June 8, 2005 A PRIMEDIA Property Vol. III No. 11


CONTENTS
334.80 -- Ampacity

Blame the Plumber

What's Wrong Here?

Code Q&A

Code Quiz

NFPA Solicits Proposals for 2005 NEC

Committee Call-Up

Who's Your Number Two?


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    Top 2005 Code Changes
    334.80 -- Ampacity
    By Mike Holt
     A new paragraph requires conductors to have their ampacity adjusted when more than one NM cable is bundled together as they pass through fire- or draft-stopped barriers. (Note: Code text has been paraphrased.)

    What the Code says:
    Conductor ampacity is calculated in accordance with 310.15 based on 90ºC conductor insulation rating, provided the adjusted or corrected ampacity doesn't exceed that for a 60°C rated conductor.
    Where more than two NM cables containing two or more current-carrying conductors are bundled together and pass through wood framing that's to be fire- or draft-stopped using thermal insulation or sealing foam, the allowable ampacity of each conductor must be adjusted in accordance with Table 310.15(B)(2)(a).     (Text new to the Code is underlined.)

    Behind the change: This requirement originates from studies that show cable temperatures could exceed their 90°C insulation rating when loaded circuits are brought into close proximity to each other inside a fire- or draft-stop. These areas can restrict heat dissipation. Note: This new requirement only applies to wood framing members, and has no effect unless you bundle more than nine current-carrying conductors together.

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    Nightmare Installations
    Blame the Plumber
    After 25 years in the service business, I've realized you never see it all. A customer once called me and explained when she turned the water on in the kitchen sink her door chime would ring. Of course I said I'd be right over because I had to see this one first hand. Sure enough she turned on the water and the chime went off. My first thought was a possible grounding problem with the cold water bonding. I tested the grounding system and the chime system with no luck. Never one to give up, I explained I needed to sleep on it. The next day I returned and asked the customer if it would ring when she turned on the cold water, the hot, or both. She didn't know so we tested it, and it only rang with the hot water on. Then I asked if she'd recently had any plumbing work done, and it turned out she'd had the whole house repiped. I went into the attic and found the problem. The new hot water line was laying across the front door button wiring. When the hot water was turned on and the pipe heated up, the connection was made. The plumber had slightly nicked the insulation on the bell wire during the pipe installation, but it only made contact between the two conductors when the hot water was turned on.
    Greg Charrier
    Huntington Beach, Calif.
    Send your 200-word story to us and it may appear in a future issue of CodeWatch. Authors of stories chosen will receive $25.

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    Code Challenge
    What's Wrong Here?
    By Joe Tedesco
     How does this installation violate the NEC?

    Hint: This fitting is permitted when making this transition, but...
    Code Q&A
    By Mike Holt
     Q. Does the NEC restrict the placement of a light switch in a bathroom? What about pools, spas, and hot tub areas?
    See the answer.
    Code Quiz
    By Steven Owen
     Those who design lighting systems for the spectator seating area of indoor sports arenas have expressed concern about the possibility of luminaires suffering damage during play and putting spectators at risk. According to the 2005 NEC, what's the correct choice for this application?

    1. A high-bay type luminaire with an open bottom and a manufacturer-installed lens to protect people beneath the luminaire from any broken or shattered glass. This luminaire uses a standard metal-halide lamp
    2. A high-bay type luminaire that uses a standard metal-halide lamp and a manufacturer-installed wire guard that consists of #9 wire
    3. A high-bay type luminaire that uses a standard metal-halide lamp and an open bottom
    4. The NEC doesn't include a requirement of any type for this installation

    Visit EC&M's Web site for the answer and explanation.

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    Code News Updates
    NFPA Solicits Proposals for 2005 NEC
    Seems like just yesterday that you received your copy of the 2005 NEC, doesn't it...so what better time than now to start thinking about making changes? Code-making panels are soliciting change proposals for the 2008 NEC, so now's your chance to voice your concerns about that requirement that's been bugging you. Proposals are due by 5 p.m. ET on Nov. 4. A copy of the proposal form is available in the back of the 2005 NEC or at NFPA's Web site.
    Committee Call-Up
    If you've got some extra time to spare and a desire to get involved with NFPA standards other than the NEC, two committees are looking for members. The Committee on Electrical Equipment of Industrial Machinery (NFPA 79) and the Committee on Electrical Systems Maintenance (NFPA 73) are seeking new members in most categories. You can download an application from NFPA's Web site.

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    Speak Out
    Who's Your Number Two?
    The NFPA 70 series of standards (70, 70A, 70B, and 70E) gets most of the press in the electrical industry, but several other NFPA standards are devoted to aspects of the electrical industry. Which of these "other" standards do you use the most? Visit EC&M's Web site to tell us.

    If a state or local government wants to amend the Code, it's their prerogative, but the majority of CodeWatch readers (62%) think they should leave well enough alone.

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