This residential electrical circuit picture shows that the service entrance is the cable running from the meter to the breaker box. The electric utility company will put in the transformer, underground line and the meter. In most cases, it is the owners responsibility to run the cable from the meter to the breaker box.
You will need to be sure what size of cables need to be used. Your local Electric Wholesale outlet will know this, but your inspector will also know. It’s most likely something like 1/0 gauge cables. It is Aluminum-clad cable and it is almost as big around as a garden hose.
You will need three cables. Two will be 120-volt lines that connect to each hot bus bar and one will be a neutral line that goes directly to the neutral bus bar in the breaker box.
All the white neutral wires from each circuit will end up in the breaker box and will need to be attached to the neutral bus bar.
Each hot wire will be connected to the breaker of the right voltage and amperage.
The breakers just pop into place.