Under both normal and single fault conditions, accessible parts and applied parts stay within the 8.4 limits on voltage, current and energy. Normal condition includes, all at once, the presence on any signal input or output part of any voltage from other equipment the accompanying documents permit (or the maximum mains voltage where they impose no restriction), transposition of the supply connections of plug-connected equipment, short circuit of any insulation, creepage or clearance that does not itself meet 8.8 or 8.9, and any earth connection that fails 8.6, functional earths included, being open-circuited. Single fault conditions include: a short across one insulation, creepage or clearance that forms one means of protection; a short or open circuit of a component (except a high-integrity one) wired in parallel with insulation or a distance, unless a short is shown not to be a way it can fail; a break in one protective earth conductor or one internal earth connection (the earth of permanently installed equipment excepted); a break in one supply conductor (the neutral of polyphase or permanently installed equipment excepted); a break in a power conductor joining parts housed in separate enclosures, where the risk analysis shows limits could be exceeded; a component moving unintentionally when the risk management process does not show it is firmly mounted; and conductors and connectors coming loose by accident where their breaking free could be hazardous; accessible parts are determined under 5.9 and leakage currents measured under 8.7.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.