By: Frederic P. Hartwell, Hartwell Electrical Services
EC-Online, your inside source for NEC information, brings you advance information on what's happening as work begins on the 2002 NEC. Over the next few weeks, we'll tell you what happened at the Hilton Head, S.C. meetings this past January. These results reflect the preliminary votes at the panel meetings, and not the written ballot. Only the written ballot reflects the official panel position. We'll revisit this information after the Technical Correlating Committee meeting. Some results may change at that point. For example, a proposed change in the Code with a code-making panel (CMP) majority short of the re-quired two-thirds will be reported as rejected. Look here for a special report in July on those changes.
What follows is solid, expert analysis from the author's viewpoint that goes beyond a simple recitation of the panel actions. Be sure to get a copy of the NEC Report on Proposals (published in mid July 2000 and available at no charge from NFPA) to see the actual text. NFPA also makes the material available over the Internet when the time comes. In addition, the ROP is merely the first step in creating the next NEC. With its publication, a public comment period opens until October 27, 2000, after which the panels recon-vene to review their actions. Then the entire record goes before the NFPA membership in May of 2001.
The bottom line? All of the changes covered here may change as the process unfolds, and other pro-posed changes that were rejected may be accepted after the receipt of comments. Get involved. It's our Code. Look at these articles as good code discussion and a source of assistance if you want to partici-pate in the comment process.
The first article in this 15-part series covered changes in format and style anticipated for the 2002 edition of the NEC. For this remaining article, we'll identify the proposed changes by the 2002 location and cita-tion style, with the 1999 NEC location following (if it differs), designated as "Old". That way you'll be able to get a better feel for what to expect in the next NEC.
Part 14, Articles 760—Appendix D
760.7. Some unfortunate cross references that crept into the 1999 rule for wiring fire alarm circuits extending beyond one building to Art. 225 have been corrected. Art. 225, if referenced in its en-tirety, includes building disconnect provisions that should never be applied to a fire alarm system. Power-limited fire alarm circuits that extend beyond one building and run outdoors shall either meet the installa-tion requirements of Parts B, C, and D of Article 800, (as in the 1999 NEC) or shall meet the installation requirements of Part A of Article 300, now changed from the former reference to Art. 225. Nonpower-limited fire alarm circuits that extend beyond one building and run outdoors shall meet the installation re-quirements of Part A of Article 300 (new) and the applicable sections of Part A of Article 225 (thereby ex-cluding the disconnect provisions in Part B).
760.21, 760.41. To increase reliability, fire alarm system power supplies, whether or not power limited, can't be supplied through a GFCI. The accepted panel actions contain FPNs pointing to a correlating exception in Sec. 210.8(A)(5) Ex. 3 regarding receptacles in dwelling unit basements. That ex-ception doesn't exist as of yet because CMP 2 rejected it. The basic rule would hold anyway, however, because 90.3 gives Chapter 7 preference over Chapter 2. Often household system power supplies con-sist of a transformer with a 15A 125V plug built into it. They are quite heavy, and to make sure they stay in place they also have a slot in a bracket that lines up with the center faceplate screw of a duplex recep-tacle. That inevitably raises the question of what to do with the vacant half of the duplex receptacle, since it won't have GFCI protection in an area that requires it. There are two simple solutions. The first is to use a single receptacle with a No. 6 fender washer under the upper screw, which will catch the transformer-mounting bracket nicely. The other way is to feed only the bottom screw of a duplex receptacle, and break the jumper tabs on both sides, permanently deenergizing the vacant portion of the receptacle.
760.54(A)(1) Ex. 1. This exception to the basic rule that power-limited fire alarm system wir-ing must be divorced from all power wiring is being modified. The exception allows for barriers between systems, as are commonly arranged in surface raceways. The exception also allows another raceway to serve as the barrier within an enclosure. The change adds "or in a continuous nonconductor, such as a porcelain tube or flexible tubing" to the list of separations allowable within an enclosure. This type of separation isn't new; it appears in 760.54(A)(1) Ex. 2(b)(1). However, the latter case is far more limited, requiring in effect 300V insulation on the cable, only applying at terminations, and the power circuit run-ning not over 150V to ground. The only substantiation on this proposal discussed aligning cable tray pro-visions (which it also does), and it needs wider review. Although correlating provisions exist in most lim-ited energy articles, this proposal only affects fire alarm conductors.
770.2 Optical Fiber Raceway. This definition dropped the restriction allowing only nonme-tallic optical fiber cables, now any can be used. On the other hand, the definition now effectively prohibits these raceways from carrying unlisted cables, typically in the form of outside plant cable. Use a conven-tional Chapter 3 wiring method (as covered in Sec. 770.50) if you must extend outside plant cable.
780.3. This section no longer refers to "a closed loop power distribution system." In so doing, code users avoid the erroneous conclusion that Art. 780, in all the other places where it does not ex-pressly mention closed loop systems, actually applies to other programmed power systems that are not closed loop. Art. 780 only covers "smart house" (so-called) systems controlled by "a signaling between the energy controlling equipment and utilization equipment" [emphasis supplied]. Programmed power systems that address intelligent devices are outside to the scope of this article. Type NMS cable, which has a tie to Sec. 780.5 of this article, should only be used for programmed power arrangements upon a showing that there is sufficient system separation to meet the rules in Sec. 725.54(a)(1). The ex-ceptions throughout the Code that refer to Art. 780 are there on the assumption that they are addressing true closed loop distributions, which don't actually exist at this time because the technology failed in the market.
800.40(A)(4) and Ex. (new). For the first time a length restriction, of sorts, is heading into the NEC for communications grounding conductors. This discussion concerns Art. 800, but other propos-als affect Art. 820 and 830 in a similar fashion. For all occupancies, the primary protector-grounding con-ductor must be as short as practicable, and for one- and two-family "residences" it must not exceed 20 ft. If that dimension doesn't work in a single or two-family home, then drive one of the communications sys-tem ground rods (1/2 in. by 5 ft minimum), connect to that, and then bond that electrode to the power system electrode.
The proposal addresses concerns about excessive inductance in long grounding electrode conductors prior to the first point of earth contact, and how that might affect a steep (di/dt) wave front from a lightning strike. The length restriction in the proposal was limited to one- and two-family "residences" (obviously improper terminology) because "it is such installations that are more likely to have diverse power and communications entrances and experience lightning-related problems (urban/suburban environment with fewer elevated structures and extensive buried metallic objects)." These assumptions obviously require careful reexamination.
800.40(B)(1)(b). Interior metal water piping is no longer a qualified grounding electrode for communications systems. Correlating changes are on tap for Art. 810, 820, and 830. The only legal con-nection will be to the same area as for power system connections, that is, to the portion of the metal pip-ing system within the first 5 ft from the point of building entrance.
800.48. Metal communications raceways must now be grounded "as required by 250.86." This is an intriguing cross reference because it [via 250.112(I)] exempts all Chapter 7 limited energy arti-cle wiring from grounding, unless such circuits require system grounding, as, for example, when the sup-ply transformer primary is over 150V to ground. This section never mentioned Chapter 8 for the simple reason that Sec. 90.3 never imposed Chapter 2 grounding requirements on Chapter 8 installations. The result will overturn generations of settled practice regarding this work. Note that equivalent wording in this case does not appear in the other Chapter 8 articles.
820.10(B) Ex. To correlate with 800.10(A)(4), this provision now includes a minimum intersystem drop spacing (12 in.) and a minimum 40-in. climbing space provision at the pole. Usually the pole spacing is addressed by the communications utilities, although not necessarily. In addition, the drop spacing can be easily overlooked if the point-of-attachments are such that the cables don't run in parallel, but rather cross under one another.
830.10(e), 11(d). The specific spacing rules from swimming pools, for network-powered broadband communications circuit conductors running both overhead and below grade, are coming out of these sections entirely. Sec. 680.8 and 680.10 have been correlated as part of the Art. 680 rewrite to ac-commodate this material.This is the end of this 15-part series on the code making panel proposal meetings for the 2002 NEC. Watch for a follow-up article shortly covering major Technical Correlating Committee actions that affect the topics covered in this series. Then, right after the Report on Proposals actually mails (mid July), we'll summarize the most important of these actions in a 4-part series "The 100 Most Important Proposals for the 2002 NEC."
Acknowledgements
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About the author… (Back to top)
EC Online columnist and nationally recognized NEC expert Fred Hartwell is widely recognized as one of the most prolific contributors to the NEC, with nearly one thousand proposals and comments over the years making it into print. He has three code cycles experience on one of the code making panels. He has many years of contracting experience in Illinois and Massachusetts. He also served as an electrical inspector for fifteen years and he was head electrician on a college campus.
