[RE-wrenches] DC positive and negative in same conduit, other inspection issues

[Dave Click]

All,

Couldn't find this anywhere in the archives; sorry if it's a repeat. I 
just went out to inspect a ground-mount system that had 3 source 
circuits feeding a metal DC combiner/disconnect. Wiring was free air 
until it got near the disconnect, then the positive wires entered an 
open 3' section of FNMC (no strain relief or box at the other end of the 
FNMC). The negative wires ran through a *separate* 3' section of FNMC. 
The array had N-S-run support rails, and along the top of each rail was 
run a #6 bare continuous through Wiley lugs that ran to a ground rod on 
the west end. This #6 bare used split bolts to connect #6 bare taps to 
the disconnect switches, with the #6 bare entering a separate knockout 
from the positive and negative wiring conduits, with strain relief 
provided by... a romex cable clamp. This was then repeated on the rest 
of the 75kW array.

So I found the following corrections:

1. Running the positive and negative wires through separate conduit 
violates 300.3, and could cause eddy currents in the combiner/disc boxes.
2. Running the equipment ground separately from the +/- wiring is also 
not code compliant
3. Using romex cable clamps for something other than Romex is also less 
than correct, and I imagine that has some effect on the UL listing or 
warranty of the NEMA 3R box (at least the clamp is in a bottom knockout, 
but still)
4. When entering the open conduit with USE-2 home runs, you need to have 
some kind of strain relief; I usually recommend liquid-tight cord grips, 
against the wishes of 98% of the installers that I speak with.

For the grounding electrode wiring, it seems that it's fine to me since 
they ran the continuous #6 to each rail and then to the rod, qualifying 
as the 690.47(D) supplemental electrode. But the split bolts tapping 
that GEC to "ground the disconnect," these are required to be 
irreversible connections to the ground bus in that disconnect, right?

Did I miss anything? Thanks for reading this far and for the backup.

Thanks,
DKC