Potential sources of electric shock must be identified before work begins, including voltage between actives and between active and neutral; between actives and earth, metalwork, damp or conductive surfaces or nearby people; across open switch contacts; on undischarged capacitors such as EMI filters; on disconnected conductors, especially neutrals; from static; from earth potential rise in MEN systems where the return path to the supply has high resistance; induced voltage; transformer and current transformer secondaries; between different earthing systems; wrong connections; faulty equipment making frames live; other sources of supply such as illegal connections, UPS units, motor generator sets, inverters, solar arrays, batteries and wind turbines; lightning; breaks in a metallic incoming water supply; unexpected switching by float switches, thermostats, timers or photocells; drilling or fixing into structures hiding conductors; and electric welders.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.