[RE-wrenches] 705.95(B) and Sunny Boys - current on Neutral?

Fri Nov 29 18:21:26 EST 2019

Thanks for your reply Mike. -  Yes we understand all of this but why make it hard for the AHJ to in the field?  A little manufacturer support here would be helpful. If two of us wrenches had the same reaction to the wording might the AJH not also be confused?  

Sent from my iPhone

> On Nov 29, 2019, at 1:06 PM, Harry Mahon <Michael.Mahon at sma-america.com> wrote:
> 
> Please see the third and fourth paragraph under ‘Neutral Specifications’ for the description of operation of the Sunny Boy US -40/-41 family.
>  
> The third paragraph is correct for ALL Sunny Boy models, that is why no model numbers are called out.  This paragraph states what you are looking for: that the neutral is NOT a current carrying conductor.
>  
> The fourth paragraph calls out the Sunny Boy US-40/-41 specifically as it can work on 240 or 208 delta services where there is no neutral conductor available. This is not supported by any other inverter referenced by the document. And this is why the third paragraph is worded “WHEN connecting two ungrounded AC conductors and a single grounded conductor to the Sunny Boy..” – it covers the Sunny Boy US-40/-41 WHEN attaching to a grounded service.
>  
> If there is any confusion by an inspector, SMA will be happy to clarify why the document is worded this way.
>  
> The “X” is to indicate that the specific inverter will support attachment to the utility service listed.  That could be explicitly called out, I will pass that feedback on.
>  
> Best regards -
> Mike
>  
>  
> SMA America
> Michael Mahon
> Technical Trainer, Solar Academy
> 6020 West Oaks Boulevard, Suite 300
> Rocklin, CA 95765
> U.S.A.
> Mobile:   +1 916 918 9412
> www.SMA-America.com
>  
> Solar Academy: https://solaracademy.sma.de/en.html
>  
> SMA America Solar Academy webinars:
> https://solaracademy.sma.de/en/courses.html
> Choose "English" and "Online" as filters.
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>  
> This email and any attachments thereto may contain SMA America, LLC confidential, privileged and private material for the sole use of the intended recipient. Any review, copying, or distribution of this email (or any attachments thereto) by others is strictly prohibited. If you are not the intended recipient, please contact the sender immediately and permanently delete the original and any copies of this email and any attachments thereto. Thank you.
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> From: Jeff Clearwater <jeffc at villagepowerdesign.com> 
> Sent: Tuesday, November 26, 2019 2:13 PM
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>; scot.arey at solarcentex.com
> Cc: Harry Mahon <Michael.Mahon at sma-america.com>
> Subject: Re: [RE-wrenches] 705.95(B) and Sunny Boys - current on Neutral?
>  
> Hi Scot and Mike,
> 
> Yes It is terribly worded - an AHJ could easily read it and come away with the impression that only the TL and TriPower required the neutral only for instrumentation and voltage and phase detection - implying the rest used the neutral for current.
> 
> And your right what do the x's even mean?
> 
> I see the SMA author to be Chris Schwegler authored on July 19th, 2019.  Mike, can you send back to him for a re-write as this won't hold it's water to AHJs going forward.
> 
> Thanks!
> 
> Jeff
> 
> 
> scot.arey at solarcentex.com wrote on 11/26/19 6:42 AM:
> 
> 
> Mike,
>  
> Thanks for posting the note, but I find the wording to be less than fully clear. According to this note, the “The transformer-less series of inverters named Sunny Boy TL-US-12, Sunny Boy TL-US-22 and Sunny Tripower 12/15/20/24000TL-US-10  have a neutral connection that is required at installation for instrumentation, voltage and phase detection only.”
>  
> There is no mention of the -41 inverter also using the neutral for reference only, even though the note is “applicable to the following inverter types” and that shows the -41
> 
> Also, the table has these green x marks but no annotation of what the green x indicates.
> 
> Can you clarify, please?
>  
>  
> <image016.png>
>  
>  
>  
> From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> On Behalf Of Harry Mahon
> Sent: Thursday, November 14, 2019 11:02 AM
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>; Jeff Clearwater <jeffc at villagepowerdesign.com>
> Subject: Re: [RE-wrenches] 705.95(B) and Sunny Boys - current on Neutral?
>  
> Lloyd – great find!
>  
> I am attaching a updated note that specifically calls out current products but has less code detail.
>  
> Best regards –
> Mike
>  
> SMA America
> Michael Mahon
> Technical Trainer, Solar Academy
> 6020 West Oaks Boulevard, Suite 300
> Rocklin, CA 95765
> U.S.A.
> Mobile:   +1 916 918 9412
> www.SMA-America.com
>  
> Solar Academy: https://solaracademy.sma.de/en.html
>  
> SMA America Solar Academy webinars:
> https://solaracademy.sma.de/en/courses.html
> Choose "English" and "Online" as filters.
>  
>  
> <image009.jpg><image010.jpg> <image011.jpg> <image012.jpg> <image013.jpg> <image014.png> 
> <image015.jpg>
>  
>  
> This email and any attachments thereto may contain SMA America, LLC confidential, privileged and private material for the sole use of the intended recipient. Any review, copying, or distribution of this email (or any attachments thereto) by others is strictly prohibited. If you are not the intended recipient, please contact the sender immediately and permanently delete the original and any copies of this email and any attachments thereto. Thank you.
>  
> From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> On Behalf Of Lloyd Hoffstatter
> Sent: Wednesday, November 13, 2019 10:38 AM
> To: Jeff Clearwater <jeffc at villagepowerdesign.com>; RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: Re: [RE-wrenches] 705.95(B) and Sunny Boys - current on Neutral?
>  
> Jeff,
>  
> An oldie but attached tech note explains.
> May Need to upsize G / N  for voltage drop depending on run…
>  
> Best regards,
>  
> Lloyd
>  
> Lloyd Hoffstatter
> Sunstruck Consulting
>  
> Sent from Mail for Windows 10
>  
> From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on behalf of Jeff Clearwater <jeffc at villagepowerdesign.com>
> Sent: Wednesday, November 13, 2019 12:00:37 PM
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] 705.95(B) and Sunny Boys - current on Neutral?
>  
> Hey Folks,
> 
> So does anyone have a reference I can show my AJH as to whether there is any current on the neutral of a single phase 240 VAC SB 7.7-40 inverter?
> 
> 705.95(B) states:
> 
> Neutral Conductor for Instrumentation, Voltage
> Detection or Phase Detection. A conductor used solely for
> instrumentation, voltage detection, or phase detection and
> connected to a single-phase or 3-phase utility-interactive
> inverter, shall be permitted to be sized at less than the
> ampacity of the other current-carrying conductors and shall
> be sized equal to or larger than the equipment grounding
> conductor.
> 
> Be great not have to run 3/0 wire to my dedicated PV subpanel with 5 SB7.7s.  At 200 Amps I could use 6 AWG according to 705.95.  A huge savings in wire pull hassle not to mention copper.
> 
> Are there any other practical considerations for those SBs to operate well if I were to go that low with the neutral?
> 
> Anybody have any field experience with AJHs on this?
> 
> Thanks,
> 
> Jeff
> 
> ~~~~~~~~~~~
> Jeff Clearwater
> Village Power Design
> linkedin 
> www.villagepowerdesign.com
> cell - 413-559-9763
> ~~~~~~~~~~~~~~~~~~~~~~~
> 
> 
> 
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