August 8, 2005 A PRIMEDIA Property Vol. III No. 15


CONTENTS
445.18 - Disconnecting Means

Hang Up and Try Again

What's Wrong Here?

Code Q&A

Code Quiz

Potential Problems

Grounding vs Bonding Seminar


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    Top 2005 Code Changes
    445.18 - Disconnecting Means
    By Mike Holt
    A change to this section permits a single generator to have multiple disconnecting means to allow flexibility and to provide a safer environment when maintenance is necessary. (Note: Code text has been paraphrased.)

    What the Code says:
    Generators must have one or more disconnecting means that disconnects all power, except where:
    (1) The driving means for the generator can be readily shut down, and
    (2) The generator isn't arranged to operate in parallel with another generator or other source of voltage.
    (Text new to the Code is underlined.)

    Behind the change: This rule is necessary because a single generator can be used to supply emergency, legally required, as well as optional standby power through different transfer switches. Be careful -- if one generator is used to supply emergency, legally required, as well as optional standby power, then there must be at least two transfer switches: one for emergency power and another for legally required as well as optional stand-by power [700.6(D)].


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    Nightmare Installations
    Hang Up and Try Again
    A few years ago, while upgrading a 100A service panel located in a residential garage, I noticed what appeared to be two black TW or THW wires about the size of 8 AWG entering the panel without conduit (a not-uncommon practice of do-it-yourselfers). As I removed the incoming wires for the replacement, I found that what I thought were THW wires were actually two very old 2-pair phone cables. The four 20 AWG phone wires in each had been twisted together and connected to a 2-pole, 30A breaker, which fed a garage. Why there had never been a fire, I have no idea. The only load on the circuit was a yard light, but there was evidence that there had been other lights and receptacles connected at one time. Needless to say, all was replaced.
    Roger Roossinck
    Sparta, Mich.


    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
    Got a guess for how this installation violates the NEC? Visit EC&M's Web site to see the answer.

    Hint: Recycling isn't always a good thing.

    Code Q&A
    By Mike Holt
    Q. What size grounding electrode conductor is required for a 1,200A service supplied with three sets of 600 kcmil conductors per phase?
    Visit EC&M's Web site to see the answer.

    Code Quiz
    By Steven Owen
    What's the minimum size THHN insulated conductor required for the power conversion equipment included as part of an adjustable speed drive system that uses a bypass device. The rated input of the power conversion equipment is 36A. The motor is rated 30 hp, 480VAC, 3-phase. The terminals at the power conversion equipment are rated 75°C.

    1. 10 AWG THHN
    2. 8 AWG THHN
    3. 6 AWG THHN
    4. 4 AWG THHN

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


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    Speak Out
    Potential Problems
    As Nightmare Installations shows, there's no shortage of shoddy electrical work. How often do you run across installations with Code violations when you perform service and maintenance work? Visit EC&M's Web site to tell us.

    "Get on with it!" That's what CodeWatch readers are saying about Code-making panels' approach to adding GFCI requirements to the NEC. Although less than one-third said the Code has adequately addressed the need for GFCIs, 40% said it was time to apply an across-the-board requirement for all receptacles.

    Shows and Events
    Grounding vs Bonding Seminar
    Grounding and bonding of electrical systems, sensitive electronic, and communications equipment is the most important and least understood activity in the electrical, data processing, and communications industry. At four two-day seminars, Code expert Mike Holt will explain the basics as well as the advance concepts necessary to understand the practical grounding and bonding rules in the NEC for systems not over 600V. Download the conference brochure for specific dates and locations.

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