A transfer switch is required by the NEC for any connection of power to a home. An automatic transfer switch isolates your home from the power lines. This prevents back-feed, which occurs when the power goes back down the utility lines. Backfeed can not only damage the generator but has the potential to cause fires.

Are generator transfer switches safe?

A transfer switch is the key to safe and convenient operation of portable generators for standby power. By isolating those circuits using generator power, a transfer switch eliminates the risk of back-feeding the electrical utility which can cause injury to workers and property damage.

Is backfeeding illegal?

Backfeeding is the tying of a portable generator directly to your homes electrical panel instead of using a transfer switch. It is dangerous. It is often illegal. And it should never be attempted under any circumstance.