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

[Howie Michaelson]

Bill,
Did I understand your earlier post to infer that there never was an intent
to apply the "opposite end of the buss" rule to the 120% backfeed allowance
in residential applications?  And that you have been working to rewrite a
solar backfeed breaker in a residential setting to land anywhere on the
buss?

Howie
*Howie Michaelson*
*NABCEP Certified Solar PV Installer™*
Sun Catcher, LLC
Renewable Energy Systems Sales and Service
VT Solar Electric Incentive Partner
802-272-0004

On Thu, Mar 3, 2016 at 12:07 PM, <billbrooks7 at sbcglobal.net> wrote:

> Phil,
>
>
>
> I think you already understand how to apply the “120% rule.” All this is
> saying is that the breaker can go at either end of a center-fed panel for
> dwellings. Do you understand now?
>
>
>
> To summarize—a 200A center-fed panel would allow a 40-amp PV breaker to be
> installed at either end to meet the 120% rule.
>
>
>
> Bill.
>
>
>
> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
> Behalf Of *Philip Lawes Insoltech
> *Sent:* Thursday, March 03, 2016 8:26 AM
> *To:* 'RE-wrenches' <re-wrenches at lists.re-wrenches.org>
> *Subject:* Re: [RE-wrenches] NEC 705.12 Point of Connection - 120% rule
> for center-fed panelboards
>
>
>
> Bill,
>
> Could you please provide an example of this showing calculations?
>
> Thanks so much,
>
> Phil
>
>
>
> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org
> <re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of *
> billbrooks7 at sbcglobal.net
> *Sent:* Wednesday, March 2, 2016 11:24 AM
> *To:* 'RE-wrenches' <re-wrenches at lists.re-wrenches.org>
> *Subject:* Re: [RE-wrenches] NEC 705.12 Point of Connection - 120% rule
> for center-fed panelboards
>
>
>
> 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>
> *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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