[RE-wrenches] GEC tap

[Corey Shalanski]

Kris,

As far as I know, taps to GECs need not be irreversible. I believe you
might be thinking of the NEC 250.64(C) requirement for GECs to be installed
"in one continuous length" or otherwise be spliced together via one of
several options, with one option being to use irreversible compression-type
connectors—but I'm pretty sure that refers to *individual* GECs (as in,
*each* GEC must either be run continuous or can be pieced together via
irreversible means).

It sounds like your scenario is a supply-side connection, which introduces
an additional service equipment enclosure in the form of the PV system
disconnect (additional to any existing service equipment) and would
therefore be covered by NEC 250.64(D). One option, described in (D)(2),
would be to run a new GEC from the PV system disconnect directly to the
(existing) grounding electrode system. The other option*, described in
(D)(1), is to run a GEC "tap" from the PV system disconnect to a "common"
GEC. In cases where there is only a single existing service equipment
enclosure - and therefore only a single existing GEC - my interpretation is
that the existing GEC can serve as the common GEC (essentially doing double
duty as a "common/tap" GEC, if it helps to think of it that way) and you
can therefore connect the new GEC tap directly to it. Notably, this method
allows for the use of "connectors listed as grounding and bonding
equipment"—we commonly use split bolts for the purpose.
*There is also a third option [(D)(3)], but, in my experience, it is
uncommon to have wireways on the supply side of service disconnects.

So, I would suggest there is no need to use compression connectors - but
you can certainly do so as an 'above-Code' measure.

Corey Shalanski
Cherry Street Energy
Atlanta, GA


On Wed, Feb 19, 2025 at 8:18 AM Kristopher Schmid via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hi All,
>
> What are you all using for an "irreversible" tap to an existing GEC?  I
> have been looking at compression CTAPs.  Do they require a special crimper
> die?
>
> Thanks,
> Kris
>
>
> Shine On!
>
> Kris Schmid
> Legacy Solar, LLC
> 137 West 1st Avenue
> Luck, WI 54853
> www.legacysolar.com
> 715-653-4295
> NABCEP Certified PV Installation Professional
> Licensed Wisconsin Master Electrician
> BSEE
>
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