How do you run a new breaker box in a detached garage from the existing breaker box in the house?

Answer 1

for USA, Canada and countries running a 60 Hz power supply service.This is too involved to answer in a few short sentences. Get an electrician to do the work safely or a really good book on the subject.

<><><>

One thing that most home owners don't understand, although the NEC is quite clear on this, is that if the sub-panel is in a detached building, it gets its own ground. You don't run a ground wire from the main panel to the sub-panel. Rather, you run only the neutral and two hots, and bond the neutral to the ground within the sub-panel, then ground it to an 8 foot long rod pounded into the ground, or other appropriate ground.

This is all quite different from the sub-panel being in the same building as the main panel. In that case, you run a separate ground wire, and don't bond the neutral and the ground at the sub-panel.

<><><>

As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.