What are the grounding requirements for a subpanel?

A subpanel must have its own grounding system, which typically includes a separate ground wire connected to the building's grounding electrode system. The grounding conductor should be sized according to the National Electrical Code (NEC) and must connect to the subpanel's ground bus. Additionally, the neutral and ground must be kept separate in the subpanel to prevent neutral current from flowing on the grounding system. It's essential to ensure that the subpanel is properly bonded to the grounding system to ensure safety and compliance with electrical codes.