FWIW, remember also that if there is a Neutral connection on the AC side
that this line is grounded (usually) so
there is also that ground connection.
boB
On 11/5/2014 9:55 AM, Rebekah Hren wrote:
Hi Dana,
If you bond the the ac and dc grounding systems using the optional
method outlined in 690.47(C)(3), then the AC EGC and the DC GEC can be
the same conductor (regardless of TL or not). And this section of the
Code specifically allows the DC GEC to be sized per 250.122 for
_ungrounded_ systems (and not larger than the ungrounded conductors).
So in some ways this is an end run around the GEC question.
However, if the inverter manual says to follow 250.166 sizing
requirements, then I'd think 110.3(B) is going to take precedence for
this installation and you don't have much choice except to have a
minimum 8AWG DC GEC conductor and installed per 250.64 - but it could
serve the purpose of the AC EGC too.
Cheers,
Rebekah
On Wed, Nov 5, 2014 at 12:39 PM, Dana Brandt <[email protected]
<mailto:[email protected]>> wrote:
Thanks for the reply and article, August. John Wiles's article
makes a clear statement that the GEC is not required for TL
inverters. I wish the code would say it that clearly! I think I'm
going to have a tough time convincing inspectors the GEC isn't
required with such unclear language in the code. We'll see....
Thanks again!
Dana
Dana Brandt
Ecotech Energy Systems, LLC
www.ecotechenergy.com <http://www.ecotechenergy.com>
[email protected] <mailto:[email protected]>
360.318.7646
On Mon, Nov 3, 2014 at 12:45 PM, August Goers <[email protected]
<mailto:[email protected]>> wrote:
Hi Dana,
This is still a confusing issue, I agree. This article helps a
bit:
http://www.nmsu.edu/~tdi/pdf-resources/IAEI%20Mar_Apr%202012.pdf
<http://www.nmsu.edu/%7Etdi/pdf-resources/IAEI%20Mar_Apr%202012.pdf>
If you look in a SMA TL inverter installation manual, for
example, they only mention equipment grounds -- there is no
reference to a GEC that I can find. The 2014 code doesn't seem
to have clear wording on not requiring a GEC to me but
Rebekah's recap below is spot on. Luckily it is widely
accepted in our neck of the woods that TL inverters don't need
GECs.
I'm not familiar with the Solectria TL product. It sounds like
it will be best to call them if you need to install one of
their inverters.
Best,
August
*From:*RE-wrenches
[mailto:[email protected]
<mailto:[email protected]>] *On Behalf
Of *Dana Brandt
*Sent:* Monday, November 03, 2014 12:06 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Code reference request
I think I'm a bit confused on this point. I can't seem to find
the code that specifically exempts the GEC requirement for
inverters of ungrounded PV systems. The only exception I can
find is only for AC PV modules (2014 NEC 690.47 (C) ).
I just looked in the installation manual for Solectria's new
TL inverters and found this:
"Per NEC 690.47, a GEC must be installed, and the Grounding
Electrode Terminal (GET) conductor must be sized in accordance
with NEC article 250.166."
What am I missing?
Thanks,
Dana
Dana Brandt
Ecotech Energy Systems, LLC
www.ecotechenergy.com <http://www.ecotechenergy.com>
[email protected] <mailto:[email protected]>
360.318.7646 <tel:360.318.7646>
On Tue, Oct 28, 2014 at 11:30 AM, Rebekah Hren
<[email protected]
<mailto:[email protected]>> wrote:
If you are on 2014:
690.47(B)
An ac equipment grounding system shall be permitted
to be used for equipment grounding of inverters and other
equipment *and for the ground-fault detection reference for *
*ungrounded PV systems.*
and 690.47(C)(3)
*For ungrounded systems, this conductor shall be sized in
accordance with 250.122 *and shall
not be required to be larger than the largest ungrounded
phase conductor.
On Tue, Oct 28, 2014 at 2:22 PM, Gary Willett
<[email protected]
<mailto:[email protected]>> wrote:
Kirk:
A DC grounding electrode conductor (GEC) is not required for
inverters that do NOT have a ground reference for the PV+ and
PV- conductor(s) from the PV array.
A GEC is not required if the string inverter is one of the new
TL (transformerless) types. Also, this applies to
micro-inverters such as the new Enphase M250 and later
versions of the M215.
Where this applies, only a properly sized equipment grounding
conductor (EGC) is required.
The EGC is sized according to [NEC 690.45] and can be a
minimum of #14AWG when not exposed to damage, or #6AWG when
exposed to potential damage.
Regards,
Gary Willett PE
Icarus Engineering LLC
On 10/28/14, 12:53 PM, Kirk wrote:
Hi,
I'm on a jobsite without my code book. Could someone tell me
where in the code ungrounded systems do not require the
inverter GEC? Basically my onsite electrician doesn't believe
me. Thanks.
Kirk Herander
VSE
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