How to plug the portable generator into a “wall outlet”

I will join longneck, you need to give to give this one to a pro.

If you do not understand about back-feeding a circuit, already, it is too easy to kill someone. I say this without exaggeration.

The biggest problem with running a generator with a transfer switch is that you have to wire it into your main panel.

For basic protection of life, (as well as the law,) it must NOT be possible to have your generator and the power to your house on the same wire, at the same time.

This is not a case of, just for a few seconds, or I would not do that, or I will triple check a written list.

It must not be possible under mechanically, electrically, on with quantum physics.

The reason is that if you put power on the 'dead' wires to your house, it is possible to kill someone a mile away, or more.

Emergency workers expect down lines to be dead. Yes, they do check first, but that does not mean that the situation can not change while they are working on them.

Transformers work backwards, low voltage at your generator (240) quickly becomes high voltage (thousands).

And sometimes people, and pets, or cars, just do not even see a fallen power line.

This is a case of some money to a pro vs life.

You need a generator inlet that feeds a single outlet.(you seem to know what an inlet is, but it doesn’t need to feed the breaker box, it could just feed a single outlet.) This new outlet should be placed next to your current sump pump outlet, and properly labeled to avoid future confusion. (Assume here I’m talking about a future homeowner or tradesman— you won’t be confused but others might be in 10-20 years.) This new outlet would be dead when not fed by the generator.

Do NOT run your generator in the garage, it must be outdoors! Generators emit Carbon Monoxide which is odorless and extremely lethal.

(Note: the linked example is weatherproof, non-weather proof models are made for standard knockout sizes the are found on Hoffman-style enclosures, which are typically larger than needed for this project. Since the easiest to install are all weatherproof there is a message there—these should be indoors or in the garage.)