[RE-wrenches] NEC 705.12 Point of Connection - 120% rule for center-fed panelboards

August Goers august at luminalt.com
Sat Mar 5 09:25:29 PST 2016


HI All -

Thanks for the good input. I suppose it will be up to each of us to work
with our local AHJs to determine the fate of PV and center-fed panelboards.
In CA we're we won't be under the 2014 NEC until 2017 and the 2017 NEC
won't kick in until 2020. We have a ways to go before getting clear code
guidance under the new 2017 language that Bill posted. As PV goes more and
more mainstream I'm seeing the general AHJ awareness of these once-obscure
code questions go higher. Many AHJs just go by the most conservative view
of the NEC and won't budge on these types of issues. They will side with
John Wiles' interpretation. All that said, I will certainly work with some
of our local Bay Area AHJs to see if they will be willing to look forward
to the 2017 NEC language and accept the 120% rule for center-fed
panelboards. I'll report back if I make progress.

Cheers,

August

*August Goers*

Luminalt Energy Corporation

o: 415.641.4000

m: 415.559.1525

www.luminalt.com



On Fri, Mar 4, 2016 at 9:38 AM, Abe Powell <abe at solforce.com> wrote:

> I support Bill's assertion here and his work on the code making committee.
>
> Certain AHJ's in California are obsessing about center-fed residential
> panels.  (County of Santa Barbara, for example)  The result is unnecessary
> meter-main panel upgrades.  These upgrades drive the cost of solar
> installations up significantly ($2000-$4000.)  This added cost acts as
> barrier-to-entry into the solar market.
>
> The problem with all of this is that *center-fed residential panels are
> not a safety problem to begin with.  *
>
> Thus, we get:  A) increased cost, B)  fewer solar installations and C) no
> improvement in overall safety.
>
> Put simply, *this is a lose-lose situation that needs to be addressed now*,
> because adoption of the 2017 code is a long way away for most of us.
>
> Best regards,
>
> Abe
> -----------------------------
> John Abraham Powell
> CEO
> Solforce
> W. 805/695-0015
> C. 805/895-2355
> E. abe at solforce.com
> www.solforce.com
> CA License. 806685
>
>
>
> On Thu, Mar 3, 2016 at 12:40 PM, <billbrooks7 at sbcglobal.net> wrote:
>
>> Chris,
>>
>>
>>
>> While John’s article may seem like a logical interpretation of the 2014
>> NEC, if you lived in the western half of the United States where these
>> panels are common, you would have a very different view of his choice of
>> articles.
>>
>>
>>
>> His article sites a technicality that is not a safety concern in the
>> least. Of all the things that AHJs have to worry about with PV, this has to
>> be at the very bottom of the list—and yet this is the only thing that many
>> AHJs look at because someone wrote an article about it. We set the record
>> straight in the 2017 NEC, but that does not fix the fact that literally
>> 1,000s of these perfectly fine panels have been removed due to the focus of
>> this magazine article.
>>
>>
>>
>> Your opinion of this interpretation would be very different if you had
>> lost a PV system sale because someone was unwilling to incur the extra cost
>> of a panel change out when you knew it was totally unnecessary.
>>
>>
>>
>> I have all the respect in the world for what you are doing in the
>> northeast. I’m just helping with some “perspective” from the left coast.
>>
>>
>>
>> I’m off my high horse,
>>
>>
>>
>> Bill.
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
>> Behalf Of *Christopher Warfel
>> *Sent:* Thursday, March 03, 2016 6:42 AM
>> *To:* re-wrenches at lists.re-wrenches.org
>> *Subject:* Re: [RE-wrenches] NEC 705.12 Point of Connection - 120% rule
>> for center-fed panelboards
>>
>>
>>
>> This is a link to John Wiles article on NEC2014 for this topic. To my
>> knowledge, no one has adopted NEC2017, so it would seem that this article
>> is appropriate for the most recent NEC published. As noted AHJs can allow
>> exceptions, and it is great that new language is now approved for NEC2017,
>> but that wasn't the case when John Wiles published his article.
>>
>>
>> http://iaeimagazine.org/magazine/2014/07/10/center-fed-load-centers-and-panelboards/
>>
>> There is also pdf version here.
>>
>>
>> https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwjl8OmH26TLAhWI7D4KHcbJAHQQFggjMAE&url=http%3A%2F%2Fdept-wp.nmsu.edu%2Fswtdi%2Ffiles%2F2015%2F11%2Fiaei_jul-aug_2014.pdf&usg=AFQjCNERV2M21V1nvLlvLVSLZUMoj36J_A&sig2=g145SdF1HzNuHc0P6NXshw&bvm=bv.115339255,d.cWw&cad=rja
>>
>>
>> Chris
>>
>>
>> On 3/2/2016 2:24 PM, billbrooks7 at sbcglobal.net wrote:
>>
>> All,
>>
>>
>>
>> Here is the new language that has been approved for the 2017 NEC (more
>> authoritative than JW).
>>
>>
>>
>> 705.12(B)(3)(d)
>>
>>
>>
>> (d) A connection at either end, but not both ends, of a center-fed
>> panelboard in dwellings shall be permitted where the sum of 125 percent of
>> the power source(s) output circuit current and the rating of the
>> overcurrent device protecting the busbar does not exceed 120 percent of the
>> current rating of the busbar.
>>
>>
>>
>> This clarifies that it was never the intent of the NEC to limit the 120%
>> rule to the opposite end of the busbar for dwellings (it was allowed from
>> 2005 back to 1987). I was able to convince the panel that centerfed panels
>> did not need the opposite end stipulation. Several large jurisdictions in
>> California or considering making an official policy accepting the language
>> of the 2017 NEC on this item. Please share this with your own jurisdiction.
>>
>>
>>
>> Bill.
>>
>>
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org
>> <re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of *Glenn Burt
>> *Sent:* Wednesday, March 02, 2016 10:54 AM
>> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
>> <re-wrenches at lists.re-wrenches.org>
>> *Subject:* Re: [RE-wrenches] NEC 705.12 Point of Connection - 120% rule
>> for center-fed panelboards
>>
>>
>>
>> I believe that John Wiles has stated this in a couple of places in print,
>> therefore you may have a tough time justifying a way around the rule to an
>> AHJ.
>>
>> Supply side connections are very popular in this situation.
>> ------------------------------
>>
>> *From: *August Goers <august at luminalt.com>
>> *Sent: *‎3/‎2/‎2016 11:32
>> *To: *RE-wrenches <re-wrenches at lists.re-wrenches.org>
>> *Subject: *[RE-wrenches] NEC 705.12 Point of Connection - 120% rule for
>> center-fed panelboards
>>
>> All –
>>
>>
>>
>> We are seeing more AHJs not allowing us to use the NEC
>> 7015.12(D)(2)(3)(b) 120% rule on center-fed panelboards. For example, if we
>> have a 100 A meter/main combo with a center fed 100 A breaker we cannot
>> apply the 120% rule at all and need to do a panel swap. What are other
>> wrenches doing in this case?
>>
>>
>>
>> Best,
>>
>>
>>
>> August
>>
>> Luminalt
>>
>>
>>
>>
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>>
>> --
>>
>> Christopher Warfel, President
>>
>> ENTECH Engineering, Inc.
>>
>> PO Box 871, Block Island, RI 02807
>>
>> 401-466-8978
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>>
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