[RE-wrenches] bare tinned solid copper

[Phil Schneider]

Wrenches,

We are working through submittal steps for a 75 kW ground mounted array.
 The array is split into 8 subarrays.  There is a combiner or junction box
at each subarray, with a ground rod spec'd at each subarray, underneath the
"box station", with a bare stranded #6 from an equipment grounding bus to
the rod, and equipment grounding conductors through conduit between a ground
bus in each box.  15A fuses in combiners, and 100A fuses at inverter.

The engineer we're working with to stamp the plans wants to see bare,
tinned, solid copper anywhere this equipment ground is in the elements, and
wants to see #2 (!) bare, tinned, solid copper cadwelded and direct-buried
between all 8 rods and back to the existing AC grounding electrode system.
 He says this is the standard (from telecom, I'm afraid) to ensure that all
the rods are at the same potential.  No Code reference, and I don't see
anything in article 250 along these lines.  Hard to convince him that #6,
untinned, across the board is adequate.

In the end, we'll probably go ahead and do it because it is relatively low
cost and we want a good relationship here, but I'm wondering if anybody else
out there is using bare tinned copper in this type of application, and I'd
like more info on this to make a better argument next time.

Phil

Phil Schneider
Creative Energies
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