Cable require carbon/gas/electronic modules?

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bob99digi

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Ok, this may be a strange question, it may not make any sense, but here goes.

Anyone know of or heard of cable requiring carbon, gas and electronic modules on each pair of cable for building entrance protection?

This was mentioned at a meeting when discussing running a conduit with cable from the computer room in an existing building to the new computer room in a new building being constructed next to the existing building. The distance between buildings is roughly 200 feet. Cable ran underground will be in conduit. The cables enter the building in a garage used for storing vehicles which should be unclassified.

I've never heard of such a requirement and i've been looking through the 2005 NEC in article 500 for hazardous locations and article 800 and haven't found anything yet.

Thanks for any help.
 
bob99digi said:
Ok, this may be a strange question, it may not make any sense, but here goes.

Anyone know of or heard of cable requiring carbon, gas and electronic modules on each pair of cable for building entrance protection?

This was mentioned at a meeting when discussing running a conduit with cable from the computer room in an existing building to the new computer room in a new building being constructed next to the existing building. The distance between buildings is roughly 200 feet. Cable ran underground will be in conduit. The cables enter the building in a garage used for storing vehicles which should be unclassified.

I've never heard of such a requirement and i've been looking through the 2005 NEC in article 500 for hazardous locations and article 800 and haven't found anything yet.

Thanks for any help.
Click to expand...

You're talking "telephony".
 
This looks to me that this a requirement of SPD (Surge Protection Device) using a combination o f technologies and ibrid device that is the module and this are the definitions of the technologies.
Carbon block spark gap overvoltage suppressor — an older technology still found in telephone circuits. A carbon rod is held with an insulator a specific distance from a second carbon rod. The gap dimension determines the voltage at which a spark will jump between the two parts and short to ground. The typical spacing for telephone applications in North America is 0.003 inch (0.076 mm) Carbon block suppressors are similar to a gas arrestor but with the two electrodes exposed to the air.
Gas discharge tube (GDT) — These rely on a gas trapped between two electrodes that is ionized by the high voltage to conduct electrical current. GDTs can conduct more current for their size than other components. Like MOVs, GDTs have a finite life expectancy, and can take a few very large transients or a greater number of smaller transients. GDTs also take time to trigger permitting a higher voltage spike to exist before the GDT conducts significant current. It is not uncommon for a GDT to let through pulses of 500V or more of 100ns in duration. In some cases additional protection is necessary to prevent damage due to this effect. GDT create a short circuit when triggered, so that if any electric power (spike, signal, or power) is present, the GDT will short this, and will continue conducting until all electric current sufficiently diminishes. Unlike other protector devices, a GDT will conduct at a voltage less than the high voltage that ionized the gas. Gas arrestors are often used in telecommunication equipment. Due to an exceptionally low capacitance, GDTs are commonly used on high frequency lines
 
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