How Big of a Generator Do I Need to Power My House? A Comprehensive Guide

Newbury, USA - September 29, 2022: Residential standby generator on concrete pad

This guide simplifies the process of calculating your wattage needs for powering essential appliances and choosing the appropriate generator size.

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How to Determine Generator Size

Residential standby generator on a concrete pad

Before purchasing a generator, it is crucial to determine the appropriate size that will meet your needs.

The size of the generator you need is determined by the total wattage and kilowatts required to power your home’s appliances.

To calculate the total wattage and kilowatts needed, consider the appliances you need to power and add up their wattage.

Appliances require a particular amount of power regardless of the voltage used.

For instance, a 600-watt appliance requires 2.5 amperes of current at 240 volts but requires twice the current, which is 5.0 amperes at 120 volts.

Generators are rated in watts or kilowatts, focusing on power rather than voltage.

Starting Wattage and Running Wattage

Generators come with two power capacity ratings: the maximum or starting watts and the continuous capacity or running watts.

Running watts refers to the power the generator can supply continuously without overloading. Starting watts are a boost of power available for a few seconds while starting a motor.

During startup, motors demand up to six times their continuous power, and the generator must handle this surge safely.

Determining Whole-House Generator Sizing

It is essential to determine the whole-house generator size that meets your needs to ensure that all your appliances are powered during an outage.

Some opt to power only lights, refrigerators, and security systems, needing a smaller generator than for the whole house.

Use of Generator Size Chart and Calculator

Generator size charts and calculators are available online and can guide you in determining the right generator size for your home.

You can input the total wattage of your appliances, including the starting wattage, and the calculator will give you the required generator size.

Types of Generators

When choosing a generator, you have two main options: traditional portable generators and inverter generators.

Recreational Inverter or Midsize Inverter Generator

Westinghouse Outdoor Power Equipment 4500 Peak Watt Super Quiet Portable Inverter Generator, Remote Electric Start with Auto Choke, Wheel & Handle Kit, RV Ready, Gas Powered, Parallel Capable

A recreational inverter or midsize inverter generator is ideal for powering essential items.

They are more fuel-efficient, quieter, and produce cleaner power than traditional portable generators delivering the same wattage. They are also more expensive.

Portable Models for Essential Items

Gasoline Generator Mobile Home

Portable models are more affordable and ideal for powering essential items during an outage.

They are suitable for short-term use and require frequent refueling.

Smartphone Apps and Fuel-Level Indicators

Some generators come with smartphone apps and fuel-level indicators that allow you to monitor the generator’s performance remotely.

These functions assist in controlling fuel consumption and avoiding overloads.

Basic Calculation for Generator Size

To determine the size of the generator you need, it is crucial to prioritize essential appliances such as refrigerators, security systems, and lights.

Calculating the required wattage involves adding up the total wattage of the appliances you want to power and factoring in the starting wattage for certain appliances.

Importance of Prioritizing Essential Appliances

Prioritizing essentials helps find the right generator size for home power during outages.

You can add other non-essential appliances if you have a larger generator or when power is stable.

Calculation of Required Wattage

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Calculating the required wattage involves adding up the total wattage of the appliances you want to power.

For instance, if you want to power a refrigerator (700 watts), a security system (50 watts), and lights (400 watts), the total wattage will be 1150 watts.

If you want to power other appliances, you can add up their wattage to get the total required wattage.

Factor in Start-Up Wattage for Certain Appliances

Certain appliances require more power to start than their running wattage. These appliances include air conditioners, refrigerators, and freezers.

It is crucial to factor in the starting wattage when calculating the required wattage to avoid overloading the generator during startup.

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