How much for a layman to dig his own sewer connection? How much for a layman to run out his gas connection? How much for a layman to install a modern breaker? H

How much for a layman to dig his own sewer connection? How much for a layman to run out his gas connection? How much for a layman to install a modern breaker? How much for a layman to know what code to even follow? Reasoning from first principles is great but building a modern code-compliant house isn't going to be possible for a layperson without guidance every step of the way. Move fast and break stuff isn't going to fly in real construction.