517.a- Yes, if the main circuit breaker rated 1200 amps is GFP protected at the service, then all the breakers that feed subpanels downstream must also be GFP protected.517.b- Yes, if you feed from one subpanel downstream to another subpanel (e.g., from an 800-amp subpanel to a 400-amp subpanel), the 400-amp breaker must also be GFP protected.

Explanation:

The purpose of ground fault protection (GFP) is to prevent dangerous electrical surges and shock hazards by quickly interrupting the circuit when a ground fault occurs. Section 517 of the National Electrical Code (NEC) requires GFP protection for certain electrical systems, including service equipment rated over 1000 amps.By requiring that all breakers feeding downstream subpanels be GFP protected, the NEC ensures that the GFP protection provided at the main service equipment is maintained throughout the entire electrical system. This helps to protect personnel and equipment from electrical hazards, regardless of the location of the subpanels or downstream circuits.The requirement for GFP protection continues in a series, meaning that if a subpanel is fed from a GFP-protected panel, any subpanels fed from that subpanel must also be GFP protected. This ensures that the GFP protection is maintained throughout the entire electrical distribution system. Flag for review