[RE-wrenches] Searchable, notable Code

Wed Nov 5 12:15:11 PST 2014

Friends:

We have been seeing a lot of good commentary here on code questions.  I need to be able to access these in the future at a time when I may not have thought about a specific issue for some time and need to be able to get my head around a concept in a hurry.  Searching the Wrenches archives is not an efficient method.  I need the information right in my copy of the code, at the exact location it applies.

My first electronic (PDF) version of the code from NFPA came packaged in a product called “Folio Viewer.”  This was a great product that allowed advanced search functions and sophisticated bookmarking.  Unfortunately this program is no longer available, a real shame.

We all have a need to markup our own versions of the code.  Currently I “break” the electronic protection of the PDF version using an on-line service (http://online2pdf.com/).  I can then create my own bookmarks, margin notes and links.  I add comments like those below using the ‘sticky notes’ function of Acrobat Pro and bookmark oft-used passages.  I also create links to cited sections, making it easier to navigate.

Does anyone else have suggestions as to how to retain notes and pertinent comments within the code?

William

Gradient Cap_mini
Lic 773985
 <http://www.millersolar.com/> millersolar.com
805-438-5600

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Rebekah Hren
Sent: Wednesday, November 05, 2014 9:55 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Code reference request

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> 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
dana at ecotechenergy.com
360.318.7646

On Mon, Nov 3, 2014 at 12:45 PM, August Goers <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

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
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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.

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