Outlets, switches & breakers

Do you need a transfer switch for a backup generator

A transfer switch safely connects a generator to your home's circuits and prevents backfeeding power into utility lines, which is both a safety requirement and often a legal one.

Difficulty
Professional only
Time
2–4 hours to install
DIY cost
$0
Pro cost
$500–$2,000

Symptoms

  • Currently running extension cords from a portable generator into the house
  • Considering a generator for power outages
  • Unsure how a generator should safely connect to household circuits

Likely causes

  • CommonNo transfer switch currently installedMany portable generator owners start out running extension cords rather than installing proper switching equipment.
  • PossibleAttempting to backfeed the panel through a dryer outlet or similar shortcutThis is a well-known and dangerous practice that can energize utility lines and endanger utility workers.
  • PossibleAn undersized or incorrectly matched transfer switch for the generatorA transfer switch not sized to the generator's output can limit which circuits can safely be powered.

What to do

  1. Stop using any method that plugs a generator into a household outlet to power the house, including through a dryer outlet.
  2. Decide which circuits you actually need powered during an outage, like the fridge, some lights, and a sump pump.
  3. Have an electrician install a manual or automatic transfer switch sized for your generator's output.
  4. For a portable generator, ask about an inlet box that lets you plug in safely to the transfer switch from outside.
  5. For a standby generator, confirm the transfer switch and generator are sized appropriately together.
  6. Test the system periodically, ideally with the electrician's guidance the first time.
  7. Keep the generator itself outdoors and away from windows or doors due to carbon monoxide risk.

Tools and parts

Manual transfer switchSearch: “manual generator transfer switch kit”

When to call a pro

Have a licensed electrician install a transfer switch matched to your generator; this is required for safe, legal generator use with your home's wiring.

Safety

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.