4.8.2 Array insulation resistance d

4.8.2 Array insulation resistance detection for inverters for ungrounded and functionally grounded arraysNOTE The requirements in this subclause regarding detection and response to abnormal array insulation resistance to ground are intended to reduce fire or shock hazard due to an inadvertent connection between the array and ground. In a non-isolated inverter, an array ground fault will result in potentially hazardous current flow as soon as the inverter connects to the mains, due to the earthed neutral on the mains, so the inverter must not connect to the mains. In an isolated inverter, if a first ground fault in a floating or functionally grounded array goes undetected, a second ground fault can cause hazardous current to flow. The detection and indication of the first fault is required, but the inverter is allowed to connect and commence operating, because the isolation in the inverter means the earthed neutral on the mains will not provide a return current path for the fault current.