Ungrounded PV array

In an ungrounded or floating PV array, neither DC conductor is deliberately connected to ground. The exposed metal parts are still earthed, including module frames, racking, enclosures, junction boxes and conduit. Some three-phase string inverters are built for this setup. The Solectria PVI 25TL-480-R may only be installed with floating or ungrounded arrays, and CPS SCH-series inverters list an ungrounded array as their DC input type. An inverter that runs an ungrounded array still needs equipment grounding, including a DC equipment grounding conductor. The grounding busbars are bonded together through the inverter chassis. Touching the frame of an ungrounded module or array can cause a fatal electric shock. Bond and ground all frames and conductive surfaces so they form one continuous path, following local rules. Floating systems need specially listed inverters that can detect array faults. Both ungrounded DC conductors need wiring protection, disconnecting means, overcurrent protection and ground-fault protection. Class II modules, cables and connectors together with an inverter that has an isolation transformer let the array frame stay floating. Faulty equipment or damaged insulation can still cause accidental earth leakage. Insulation resistance (meg) testing uses separate procedures for source circuits and combiner boxes in an ungrounded array.

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• sentence 7: support check: partial - Passages list separate cases for ungrounded source circuits and combiner boxes with a procedure for each, but do not explicitly say the procedures differ between those two. -->