· Scared Electrician
For a 30a service to an out building you will need 4-10ga wires. H-H-N-G If no more than 6 breakers you will not need a disconnect. You will have to install a ground rod at the out building. You will have to keep all neutrals and grounds separate at the out building. Sorry it will be difficult to post code sections as this is a summary of many articles. Romex cannot be used outside nor underground, so this will have to be UF cable @24" deep or conduit and THWN @ 18".