The Size of a Residential Transfer Switch

Size

• The size of the transfer switch you use for your electrical generator depends on various factors such as the number of appliances you intend to operate on your generator's power. Transfer switch sizes are measured in amps and generally range from 50 to 200 amps. Large transfer switches are typically needed for whole home operation. Generally, this requires a 100 to 200 amp switch, whereas limited residential operations can be carried out with a 50 to 100 amp switch.

Calculation

• Calculating your electrical needs is integral to choosing the right size transfer switch. The square footage of your home should be taken into account for your lighting needs. Additionally, you have to determine the specific appliances, entertainment items, heating and cooling and cleaning needs you utilize. Two primary considerations to make when choosing your generator is the number of starting amps you'll need to get your electric-using devices going. You also need to know the running watts that it takes to keep your devices going.

Types

• The size of the transfer switch is only one consideration when connecting a generator to your home's electrical supply. Generally speaking, you have three primary options at your disposal. If you think your generator may only need to be used a limited number of times throughout the year, use a manual switch. Automatic switches kick in on their own in the event of a power outage, but may only be needed in cases where power outages are frequent. Some switches are built as combination switches, allowing you to choose between automatic and manual transfer.

Legal Considerations

• Before you think about bypassing a transfer switch for your generator, note that it is illegal to do so if you plan on hooking up your home's electrical system to the generator itself. It is one thing to plug in one or two appliances, a light and a heater into a generator for a short period of time. It is another to put your generator on the same circuit as the rest of your home. This is where backfeeding becomes a possibility. If your power comes back on, the voltage in your lines can feed back into electrical supply lines and this can be dangerous for you, your neighbors and utility workers who are unaware of the excess voltage.