Home Standby Generator Transfer Switches: What They Are and How They Work

Never connect a generator directly to a home’s wiring! Once you’ve purchased your home generator system, hire a qualified electrician to install a transfer switch if you intend to connect the generator to your home’s electrical system. A transfer switch is the only proper and safe way to run a generator that is connected to a home’s electrical system. These switches should only be installed by professional and qualified electricians. Transfer switches have three selections: “generator”, “center off” and “utility”. This prevents you from having the generator and the utility power on at the same time, which could damage the wiring in your home. When installed properly, a transfer switch will prevent a back-feed to the utility lines which could prove fatal to anyone working on your neighborhood electrical line.

How An Automatic Transfer Switch Works
A transfer switch is the electronic “control center” responsible for managing the transition from utility service to your Home Generator System. When the power goes out, the transfer switch automatically senses the power disruption, signals the generator to turn on, and transfers power from utility to home power for the duration of the power outage. When utility power is restored, the switch senses that power has returned, shuts down the generator and resumes monitoring.

Which transfer switch do I need?
Selecting a transfer switch for your Home Generator System is dependent on two primary factors: (1) your utility service and (2) your power needs. Determining your utility service is as simple as opening up your service inlet box and checking the panel. Typical services can range anywhere from 100 amps up to 400 amps.

Switch ranges
100 amp and 200 amp automatic transfer switches can manage primary (critical) loads for all homes, and can be installed with any incoming utility service (100-200 amp service).100 and 200 amp automatic transfer switches are designed to seamlessly provide power to all circuits in your home. However, depending on your home’s power demand, you may be required to manage (defer) non-critical, high power loads in order to keep the generator at or below full capacity.

What is load management?
Most items in your home can be handled safely by a home generator system from 8,000-20,000 watts. However, certain appliances in your home may require larger amounts of power to start and run when the power goes out. For example, a central air unit or a furnace heater requires a lot of power to start and operate. So much power in fact, that if other items are also on when the power goes out, most traditional standby generators may very well exceed capacity and experience an overload. Computer-controlled Power Management innovations expand capacity while preventing power overload.

What is the difference between a NEMA 1 and NEMA 3R rated transfer switch?
A NEMA 1 rated transfer switch is rated and approved for indoor home installations. NEMA 3R rated transfer switches are rated and approved for both inside and outside the home installations.