By Mike Holt
Chapter 8, while important, has only
four Articles:
- Article 800: Communications circuits.
The focus is on wiring.
- Article 810: Radio and television
equipment. The focus is on antenna circuits.
- Article 820: Community antenna
television and radio distribution systems. The focus is on coaxial cable circuits.
- Article 830: Network-powered broadband
communications systems. The focus is on systems that use power from the network.
We will look at each of these in turn.
You will notice the primary themes are cable protection and proper grounding.
Article 800. Communication Circuits
This Article has its roots in POTS (Plain
Old Telephone System). Consequently, it addresses telephone wiring and similar or related
systems that use twisted-pair wiring. Here are some key points to remember about Article
800:
- Do not attach incoming cables to
the service entrance power mast.
- It is critical to determine the
"point of entrance" for these circuits.
- You must ground the primary protector
as close as practicable to the point of entrance.
- Keep in mind that the purpose of
grounding is to provide unwanted current a way to get back to the source. This purpose
dictates several other requirements, such as keeping the primary protector grounding
conductor straight and as short as possible.
- If you locate cables above a suspended
ceiling, route and support them to allow access via panel removal.
- Keep these cables separated from
lightning-protection circuits.
- If you install cables in a Chapter
3 raceway, you must do so in conformance with the BICSI Cabling Installation Manual.
- Special labeling and marking provisions
apply-follow them carefully.
Article 810. Radio and Television
Equipment
This Article has its roots in wireless
communications. Consequently, it addresses transmitter and receiver equipment-and the
wiring and cabling that is part of the systems that equipment serves. Here are some key
points to remember about Article 800:
- Avoid contact with conductors of
other systems. In our study, we'll explain what this means and why it is so important.
- Do not attach antennas or other
equipment to the service entrance power mast.
- If you don't ground the mast properly,
you risk total destruction of the mast by voltage surges caused by nearby lightning
strikes.
- Keep in mind that the purpose of
grounding is to provide unwanted current a way to get back to the source. This purpose
dictates several other requirements, such as keeping the grounding conductor straight
and protecting it from physical damage.
- If you don't bond the mast properly,
you risk flashovers and possible electrocution.
- Keep in mind that the purpose of
bonding is to prevent a difference of potential between metallic objects or other
conductive items, such as swimming pools. Thus,
- Article 810 provides several different
bonding requirements.
- Clearances are critical. Article
810 provides extensive clearance requirements. For example, it provides separate clearance
requirements for indoors and outdoors.
Article 820. Community Antenna Television
and Radio Distribution Systems
This Article focuses on the distribution
of television and radio signals within a facility or a property via cable, rather than
their transmission or reception via antenna. These signals are limited-energy, but they
are high-frequency.
- As with Article 800, you must determine
the "point of entrance" for these circuits.
- You must ground the incoming cable
as close as practicable to the point of entrance.
- If you locate cables above a suspended
ceiling, route and support them to allow access via panel removal.
- Clearances are critical. Article
820 provides extensive clearance requirements. For example, Article 820 requires at
least 6 feet of clearance between coaxial cable and lightning conductors.
- If you use a separate grounding
electrode, you must run a bonding jumper to the power grounding system.
Article 830 Network-Powered Broadband
Communications Systems
An introduction does not make sense,
here. - Mark L.
Understanding
the NEC, Volume 2 Workbook 2002 |
 |
Understanding
the National Electrical Code - Volume 2, 2002 Edition was written
to provide insite into and an understanding of, many of the technical
rules of the NEC. This book covers Articles 500-830. Subjects include:
Hazardous (Classified) Locations, Motor Fuel Dispensing Facilities,
Health Care Facilities, Manufactured Wiring Systems, Swimming Pools,
Fountains and Similar Installations, Emergency Systems, Optical Fiber
Cables and Raceways and more.
Product Code:
02UNWB2

|
|
|
|