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

billbrooks7 at sbcglobal.net billbrooks7 at sbcglobal.net
Wed Mar 2 11:24:29 PST 2016


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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