What is a Transfer Switch and How Does it Work?

Atransfer switch is a device that serves two functions: connecting various electricity sources to a single electric load and safely disconnecting these sources from the electric load. The portable backup generator that you use in your home (see Best Home Generator for the Money) has a transfer switch to ensure that it can isolate different electricity generating sources when you don’t need them and provide a smooth transition from non-operational to operational mode whenever required.

How Does the Transfer Switch Work?

The transfer switch contains the main breaker that switches the primary power source to your standby backup generator (learn how to use a generator to power a house). This allows the transfer switch to act as an intermediary between your house’s power source and the devices you want to run. That is why electrical technicians also call the transfer switch an electrical relay.

When the main breaker starts transferring power, it simultaneously stops the generator’s power from back-feeding. Otherwise, the back-feeding would take place through utility power and utility lines.

The transfer switch contains multiple circuits that can distribute power to different appliances in your room. For example, you can assign one of the circuits to power your living room, while another can light up your bedroom or bathroom. However, you need to consider the size of your generator and its wattage to light up multiple appliances in your house.

Why Use a Transfer Switch?

Using a transfer switch is the best way to connect your generator to your house. It isolates your house from its power lines, thus not allowing back-feeding. Back-feeding leads to damaging the generator and even causes fire. In fact, there are many cases where back-feeding led to electrocuting people who touched the generator while it was on or trying to work on the power lines to restore power.

Using extension cords for every appliance to connect with the generator is a time-consuming job. Instead, you can connect your home’s power supply to the generator and let the transfer switch take over whenever you need to power the appliances during an outage.

Types of Transfer Switches

There are three types of transfer switches that you need to know about:

1. Utility-to-generator transfer switches

A transfer switch is responsible for preventing electricity from traveling from your generator to the power grid, thus ensuring that electricians working on the power lines don’t get electrocuted. This is one of the reasons why electric codes make it compulsory to use a transfer switch when you connect a generator to your home’s electric panel.

In addition to residential generators, power generators used in various industries also require transfer switches. Some of them require special features, such as the backup power from the data center should become available instantly right after a power outage.

2. Utility-to-utility transfer switches

This type of transfer switch is useful when the facility has requirements for multiple utility service feeds. The utility-to-utility transfer switch allows you to switch to a different service if its counterpart doesn’t work. For example, many apartment buildings have multiple electrical meters on a single electrical system. Therefore, when one tenant is not present for a significantly long time, the owner can switch the respective meter off to cut down his energy expenses.

Using the utility-to-utility transfer switch in such cases allows every tenant to be responsible for his own electrical consumption. If he fails to switch off the electric supply from the primary power source, the owner can cut the power using the transfer switch.

3. Generator-to-generator transfer switches

You need generator-to-generator transfer switches in locations that require multiple on-site power supplies. This is a necessary piece of equipment that you need in your house if it has a generator and solar panels. The transfer switch will isolate the generator and the solar panels, otherwise, the AC inverter that comes with the solar panels would attempt to back-feed power to the generator, thus causing electrical hazards both to the inverter and the generator.

The generator-to-generator transfer switch, in this case, will allow you to switch between the generator and the solar panels as and when you want and would keep them electrically separated. You can also see these switches in industrial facilities that have multiple on-site gensets.

Final Words

If you are planning to buy a generator, it is a good idea to also look into using a transfer switch to hook it up to your home’s power supply. A transfer switch not only provides convenience during a power outage, but it also offers the safest method to reduce the chance of electrical hazards and accidents. Ensure that you contact a licensed electrician to install the transfer switch if you are not experienced in working with electricity.