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250.94
Grounding (Bonding) of Communications Systems
What's Wrong
Here?
Code Q&A
Code Quiz
NEC Report on
Comments Available Soon
EC&M Code
Change Conferences
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Top 50 NEC Rules
250.94
Grounding (Bonding) of Communications Systems
By Mike Holt
An accessible bonding point must be provided at service
equipment or the disconnecting means of separate buildings or
structures
for communications systems. The point can be any one of the
following:
- An exposed, nonflexible metallic raceway.
- An exposed grounding electrode conductor.
- An external connection approved by the authority having
jurisdiction.
FPN No. 2: Communications systems must be bonded together.
- Antennas / Satellite Dishes (810.21)
- CATV (820.100)
- Telephone Circuits (800.100)
The bonding of all external communications systems to a single point
minimizes the possibility of damage to the systems from potential
(voltage) difference between the systems.
Editor's note: This information was extracted from Mike
Holt's
textbook, Understanding
the National Electrical Code
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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: Full service door
Code Q&A
By Mike Holt
Q. I'm running a 4-wire lighting circuit with a
shared neutral. Can I use three single-pole breakers without handle
ties?
Visit EC&M's
Web site to see the answer.
Code Quiz
By Steven Owen
Q. Where a surge arrester is installed on a
circuit operating at less than 1,000V, it shall comply with all but
which of the following?
- The rating of the surge arrester shall be equal to or greater than
the maximum continuous phase-to-ground power frequency voltage
available
at the point of application.
- The surge arrester shall be identified for the application.
- Surge arresters shall be marked with short-circuit current rating
and shall not be installed at a point on the system where the available
fault current is in excess of that rating.
- Surge arresters shall not be installed on ungrounded systems,
impedance grounded systems, or corner grounded delta systems unless
listed specifically for use on these systems.
Visit EC&M's
Web site for the answer and explanation.
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Code News Update
NEC Report on Comments
Available Soon
The 2007 NEC Annual Revision Cycle Report on
Comments will be made available a week from this Friday, on March
23. You can download the file from the NFPA
Web site.
See something in the report you're not too happy with? You can
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