Hi... I have a regular house with a new 200 amp service, 220.. 30 amp service going to the garage... I have a 5500 watt generator... if I lose power at the house can I back fed the 200 amp box with the wire coming to the garage? Back fed into the 220 30 amp breaker from the garage , as long as I turn off the 200 amp main... I know that I can only run up to 30 amps with my generator but that's OK... I know what things to turn off and what things I can run... I just don't know if back fedding into a breaker works... I m trying to avoid running 10 extensions cords... thanks...

Do an advanced search in the Electrical Forum for Transfer Switch, I found a couple of previous posts to get you started:

https://www.askmehelpdesk.com/electrical-lighting/generator-help-48227.html?highlight=transfer+switch

https://www.askmehelpdesk.com/electrical-lighting/service-panel-upgrade-45129.html?highlight=transfer+switch

I know Labman has done extensive research on finding an inexpensive method of connecting a generator properly to a service. Try to find his posts on the interlocking plate he has found.

What you are proposing is illegal and dangerous. There are several methods available, a manual transfer switch, automatic transfer switch, a prepackage manual system that only does a few circuits, and an interlock plate.

As tkrussel said, do a search. Be sure it include interlock plate as a search term. If you can find one to fit your box, they are the cheap way out. Back feeding works, but the utilities require a positive disconnect so your generator can never be connected to their lines. Otherwise, if you don't throw the main breaker, you back feed right out to the pole, through its transformer and every thing is hot clear back to the outage.

If you manage well, 30 amps can do quite a bit. I am still looking.