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The designations "National Electrical Code” and “NEC” refer to the
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Product of the Year Competition
Final Week of Voting!
Do you want the opportunity to win $100? Then visit the
EC&M Web site by June 30 to
your vote in EC&M's Product of the Year competition and help us
to identify the best new product introduced for the electrical industry
When you visit the EC&M Product of the Year
page, an automatic poll will pop up. (Note: If you have a pop-up
blocker program, it may prevent you from seeing the poll. Temporarily
disable the program to allow the poll to appear on your computer.) You
then need to type in your contact information, choose your favorite
product, and click submit. It's that simple.
A panel of nine judges narrowed the field from 114 entrants to 24
category finalists, and now we need your help to determine the Platinum
Award winner. The competition has honored innovation and excellence in
product development in the electrical industry for the past six
Anticipate, prevent and troubleshoot motors, electrical and equipment
maintenance with fast, accurate non-contact temperature measurements
with Fluke infrared thermometers. www.fluke.com/codewatch_temp
Top 50 NEC Rules
By Mike Holt
Size branch-circuit conductors no less than 125% of the
continuous loads plus 100% of the noncontinuous loads they serve, based
on the terminal temperature rating ampacities listed in Table 310.16,
before applying any ampacity adjustment [110.14(C)]. Where the assembly
and the overcurrent protection device are both listed for 100%
continuous load operation, the branch-circuit conductors can be sized
100% of the continuous load. Equipment suitable for 100% continuous
loading is rarely available in ratings under 400A.
Fine Print Note No. 4 discusses voltage drop. Although the NEC
doesn't consider voltage drop to be a safety issue, except for fire
pumps (695.7), size branch-circuit conductors to prevent a voltage drop
not to exceed 3%. This will ensure reasonable efficiency of operation
electrical equipment. In addition, don't allow the maximum total
drop on feeders and branch circuits to exceed 5%.
Conductor voltage drop can be determined by multiplying the current
flowing through the circuit by the resistance of the circuit
Voltage drop = I x R. Where (I) is equal to the load in amperes and (R)
is the resistance of the conductor [Chapter 9, Table 8 for direct
current circuits, or Chapter 9, Table 9 for alternating-current
circuits]. For three-phase circuits, simply adjust the single-phase
voltage drop value by a multiplier of 0.866.
Branch-circuit conductors that supply more than one receptacle for
cord-and-plug connected portable loads must have an ampacity no less
than the rating of the circuit [210.3 and 240.4(D)].
Branch-circuit conductors that supply household ranges, wall-mounted
ovens, or counter-mounted cooking units must have an ampacity no less
than the rating of the branch circuit and no less than the maximum load
to be served. For ranges of 8.75kW or more rating, the minimum
branch-circuit ampere rating must be 40A. Note the Code does offer a
exceptions to this rule.
Branch-circuit conductors must have an ampacity sufficient for the
loads served and must not be smaller than 14 AWG. An exception notes
that tap conductors must have an ampacity no less than 15A for circuits
rated less than 40A and no less than 20A for circuits rated at 40A or
50A for the following loads: individual outlets, other than receptacle
outlets, with taps no more than 18 inches in length. Note that
branch-circuit tap conductors aren't permitted for receptacle outlets.
Editor's note: This information was extracted from Mike
the National Electrical Code
Cool Electronic Cabinets
Beat the heat and prevent hot weather failures. UL Listed Cabinet
Coolers from EXAIR produce 20 degree Fahrenheit air from an ordinary
supply of compressed air to cool electrical controls. Thermostat
minimizes air usage. Maintains the NEMA 4, 4X (stainless steel) and 12
rating of the enclosure. Web site offers detailed information,
downloadable drawings and PDF literature.
What's Wrong Here?
By Joe Tedesco
Think you know how this installation violates the
NEC? Visit EC&M's Web
site to see the answer.
Hint: Go ahead and throw on another coat of paint.
By Mike Holt
Q. When determining the placement for
in a dwelling, is the wall space behind a door required to be
Web site to see the answer.
By Steven Owen
Q. What is the minimum acceptable voltage at a
fire pump motor's terminals, when the 460V-rated motor is supplied with
an operating voltage of 480V, and the motor is operating at 115% of the
full-load current rating of the motor?
Web site for the answer and explanation.
One Gets It Done.
Feel the difference with the Twister® Wire Connector. A
swept wing design provides added leverage, while the durable
polypropylene shell expands for a smooth application. The patented
live-action, square-wire spring locks onto the wire for safe, secure
connections. Don't settle for just any wire connector. Insist on the
Twister. Visit www.idealindustries.com
for a free sample.
Code News Update
Neutral Conductor Defined
According to the May 2006 issue of
Electroindustry, a task group appointed by the NEC Technical
Correlating Committee agreed on a recommended definition of the term
"neutral conductor." This new definition was presented to, slightly
modified, and accepted by Code Making Panel 5 during the proposal stage
of the 2008 NEC revision process.
The final accepted definition reads as follows: "The conductor
connected to the neutral point of a system that is intended to carry
current under normal conditions." A supporting definition for the term
"neutral point" reads as follows: "The common point on a wye-connection
in a polyphase system or midpoint on a single-phase, 3-wire system, or
midpoint of a single-phase portion of a 3-phase delta system, or a
midpoint of a 3-wire, direct current system."
The new definitions must still pass through several stages of
approval before being finally accepted for inclusion in the 2008
of the NEC.
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