[RE-wrenches] Code reference request
boB at midnitesolar.com
boB at midnitesolar.com
Wed Nov 5 12:25:32 PST 2014
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 <dana at ecotechenergy.com
> <mailto:dana at ecotechenergy.com>> 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>
> dana at ecotechenergy.com <mailto:dana at ecotechenergy.com>
> 360.318.7646
>
> On Mon, Nov 3, 2014 at 12:45 PM, August Goers <august at luminalt.com
> <mailto:august at luminalt.com>> 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:re-wrenches-bounces at lists.re-wrenches.org
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] *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>
> dana at ecotechenergy.com <mailto:dana at ecotechenergy.com>
> 360.318.7646 <tel:360.318.7646>
>
> On Tue, Oct 28, 2014 at 11:30 AM, Rebekah Hren
> <rebekah.hren at o2energies.com
> <mailto:rebekah.hren at o2energies.com>> 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
> <Gary at icarussolarservices.com
> <mailto:Gary at icarussolarservices.com>> 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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> http://o2energies.com/
> Project Engineer
> NABCEP Certified PV Installation Professional^(TM) 091209-85
> NC Licensed Electrical Contractor
>
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>
> --
> Tel: 336.266.8800
> http://o2energies.com/
> Project Engineer
> NABCEP Certified PV Installation Professional^(TM) 091209-85
> NC Licensed Electrical Contractor
>
> This message, together with any attachments, is intended only for the
> named recipient(s). It may contain confidential or privileged
> information that may be exempt from disclosure under applicable law.
> If you are not the intended recipient(s), you are notified that the
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