[RE-wrenches] Code reference request

Mon Nov 3 12:45:09 PST 2014

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

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] *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
dana at ecotechenergy.com
360.318.7646

On Tue, Oct 28, 2014 at 11:30 AM, Rebekah Hren <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>
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
_______________________________________________
List sponsored by Redwood Alliance

List Address: RE-wrenches at lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

_______________________________________________
List sponsored by Redwood Alliance

List Address: RE-wrenches at lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

-- 

Tel: 336.266.8800
http://o2energies.com/
Project Engineer
NABCEP Certified PV Installation Professional™ 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 disclosure, dissemination,
distribution, copying, storing, or other use of the contents of this
message or its attachments is strictly prohibited.  If you receive this
message in error, or are not the named recipient(s), please notify the
sender at either the email address or telephone number above and delete
this email from your computer.  Thank you.

_______________________________________________
List sponsored by Redwood Alliance

List Address: RE-wrenches at lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20141103/822f5ab4/attachment-0003.html>