How do generator transfer switches work?

A generator transfer switch is an ingenious device. It works by transferring your home’s internal power circuit from depending on the main electrical grid to depending on your home’s generator instead.

Your home’s circuit becomes the only path that will connect to any outside power through a transfer switch. The switch can then be used to close the circuit with the electrical grid or with your generator.

There are a few factors that your transfer switch depends on. All houses are wired differently and depending on this, and the amount of power your generator gives, you may need a whole house transfer switch for your generator for maximum power. On the other hand, you may just require a partial transfer switch.

If all of your appliances are running on a single circuit breaker, these can be moved as an entire unit onto a transfer switch. If your home has a separate breaker for heating or a well pump, your appliances will need a secondary transfer switch.

The use of a generator transfer switch depends on its type. These can be either manual or automatic switches.

Manual transfer switches have to be manually opened to access a circuit for you to move your home’s power from the electrical grid to your generator and then back. This is a very easy process but means you will have a few minutes without power in the case of a blackout. 

Automatic transfer switches automatically detect when your power goes out. It proceeds to switch your home straight onto your generator’s power supply. This is only helpful if your generator is capable of turning on automatically when the power goes off. Nonetheless, most permanent home generators are built to do this.

Why do you need a generator transfer switch?

Whenever you use a generator in your home, a transfer switch is required. The National Electric Code set forth a law to make it a mandatory device when running a permanently installed generator. Failing to do so can void your insurance and it is seen as a code violation.

If you run appliances such as sump pumps, a furnace, a well pump, or a hard-wired refrigerator, you will definitely need a transfer switch. If you use smaller electrical devices such as smartphones or laptops, transfer switches aren’t as crucial in a power outage.

It’s important to note that if you use a generator for recreational use such as fishing or camping, transfer switch is not mandatory.

The benefits of using a transfer switch

If a generator is run directly, you can’t decide which appliance will run in the future. If the power goes out but you need the lights on, the generator alone can’t send power to one source.

A transfer switch will kick in and run power directly to the appliances you need most during a power outage.

Another benefit is how a transfer switch can easily send power from one room into another via a route. This is particularly helpful if your generator cannot run many appliances at once.

Without a transfer switch, you will have to lay down power cords throughout the whole house, which isn’t really an option. A transfer switch ultimately eliminates any need for extension cords as it is connected to the house’s mains supply circuit directly.

Transfer switches are also the safest way of connecting a generator to your home. If you were to use extension cords, this could cause back feed. This is when power from your generator flows back into the main grid, energizing transmission lines. This can cause fatal injuries to electricians who may be working on a nearby transmission line.

Power that runs from the main grid and the generator can also cause a short circuit when flowing together through your home’s electrical appliances resulting in possible electrocution.

Transfer switches prevent this problem. It does this by disconnecting the power supply from the main grid and instead connects the power from the generator to your home.

It works in a similar way when the grid’s power supply comes back on. The transfer switch will then disconnect the generator avoiding any chance of a short circuit.

A generator transfer switch’s size

This depends on the power your generator can produce. A transfer switch should be rated for at least as much wattage as the maximum power your generator can produce. (Slightly more to be on the safe side)

Most homes require less than 10 circuits on the transfer switch. This all depends on how the electrical appliances within your home are arranged on your circuit breaker.

In Summary

A generator transfer switch is an essential device that is legally required. These switches will ensure your generator and electrical grid won’t feedback into each other resulting in a possible catastrophe.

As long as the generator transfer switch is rated for at least the same amount of wattage as your generator, and a little more, the transfer switch should keep your home running smoothly and efficiently when the power goes out next.