Class 1, Class 2, and Class 3
Remote-Control, Signaling, and Power-Limited Circuits
Medicine Chest That Bites?
Proposals Due Soon
Grounding vs Bonding Seminar
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Top 2005 Code Changes
Class 1, Class 2,
Class 3 Remote-Control, Signaling, and Power-Limited Circuits
By Mike Holt
Where necessary for their direct action upon, or
of the contained air, Class 2 and Class 3 cables can be installed in
ducts or plenum if they're installed in electrical metallic tubing,
intermediate metal conduit, or rigid metal conduit as required by
300.22(B). (Note: Code text has been paraphrased.)
What the Code says:
Plenums, and Other Air-Handling Spaces.
Ducts and Plenums. Class
and Class 3 cables installed within ducts or plenums must be installed
in accordance with 300.22. (Text new to the Code is
You can install nonplenum-rated Class 2 and Class 3 cables within
electrical metallic tubing, as permitted by 300.22(C), above a
ceiling or below a raised floor that is used for environmental air.
CL2 and Type CL3 cables installed beneath a raised floor in an
information technology equipment room (computer room) aren't required
be plenum rated [300.22(D) and 645.5(D)(5)(c)].
What the Code says:
Air-Handling Space. Plenum-rated Class 2 and Class 3 cables
and plenum signaling raceways [725.82(I)] with plenum-rated cables,
can be installed above a suspended ceiling or below a raised floor used
for environmental air movement [725.61(A)]. (Text new to the
Code is underlined.)
Behind the change: These changes clarify the types of cables
and raceways permitted in ducts, plenums, and other space used for
Achieve your performance goals
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
A Medicine Chest
Several years ago, my son complained he got "bit" while
reaching for his toothbrush in the medicine chest of our bathroom. He
was touching the water faucet at the time. While investigating this
claim, I discovered that the previous homeowners had removed an
light fixture when they installed the medicine chest. The light fixture
was no longer needed because the new metal medicine chest came with its
own lights. What I discovered was the previous owners had replaced the
old light fixture socket with a screw-in adapter for a two-prong plug.
The new medicine chest was connected to the adapter with simple lamp
cord. Over time, excess heat caused the lamp cord to become brittle.
Once the insulation cracked, it exposed the conductor, which made
contact with the ungrounded metal cabinet. I immediately replaced the
old lamp socket with a GFCI-type receptacle to eliminate the
Send your 200-word story to us and it may
appear in a future issue of CodeWatch. Authors of stories chosen will
Cool Electronic Cabinets
Low cost Cabinet Coolers stop electronic control downtime due to heat,
dirt and moisture. UL Listed Cabinet Coolers produce 20 degree
Fahrenheit air from an ordinary supply of compressed air to cool
electrical controls. Thermostat control 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
What's Wrong Here?
By Joe Tedesco
Got a guess for how this installation violates the NEC?
Web site to see the answer.
Hint: Cool splice for an air conditioner, huh?
By Mike Holt
Q. How close can I run underground service
conductors in a raceway to an outdoor pool?
Web site to see the answer.
By Steven Owen
Q.When grounding branch circuits -- with respect
to grounding requirements for receptacles and fixed equipment -- in
patient care areas of hospitals (critical care or general care areas),
which of the following statements is correct?
A) You can use an internal equipment grounding conductor of a
metallic raceway or cable, the metal of the metallic raceway, or a
metallic cable armor or sheath assembly to ground receptacles or fixed
B) You can only use a properly sized internal equipment
conductor within a metallic raceway.
C) You can only use a properly sized internal equipment
conductor in a nonmetallic raceway.
D) You can use any properly sized equipment bonding jumper
installed external to the wiring method of choice.
Web site for the answer and explanation.
The National Electrical Code Internet Connection, the No. 1
rated Code Web site in the world, offers the following FREE products:
Books, Code Quiz, DVDs, Graphics for PowerPoint, Newsletter, Online
Training, Posters, Simulated Exams, Software, Video clips, and Videos
Visit www.NECcode.com and stay
current with important industry issues.
Code News Updates
2008 Proposals Due
Seems like it wasn't all that long ago that you
your copy of the 2005 NEC, doesn't it? Well, guess what, the first
official step in creating the 2008 NEC occurs in just a few days. But
you better act fast. Code-making panels are soliciting change proposals
for just a few more days. Don't miss your chance to voice your concerns
about that requirement that's been bugging you. Change proposals are
by 5 p.m. on Nov. 4.
A copy of the proposal form is available in the back of the 2005 NEC
or at NFPA's
On July 29, the NFPA's Standards Council issued a
Tentative Interim Agreement (TIA) to the 2005 edition of the NEC, which
revises sections 680.26(C) and 680.26(C)(1). The changes are focused on
the equipotential bonding grid requirements for pools and paved walking
surfaces adjacent to a below-grade pool.
The TIA will become a proposal for the 2008 edition of the Code and
be subject to the procedures of the standards-making process at that
time. The effective date of the TIA will be Aug.18, 2006.
Shows and Events
Grounding and bonding of electrical systems, sensitive
electronic, and communications equipment is the most important and
understood activity in the electrical, data processing, and
communications industry. At four two-day seminars, Code expert Mike
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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