Describes requirements and dimensions of PVC insulated cables, in multicore and multipair construction, with or without screens and optionally incorporating single wire armour. The insulation of instrumentation cables is suitable for operation at voltages up to 300V r.m.s. core to earth and 500V r.m.s. core to core. Instrumentation cables are not for direct connection to low impedance source, e.g. public mains electricity supply.