[RE-wrenches] EGC for LFP Battery Circuits

[Jason Szumlanski]

For batteries like the Midnite PowerFlo16 or EG4 Wallmount using a NEC
Chapter 3 wiring method, what do you do in regards to running an EGC with
the DC circuit conductors in a raceway? Midnite, for example, supplies a
#10 EGC to bond the case of the battery, but this is not suitable for a
circuit with an ampacity of 210A per NEC Table 250.122. It's not addressed
in manuals from these manufacturers.

It would be easy enough to run a #4 copper EGC with the 2/0 battery cables,
but where would you terminate it at the battery end? The case ground screws
are far too small. I suppose you could use a grounding bushing if the
raceway is not itself qualified as the EGC. In cases where you have a
conduit box like EG4 or if you set a Midnite AIO on a wiring trough, they
supply plastic bushings to use, so there is no solid electrical continuity
between the inverter and wiring trough, yet you seemingly need to run up to
a #4 EGC through the opening with the battery cables. Where would that
terminate in the trough or on the battery?

I haven't had any issues with AHJs by just running a #10 with the circuit
conductors and making sure all metallic parts are bonded, but something
doesn't seem right about all of this, and I want to be prepared if called
out by an inspector.

Jason Szumlanski
Florida Solar Design Group
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