| CONTENTS
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700.9 Wiring for
Emergency Power Systems
What's
Wrong
Here?
Code Q&A
Code Quiz
Electric
West 2009
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Top 2008 Code Changes
700.9 Wiring for Emergency Power
Systems
By Mike Holt
The rules on "emergency circuits independent of all
other wiring" when a single generator supplies emergency, legally
required, and/or optional loads were further clarified in the 2008 NEC.
(B) Wiring. To ensure that a fault on the normal wiring
circuits will not affect the performance of emergency wiring or
equipment, all wiring to emergency loads shall be kept entirely
independent of all other wiring, except:
- Wiring in transfer equipment.
- Luminaires supplied from two sources of power.
- Junction box attached to luminaires supplied from two sources of
power.
- Wiring within a common junction box attached to unit equipment,
containing only the branch circuit supplying the unit equipment and the
emergency circuit supplied by the unit equipment.
- Wiring from an emergency source is permitted to supply any
combination of emergency, legally required, or optional loads in
accordance with the following:
(a) From separate vertical switchboard sections or from individual
disconnects mounted in separate enclosures.
(b) By single or multiple feeders without overcurrent protection at the
source.
(c) Legally required and optional standby circuits shall not originate
from the same vertical switchboard section, panelboard enclosure, or
disconnect as emergency circuits.
A new subsection (5) was added to clarify that separation of the
circuits
served by a generator source for emergency, legally required, and
optional circuits may be accomplished by running feeders from a single
generator to individual overcurrent protective devices or to a
distribution switchboard that separates emergency circuits in different
vertical sections from other loads.
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Code Challenge
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: Fender bender
Code Q&A
By Mike Holt
Q. What are the NEC lighting and switching
requirements for stairways?
Visit EC&M's Web
site to see the answer.
Code Quiz
By Steven Owen
When installing coaxial cables beyond the point of
grounding, when is it permissible to support coaxial cables by means of
attachment to a conduit or other raceway?
- In a commercial garage (oil change) pit where a camera is
installed,
and only experienced technicians work in the pit.
- In any commercial location where public access is restricted, and
only experienced technicians work in these areas.
- Only where it is necessary to support coaxial cables because no
other method of support is readily available.
- Excluding exception(s), it is not permitted per Art. 820
installation requirements.
Visit EC&M's
Web site for the answer and explanation.
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Shows and Events
Electric West
2009
The Electric West Show, to be held March 18-20, 2009 at
the Las Vegas Convention Center in conjunction with the Power Quality
Reliability Conference, is the perfect place to brush up on the latest
NEC topics – and earn continuing education credits in the process.
Geared toward electrical contractors, consulting & specifying
engineers,
electricians, and plant facility personnel, there’s something for
everyone at the Electric Show. The biggest electrical marketplace in
the
western United States, this event attracts 250 exhibiting companies and
more than 6,000 attendees every year. Here's a preview of some of the
NEC seminars planned for next year's event:
- One- and Two-Family Dwelling Unit Electrical Systems
- Changes to the 2008 NEC
- Swimming Pools and Similar Installations (NEC Article 680)
- Introduction to the 2009 NFPA 70E
For more information, visit our Web
site.
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Database.
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