Does anyone know the underground depth required by NEC for branch line? It is about a 100' run to a pole building 100 amp service. 220v...? thanks
You would need to provide the following info: voltage, what is it being buried under, wiring method etc.
Your burial depth does depend on if you're using conduit, or direct burial cable. The answer comes from Table 300-5. Assuming we are NOT going under a street, roadway, driveway but merely across a yard. Rigid conduit = 6", direct bury cable = 24", UF = 18". If your conditions are different, let us know.