A transfer switch is an electrical device that switches a load between two sources. It allows you
to safely connect a generator to your household wiring and prevents the utility power and generator
power from powering your household circuits at the same time thus protecting utility repairmen from
power being backfed as well as protecting your home and generator from damage. The transfer switch
is an essential piece of safety equipment as it is required in all 50 states by the National Electrical
Code. The manual transfer switch and the automatic transfer switch are the two main transfer switch
options to choose from.
With a manual transfer switch, when the power goes out, and everything is dark, you will need
to grab your flashlight and go manually start your generator engine, allow it to come up to speed and
stabilize and then connect it to the transfer switch. Then you will need to throw the lever on the
transfer switch, so your home or business receives power from the generator. Of course, when the
power comes back on, you will also need to manually switch the power back to the utility company and
turn off the generator.
On the other hand, an automatic transfer switch works with no human intervention. The
transfer switch continuously monitors electric utility power. It senses when the power goes out and
triggers a start command to the generator. The transfer switch connects your home or business to the
generator. When the utility power is restored, the transfer switch disconnects the power supply from
the generator; and the generator is automatically shut down after the cool down period.
So which transfer switch should you choose? The manual transfer switch is smaller in size,
faster to fabricate and easier to install which makes it easier on your budget. It is also easier to
maintain than an automatic transfer switch. However, an automatic transfer switch may be needed for
businesses such as hospitals or data centers where there would be harmful consequences if the
electricity is out for more than a few seconds. The extra investment also may be worth it to you simply
for the convenience of everything running automatically.
It can be confusing and overwhelming to decide which transfer switch is right for you as well as
properly sizing the transfer switch to match the power capacity of your backup generator. A qualified
electrician can help you explore your options, provide the professional installation you need to
confidently meet the National Electrical Code requirements, and teach you how to use a manual
transfer switch or set up an automatic transfer switch.