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

[Christopher Warfel]

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] 
> *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 <mailto:august at luminalt.com>
> *Sent: *‎3/‎2/‎2016 11:32
> *To: *RE-wrenches <mailto: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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