Insulation is checked by measuring either leakage current or insulation resistance, following the normative methods in Appendix E, with results compared against the leakage current limits in Table 2.1 or the minimum insulation resistance values in Table 2.2 for the class of equipment. The leakage current method is preferred for equipment with single-phase motors or where electronic components such as LEDs make an insulation resistance test fail, and it must be used where the item has to be energised to close a switching device. Portable RCDs with a functional earth have their own lower resistance limit or may be leakage-tested instead. Limit values are those in the current edition's tables.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.