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

Thu Mar 3 12:40:08 PST 2016

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 <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> &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 <mailto: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  <mailto: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 <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
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