# Sharing a ground wire - Multiple circuits in common conduit



## Carultch (May 14, 2013)

The application is for identical DC Feeder circuits of a solar array, from a combiner containing three combination zones, each feeding a separate inverter.

There are no overcurrent devices required anywhere, because each circuit is fed by two DC strings from the field. 690.9 exception.

#10 is the default ground size per 250.122. I'd make it #8 if I were doing one common ground wire. It all connects to the common metal racking system.

So the question is, can it be 1 ground for 3 inverters, distributed to each inverter via a ground bar? Or should it be a separate ground for each inverter DC circuit?


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## Yomanyouahippie (Aug 22, 2013)

I have always seen a ground bar in troughs for multiple inverters. One #6 per pipe one side hits the bushing and bar then the inverter, the other side hits bushing and then racking


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## Dennis Alwon (May 9, 2009)

Carultch said:


> The application is for identical DC Feeder circuits of a solar array, from a combiner containing three combination zones, each feeding a separate inverter.
> 
> There are no overcurrent devices required anywhere, because each circuit is fed by two DC strings from the field. 690.9 exception.
> 
> ...


I dion't believe you need to upsize the equipment grounding conductor. If 250.122 requires a #10 then that is all you need even with multiple units.

The equipment grounding conductor is there for ground fault and short circuit protection. Art. 690.45 states to size the equipment grounding conductor based on the Table when no overcurrent protective device is employed

This is from 2014



> 690.45 Size of Equipment Grounding Conductors.
> Equipment grounding conductors for PV source and PV
> output circuits shall be sized in accordance with 250.122.
> Where no overcurrent protective device is used in the circuit,
> ...





> 690.46 Array Equipment Grounding Conductors. For
> PV modules, equipment grounding conductors smaller than
> 6 AWG shall comply with 250.120(C).
> Where installed in raceways, equipment grounding conductors
> ...


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