Protection against exposed conductive parts becoming live under fault is by automatic disconnection of supply, Class II or equivalent insulation, electrical separation, or limiting fault current below shock level. Automatic disconnection needs bonding of exposed conductive parts to protective earth and a protective device that cuts supply wherever a fault could raise touch voltage above 50 V (a.c.; 120 V for ripple-free d.c.), with earth fault-loop impedance low enough to disconnect in time: 0.4 s for final subcircuits supplying socket-outlets up to 63 A or hand-held or portable equipment, and 5 s for other circuits at 230/400 V.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.