240 v sub box/panel 160 feet from main, what size and kind of wire or romex/ conduit is aproved?

Allen,

Welcome to the forum.

We need a lot more information before we can help you.

What is the NEC level being used in your area?

Have you applied for and received your electrical permit? You also need an inspection. Your insurance company will need proof that the work was completed to "Code".

The NEC only allows one point of service for a single family residential dwelling so you would need to use a sub-panel.

Will the sub-panel be in the same building as the main service panel or will it be in a remote building?

What is the amperage that you need at the sub-panel? That's what will set the breaker and cable size.

Will you be using copper or aluminum conductors? That also will help set the size of the conductors.

Are you going to use a "MLO" type panel as a sub-panel, in which case you would need a main disconnect switch in front of the sub-panel (so you can kill all the power to the sub-panel in an emergency). Or you could use a MLO sub-panel with no more than six breakers to kill the power to the panel. You can also use a "Main Breaker" type panel so you can kill the panel quickly.

Personally, I prefer the "Main disconnect switch" configuration.

Knowing whether the sub-panel is in the same building or not tells us how to set up the grounding system.

Whether the sub-panel will be in a remote or the same building you must use a four wire cable (Black, Red, White, Bare or Green ground) from the main service panel to the sub-panel.