How To Chose A Back Up Generator And Service Transfer Switch

22kW Generac Guardian Abode Standby Generator with 200A SE Rated ATS

The automatic transfer switch—or ATS—makes a standby generator system a fully automated and reliable source of power during a power outage.

An ATS controls power from a standby generator similar to the way a thermostat controls a home heating and cooling system. Simply as a thermostat turns the furnace or air conditioner on and off as needed to regulate temperature, the ATS supplies power from the electric utility or from the standby generator as required. Some Generator Transfer Switches manage the power to ensure that essential appliances are able to run every bit needed.

Not all automatic switches are the same and making the correct choice is an important conclusion.

Home Standby Generator Sizing Guide

Transfer Switch Overview

A Briggs and Stratton 100A SE Rated Whole Business firm ATS with Symphony Ii Ability Direction

A transfer switch controls the source of power. When an outage occurs, the ATS isolates the electric utility from the home and connects the generator. Afterwards the utility restores ability, the automatic transfer switch isolates the generator and connects the utility. Isolating the utility lines prevents endangering utility workers from unexpected loftier voltages. It also protects the generator from damage when power is restored past the utility.

Equally the proper name implies, automatic transfer switches work automatically. When the power goes out, they automatically switch from utility power to generator ability. A manual transfer switch requires someone to physically move the switch from the utility position to generator position. After the utility restores ability, the ATS moves the organisation back to utility power automatically.

Automatic Transfer Switches come in two main types. Ane contains merely the transfer switch and the included options. It manages the power source for a panel of circuit breakers which may serve an entire building or just a few essential circuits. The other blazon—often called a Load Center ATS—contains both the transfer switch and the circuit breakers the switch serves.

Automatic Transfer Switch Buyer's Guide

Managed Power

Kohler 14kW Home Standby Generator Arrangement with 200A SE Rated ATS

Most circuits in a abode or business organization are 120-volt circuits limited to fifteen or 20 amperes. A few appliances require 240 volts and as much every bit 50 amperes.

Managing the 240-volt circuits prevents overloading a generator. Because a 20-kilowatt standby generator supplies fourscore to 85 amperes at 240 volts, adding one or ii high-voltage appliances to the need tin create an overload condition.

An ATS with managed power can prevent the overload by allowing the 240-volt appliances to run only when power is available. If one key air unit is already running, and another wants to start, the managed power option forces the 2nd unit to wait until the kickoff stops.

Did You Know that manufacturers often bundle an ATS with an Air Cooled Generator? The package saves you money on the purchase and simplifies installation.

Other managed loads include electric water heaters, well pumps, electric ranges, or electric dryers. These high voltage loads are often managed by their priority or importance.

Benefits of an ATS and Standby Generator Arrangement

Service Entrance Rating

The National Electric Lawmaking is Published by the National Burn down Prevention Clan

According to the National Electrical Code, a service entrance must contain a main disconnect. The service-panel'south main circuit breaker performs this part in many homes. A separate main disconnect in its own panel is incorporated in temporary buildings or in some jurisdictions.

The main disconnect has requirements that exceed the capability of common excursion breakers. In order to act as service entrance equipment, a transfer switch must contain these requirements into its design. The Service Entrance (SE) rating allows a transfer switch to supercede the existing equipment already performing this role, which simplifies installation and operation.

What is the National Electrical Code?

Current Rating

Kohler 12kW Standby Generator Packet Includes a 100 Amp 12-Circuit Load Center ATS

Automatic transfer switches must safely deport their maximum rated current whether the current is coming from a generator or from the electrical utility.

Fifty-fifty if the generator installed can simply supply 80 amperes of current during an outage, an ATS installed as a service entrance in a dwelling with 200 ampere utility service must safely handle 200 amps of current, fifty-fifty if the home never uses that much.

Conversely, if an ATS will but serve a limited number of circuits and operates equally a sub-panel, it only requires a rating that volition handle the maximum current possible. A 50-ampere circuit breaker in the main panel can feed a 50-ampere ATS during normal operation as long equally the generator's main breaker is besides 50 amperes or lower—neither the utility nor the generator can supply the switch with more fifty amperes.

Understanding Watts, Volts, and Amps

ATS Choices

Cummins Power Generation RS20AC Home Standby Generator Package with 200-Amp SE-Rated ATS

Most manufacturers supply automatic transfer switches designed to work with their standby generators. Each incorporates pattern features specific to the generators they manufacture. Choosing a transfer switch that was manufactured for employ with a specific generator brand and model guarantees it will work as expected.

Manufacturers often parcel standby generators with an ATS. If you plan to purchase a 22-kilowatt standby generator for a home with 200-ampere service, selecting a package with a 200A SE-Rated Automated Transfer Switch and 22-Kilowatt Standby Generator is probably your best option. The features provided by the generator and by the transfer switch volition govern your conclusion.

Domicile Standby Generator Installation Guide

Updated August 3, 2018