AC to DC Bonding & GEC/EGC sizing

[bbehringer]

I have two issues regarding AC to DC bonding and EGC/GEC wire sizing.

Design: 2 Roof Mounted PV Arrays (Array 1 4.5kw, Array 2 3.0kw), fed to seperate inverters (Inv 1 20a, Inv 2 12a), from the inverters to a 100a subpanel, subpanel to 60a Non-Fused AC Disconnect then backfed into 40a-2p breaker at the main 200a service panel (120/240v/1 ph, 3w).

Bonding AC to DC, I am running my ground wire, jumped from panel to panel undert the array (bare #8), from the array off the roof to each inverter in seperate EMT with seperate bare #8 G.C. From each inverter the EGC and GEC is run through the subpanel, through the ac disco, into the main SP and bonded to the existing ufer ground. Is this correct bonding of AC to DC as you see it?

Regarding Sizing Combined GEC/EGC. Currently I am running #8 from the Arrays down to the main service panel. If the GEC/EGC are combined per 690.47 do I need to increase my ground wire to #6?

 

[Zee]

#8 is fine for combined egc/gec.

You need continuous, unbroken GEC , not cut or spliced.

Bonding bushings everywhere on EMT if GEC inside.

In my opinion CODE allows you to end GEC at sub-p, if it is where inv.s feed.
Others differ. See yesterday's (?) thread..

If you do actually run combined egc/gec to MSP, then usually we land that on the busbar.
If not combined egc/gec and just GEC is run to MSP, then you cannot land on busbar, instead you must:
1. either irreversible splice to (E) GEC
2. or if you run GEC to UFER electrode itself, then clamp OK.