Why all the talk about three way switches for making a transfer switch? Why can't I use a double poll double throw center off switch. Normal power on one side and generator on the other. In this application neither source ( generator or normal house side) will ever back feed. The generator is fused on both 110 feeds.

As long as the DPDT Center off switch is rated to handle the load, and is clearly labeled, and is at the branch circuit level, I see no problem.

If this will be part of the service, it needs to be SE rated.