A backfed generator breaker is a breaker that feeds power from a generator into your electrical panel, rather than drawing power out to a circuit. It is one way to connect a generator to a home, and it is used with a mechanical interlock that prevents the generator and the utility from powering the panel at the same time. Understanding how a backfed generator breaker works, and the safeguards it requires, explains why this connection must be done professionally.

Here is what a backfed generator breaker is.

How it works

Normally, a breaker in your panel feeds power out to a circuit. A backfed generator breaker reverses this, bringing power from the generator into the panel’s bus, where it can supply the home’s circuits. The generator connects to this breaker, and when the generator runs, its power feeds into the panel through it.

This is a common method for connecting a portable generator to power a home’s circuits through the main panel.

The interlock is essential

A backfed generator breaker is used with a mechanical interlock, which is the key safety component. An interlock is a device that physically prevents the main breaker and the generator breaker from being switched on at the same time. This ensures the panel is powered by either the utility or the generator, never both.

Why does this matter? If the generator could feed the panel while the panel was still connected to the utility, generator power could flow back onto the utility lines, a dangerous condition called backfeed. Backfeed can endanger utility workers and damage equipment. The interlock prevents this by forcing you to switch off the main before switching on the generator breaker.

The hold-down requirement

Because a backfed breaker has power coming into it from the generator, code requires it to be secured in place with a fastener or hold-down clip so it cannot be pulled loose from the bus while energized. This hold-down is an important safety detail that a licensed electrician installs as part of the connection.

Backfed breaker and interlock versus a transfer switch

A backfed generator breaker with an interlock is one way to connect a generator; a transfer switch is another. Both accomplish the same essential goal of keeping the generator and utility isolated to prevent backfeed. The interlock method uses the existing panel with a backfed breaker and interlock kit, while a transfer switch is a separate device. An electrician can recommend the right approach for your generator and panel.

Why professional installation is required

A backfed generator breaker connects a generator to your panel and relies on the interlock and hold-down to prevent dangerous backfeed. Installing it correctly, with the proper interlock, hold-down, and code compliance, requires a licensed electrician and the permit a generator connection needs. Improvised generator connections without these safeguards are extremely dangerous.

A backfed generator breaker feeds generator power into your panel and is used with a mechanical interlock that prevents the generator and utility from powering the panel at the same time, avoiding dangerous backfeed. It also requires a hold-down to secure the breaker. It is one method of connecting a generator, alongside a transfer switch, and because of the safety requirements, it must be installed by a licensed electrician.

Stella Electric installs safe generator connections, including interlock and transfer switch setups, for homeowners across the Baltimore area and throughout Maryland, with flat-rate pricing and no overtime charges. If you are connecting a generator, we will do it safely. Financing is available on qualifying projects.