It feels like just the other day when I sat down to share my thoughts on the release of the 2011 edition of the National Electrical Code (NEC). Now, three years later, I’m shaking my head in disbelief as we put the final touches on this important issue. And similar to past years, there’s no shortage of revisions to review and discuss. So let’s jump right in. Here are some highlights.
As each of you should already know, the purpose of the Code is “the practical safeguarding of persons and property from hazards arising from the use of electricity.” To make this point even clearer, an additional sentence has been added to the introduction section, which notes the NEC is not a design specification or an instruction manual for untrained personnel. Beyond this simple but most important purpose clarification statement, 18 new definitions have been added to this edition.
In keeping with the last several revision cycles, the requirements for GFCI and AFCI protection have been expanded yet again. GFCI protection is now required for receptacles within 6 ft of bathtubs or shower stalls, in laundry areas, serving dishwashers, as well as on circuits serving tire inflation and automotive vacuum machine equipment. AFCI protection is now required for kitchens and laundry areas of dwelling units and in dormitory units.
In an effort to try and clear up the rules for sizing conductors, the requirements set forth for branch circuit, feeder, and service conductors have been simplified. These changes will hopefully set the record straight on exactly when in the calculation process one should factor in the adjustment and correction factors. Conductor ampacity requirements have also been modified. It’s now clear that spare conductors must be included in ampacity adjustment calculations. There is also a new 83% reduction reference for service and feeder conductors that should generate quite a bit of future discussion.
Of course there were also revisions made to various bonding and grounding requirements. A few of the more notable changes focus on grounding electrode conductor (GEC) installations and GEC bonding connection requirements. A new rule requires transformers to have a place to terminate grounding conductors. There’s also a new set of rules for bonding and grounding fences and other metal structures enclosing a substation.
Several new Articles were also added to this edition. Article 393 covers the installation of low-voltage suspended ceiling power distribution systems operating at 30V or less AC or 60V or less DC. Article 646 covers modular data centers. Article 728 covers the installation of fire-resistive cables, conductors, and other system components. Article 750 applies to the installation and operation of energy management systems.
There are also several changes that relate to DC power systems. There are new ungrounded conductor identification rules for branch circuits and feeders as well as sizing requirements for DC grounding electrode conductors and ground fault detection marking requirements for DC systems in Article 250. Numerous revisions were also made to Article 690, which applies to PV energy systems.
For a much more in-depth review of Mike Holt’s Top 20 revisions, turn to page 8 of this issue and find a nice quiet spot to spend some quality time soaking it all in. The initial prep work on your end will give you a great head start to mastering these new rules — long before this edition of the Code is adopted in your part of the world.