| CONTENTS
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South Paw
Shocker
Hot Wax
Code
Calculations
What's
Wrong
Here?
Code Q&A
Code Quiz
Faces of the Code
Above and
Beyond
EC&M Code Conferences
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Nightmare Installations
South Paw Shocker
Several years ago on a job the GC told
me that every time the plumbing foreman came into his trailer he
complained of getting shocked by the door knob. We thought that this
was
odd because he was the only one on the job who ever made this
complaint.
I got out my meter and checked for signs of stray voltage, but not sure
what I was looking for, I didn't know where to start. I checked the
door
knob with every metal thing within 10 feet but to no avail. The GC said
something about it again the next day, so I decided to try the meter
again. About halfway through I got 98V to the hand rail, which was part
of the freestanding metal stair to the door. I found that a baseboard
heater wire was stripped and against the frame of the trailer, which
was
on rubber tires. After talking to the plumber, I learned that he was
left handed and always held the handrail when reaching for the door. He
was the only left handed worker to enter the trailer, so he was the
only
one to hold the rail while opening the door. We called him "missing
link" from that point on.
Jay LeFevre
Arvada, Colo.
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Hot Wax
I went out on a service call to repair a non-working
exit light in a grocery store. It was a thick light with cooling air
holes on the top and bottom. I looked for the conduit that supplied the
light to trace it back to the emergency lighting panel, but I couldn't
find it. Finally I got a ladder off my truck and took the light apart.
Inside I found a burned down stub of a votive candle. It turns out the
fixture had been installed with no guts and a lit candle to pass
inspection eight years earlier. I then piped and wired it as it should
have been done in the first place.
Dale LaPointe
Walled Lake, Mich.
Send your 200-word story to us and it may
appear in a future issue of CodeWatch. Authors of stories chosen for
publication will receive $25.
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Applications Corner
Code Calculations
When installing conductors of different sizes (or types
of insulation) in a raceway, you can't size the raceway based on Tables
1 through 12 in Annex C. You must instead follow this three-step
process
to determine the proper raceway and nipple size required for this type
of installation.
Step 1: Determine the cross-sectional area (square inches)
for
each conductor from Table 5 of Chapter 9 for insulated conductors and
Table 8 of Chapter 9 for bare conductors.
Step 2: Determine the total cross-sectional area for all
conductors.
Step 3: Size the raceway according to the percent fill as
listed in Table 1 of Chapter 9; 40% for three or more conductors and
60%
for raceways 24 in. or less in length (nipples).
Example 1: A 400A feeder is installed in Schedule 40 rigid
nonmetallic conduit. This raceway contains three 500 kcmil THHN
conductors, one 250 kcmil THHN conductor, and one 3 AWG THHN conductor.
What size raceway is required for these conductors?
Example 2: What size rigid metal nipple is required for three
3/0 AWG THHN conductors, one 1 AWG THHN conductor, and one 6 AWG THHN
conductor?
Visit EC&M's
Web site for the answers.
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Code Challenge
What's Wrong Here?
By Joe Tedesco
How does this
installation violate NEC requirements?
Hint: No, the cover from this panelboard wasn't removed prior
to taking this picture.
Code Q&A
By Mike Holt
Q. Is it permissible to install line and load
wiring in the same raceway?
See the answer.
Code Quiz
By Steven Owen
A 200A rated panelboard (load center) has wiring space
on each side that measures 4 inches wide by 4 inches deep. The total
length of the wiring space on each side is 36 inches. Three individual
splices that each consists of two 4/0 AWG THHN/THWN insulated
conductors
are connected by split-bolt connectors are located on one side of the
panelboard in the wiring space. Each split bolt connector is about
1.5625 square inches (2 cubic inches). Does the NEC permit these
splices
in the wiring space area of a panelboard? If they're permitted, do they
comply
with the NEC requirements for splices in enclosures?
- Yes, No
- Yes, Yes
- No, No
- No, Yes
Visit EC&M's Web
site
for the answer and explanation.
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Faces of the Code
Bob
Stoll Member, Code-Making Panel 5
For several years GFCIs and double-insulation design
have made it difficult to get shocked while using a power tool. "At
this
point in time, I don't think there's any situation where people will be
electrocuted unless they're standing in water or something like that,"
says Bob Stoll, technical director for the Power Tool Institute.
Despite
the already high level of safety, Stoll takes his work on CMP-5
seriously. No matter how safe power tools may be (an exception to
250.114 of the 2002 NEC nixes the requirement for a ground wire if
they're double-insulated), Stoll believes there's always room for
improvement. "Obviously, we can always improve safety," he says.
If it sounds like Stoll knows a thing or two about standards work,
it's because he has been there before. Prior to joining the Power Tool
Institute, he worked on UL standards for explosion-proof electrical
equipment in hazardous locations. And that experience has helped him
appreciate the format of the NEC process. "I like the fact that it's
open and that anyone can comment anywhere in the country," he says.
The lack of pressing electrical safety concerns has offered Stoll
some time to devote to other issues facing the power tool industry,
among them the increasing pressure to integrate power limiting features
in cordless power tools. Those in favor of the proposed legislation
that
would crack down on devices that use power for non-essential purposes
contend that the charging process for cordless tools continues to suck
up too much electricity even after the tool is fully charged, a claim
that Stoll disputes. "They say that we could save a couple nuclear
power
plants [by instituting the legislation]," he says. "But we think the
power saved by this is very minimal when you take into account the
number of tool changes that would be required."
Looking ahead, Stoll and the Power Tool Institute are keeping their
eyes on a device that has caused its fair share of controversy in the
electrical world: the AFCI. "We're seeing them in other types of
appliances, and we wonder it it's going to come into play for power
tools," he says. "We're interested in any kind of change to the Code
that could affect the power tool industry."
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Speak Out
Above and Beyond
Power tool safety has come so far over the years that
the Code no longer requires a ground wire for double-insulated tools,
seemingly putting the responsibility for safety on the manufacturer.
Should the NEC rely on manufacturers to make their products safe or err
on the side of caution by adding its own safety requirements? Visit EC&M's Web site to tell us.
At least when it comes to regulating low-voltage wiring licenses,
the
vast majority of CodeWatch readers believe less is more. More than
two-thirds of you said low-voltage installers shouldn't be required to
carry a license of any kind, begging the question, At what voltage
level
do you draw the line?
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current with important industry issues.
Shows and Events
EC&M Code
Conferences
Haven't signed up for one of EC&M's 2005 Code
Change Conferences yet? There's still time. Download
the registration form, and pick the closest seminar. Fill it out and
fax
it to (203) 929-5351. Registration for the first conference in Atlanta
on Oct. 27-28, is only open through this Friday, so act quickly. And if
you're planning on catching the Code caravan when it comes to
Philadelphia on Nov. 9-10, be sure to sign up by Sept. 10. Moderated by
Mike Holt and Fred Hartwell (Boston conference only), the two-day
conferences will cover everything you need to know about the 2005 Code.
All attendees will receive a copy of the 2005 NEC and EC&M's
2005
Code Change Book, written by Mike Holt.
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