[RE-wrenches] GEC for Enphase inverters

[Brian Mehalic]

According to the Enphase website (/support/faqs):

"The Enphase Microinverter manual states that the device is positively
grounded. Don't most PV modules have negative grounds? Is this a problem for
Enphase?

Enphase made the decision to positively ground its microinverters to
minimize corrosion. Because Enphase Microinverters are positively grounded,
they are compatible with both positively and negatively grounded modules."

Now I couldn't actually find that anywhere in any of their installation
manuals...but the instructions for "Grounding the System" does say to "Route
a continuous GEC through each of the Micro-inverters and AC branch circuit
junction box to the NEC approved AC grounding electrode."  Clearly this
conductor will function as both the DC GEC and the EGC, too.

Inspectors in Arizona (some of them anyway) have been allowing the DC GEC to
land on the ground buss in the main service for some time.  I sort of find
the idea of an irreversible bond a little silly (well especially where the
two GECs must come together) - I've worked on a lot of systems using only
ground rods, and the connection to them is often made with the most
reversible of connectors (an acorn), and usually it is excessively
accessible.  And of course the other end of the AC GEC is landed on a bus
too.

Brian

On Tue, Sep 14, 2010 at 11:09 PM, R Ray Walters <ray at solarray.com> wrote:

> It seems to me that William's original question of where does the EGC stop,
> and the GEC begin, all depends on whether the Enphase inverters bond
> negative to ground internally.
> Did we ever get an answer from Enphase?
> If they don't, then I think by definition in article 100, we would only
> have an EGC (no DC GEC, since neither DC conductor is grounded).
> If they do bond neg. to ground, then from the inverter all the way to the
> electrode should be an "unbroken" DC GEC, and stopping at the main service
> ground buss would constitute a prohibited reversible connection. (it seems
> we should at least bond irreversibly to the AC GEC after it leaves the buss,
> or sink another electrode for the DC GEC and the array frame as required by
> 690.47(D))
>
> Please, somebody flog me with some facts and code, so we can put this dying
> horsey to bed.
>
> R. Walters
> ray at solarray.com
> Solar Engineer
>
>
>
>
> On Sep 14, 2010, at 6:31 PM, August Goers wrote:
>
> Hi All -
>
> I would just add that having a good c-tap crimping tool on hand is just
> about as valuable as it gets in the solar business. I remember holding off
> on getting one because of the $200 or $300 price tag but once you have it
> you won't believe you lived without it. The possibilities are almost
> endless, but we use our crimpers to bond our GECs to the other existing GECs
> all the time. Ctaps almost always replace wire nuts when dealing with bare
> copper EGCs. The c-taps typically cost less than $5 a pop and always save
> that much on labor. Most time when we have a multiple string inverter
> installation is makes sense to irreversibly crimp the GECs together and run
> one wire back home.
>
> Greenlee, Panduit, etc make good tools and taps. Let me know if you would
> like part numbers... -August
>
>
>
>
> On Tue, Sep 14, 2010 at 8:41 AM, Bill Brooks <billbrooks7 at yahoo.com>wrote:
>
>>  T
>>
>
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-- 
========================
Brian Mehalic
NABCEP Certified Solar PV Installer™
PV Online Coordinator
Solar Energy International
Carbondale, CO 81623
http://www.solarenergy.org
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