BEFORE THE ARCHITECTE-PUBLICATIONS

Home Design Standards-Home Building Standards

Electrical Design Standards

Home Design Standards – Home Building Standards, 3Q10 Ed.      Page  386

ii)        including no interconnection whatsoever between a grounded conductor and a grounding conductor in a electrical distribution panel board, sub panel, junction box, electrical device, etc.

iii)      including no interconnection whatsoever between grounded conductors

 

Comment:  Sorry for all those shall nots; however, this home designer needs to close the loopholes.  Interconnecting grounded conductors is especially a condition this home designer’s seen in commercial and industrial  electrical wiring, along with several hot legs each relying on the same grounded conductor. 

Tragic consequences can come calling from these so-called “dirty neutrals”: AFCIs and GFCIs won’t work as designed with interconnected grounded conductors; electrical loading up a grounded conductor with several energized conductors can overheat the grounded conductor.

 

2)     Each electrical circuit wiring electrical load

a)     shall be judged as to whether it is continuous if

i)        it could reasonably supply continuously for 3 hours or more or

ii)      de facto, as in an electrical water heater of 120 gallon capacity or less

iii)    if daylight = 0%

iv)    if there are no windows in the load space

b)     if judged continuous, then it shall be derated by 20% (, or the peak electrical load multiplied by 1.25, please see  NEC2006 422.1) subsequent to all other deratings

 

Comment:  Usually, any given residential electrical load is not regarded as continuous.  Continuous electrical loads come into active play in commercial and industrial applications.  However, the AG knows full well that some electrical loads in a residence can operate frequently well beyond 3 hours continuously, e.g., some exterior home light and some interiors home light, entertainment centers, computer equipment, attic fans, etc. 

Check all specifications with your local building authority before construction. Permission to quote with attribution. © 2000-2010 by Before The Architect(s). All rights reserved. www.beforethearchitect.com  July 2010, 3rd Quarter Ed.

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