops, the available watts to power a device diminish.
  • Boosting water pressure by increasing its flow rate will make more water spill over the edge, hence upping the force. Likewise, elevating the number of electrons in a circuit (amps) will raise the pressure.

Resultantly, the watts (pressure) in the circuit escalates and can power a larger motor or device.

In essence: Watts = Amps × Volts

By grasping these concepts, one can better understand the intricate dance of electricity that powers our everyday lives. It will also help you to size a generator correctly.

What does “12,000 Watts” Really Mean?

Let’s break this down:

A 12,000-watt (or 12kW) rating tells us how much electricity certain home devices use. When talking about batteries, there’s a bit more to it. A battery labeled 5kW-hour means it can give out 5kW in one hour.

So, if you use half of that power, it’ll last for 2 hours; if you use just 1kW, it’ll go for 5 hours.

Calculating Total Wattage

The measurement of Watts that an appliance, or series of appliances, draws is cumulative. This means that if one device draws 1kW and another 0.25kW, the total draw on the system is 1.25kW.

This is important to understand when calculating the size generator you need. The total draw of all the appliances that will run simultaneously must be added to assess the generator capacity.

For example, a house may have appliances that, in total, draw 15kW. The reality may, however, be that only 8kW of power is consumed at one time.

A simple breakdown of wattage, potential usage, and the implication of the number.

Comparing the 12,000 watts capacity to everyday power needs.

Learn More!!!  Generator Blowing White Smoke? Here’s What To Do

Allowing for “Surge” Wattage

Several home appliances use induction motors to run. These include

  • Fridges and freezers (The compressors)
  • Pumps.
  • Small fans.
  • Mixers.
  • Toys.
  • High-speed vacuum cleaners.
  • Electric shavers.
  • Drilling machines.

When an induction motor starts to operate, it draws (up to 3 times)  its normal running wattage. This means a fridge that consumes 450 watts may require up to 1.35kW to start running. This draw only occurs for seconds before the appliance runs.

With an appliance like a fridge, bringing the “surge” (or starting watts) into the calculation is important because the thermostat starts and stops the compressor regularly.

The good news is that the surge value is generally within the capability of a generator. The spec sheet will show a normal watt consumption (say 12kW) and a surge value, which is generally double (24kW) the normal value.

Appliances and Systems A 12,000 Watt Generator Can Power

To calculate the total watts drawn, list all the electrical consumers in your home. Add the following columns.

  1. Location (Kitchen, Lounge, etc.)
  2. Appliance description
  3. Normal watts consumed
  4. Surge Watts
  5. Likelihood of that item being run simultaneously with others.

For a one-bedroom apartment, the list may look like the following.

LocationApplianceNormal DrawWith Surge PowerStandby
KitchenAir Fryer150015000
Coffee Maker80014000
Cooker Hood20300
Deep Freezer19190
Electric Kettle120030000
Electric stove200020000
Fridge / Freezer1504000
Food Blender3004000
60W light bulb (Incandescent) *42402400
BathroomBathroom Towel Heater601500
Curling Iron25350
Electric Shaver15200
Electric Toothbrush Charger660
Extractor Fan12120
60W light bulb (Incandescent) *42402400
LoungeApple TV360.3
AV Receiver4504500
Ceiling Fan60700
Home Air Conditioner100040000
60W light bulb (Incandescent) *42402400
55 Inch LED TV1161160.5
BedroomCeiling Fan60700
Heated Hair Rollers4004000
Home Air Conditioner100040000
Night Light110
60W light bulb (Incandescent) *42402400
Fluorescent Lamp28450
Game Console1202000
Gaming PC3006001
Home Air Conditioner100040000
Home Internet Router5150
60W light bulb (Incandescent) *42402400
Utility RoomSteam Iron220025000
Vacuum Cleaner459000
60W light bulb (Incandescent) *42402400
Total Consumption17460329304.8
Realistic Consumption8117174873.8

In this scenario, the total is 17.4kW with a  maximum surge consumption of 32.9kW. However, as frightening as this may look, realistically, not all the devices would be turned on simultaneously.

The items marked in “bold” may be switched on together. Adding these values results in a total consumption of 8.1kW and a surge value of 17.5kW.

These values are well within the capability of a 12kW generator.

What Size Generator To Run A Freezer?

How To Run An Extension Cord From Generator To The Home


As shown, a 12kW generator is large enough to run a small to medium-sized house. With careful management of the home appliances used at any time, even a larger home can run on a 12kW generator.

Similar Posts