Ralph Mowery wrote:

"Tony944" wrote in message
...

.
The other would be if there isn't a empty spot for an additional
double pole breaker.

No breaker will do the job he needs DPDT Manual swtich



You install a breaker to go to the generator. The lockout plate prevents
this breaker from being turned on if the main breaker going to the power
lines is on.

In effect a DPDT switch is created. The handles are just not connected.

Not connected, but "mechanically interlocked" so that both cannot be on
at the same time.

There are many approved interlock kits available, including ones from
the manufacturers of the panels themselves. They work very well and are
very cost effective for generators all the way up to 30KW (125A max
branch circuit breaker size).