Q: I have a small Category 5 Ethernet local area network in a primary building and need to connect to a secondary building about 50 to 70 yards away. I have been told not to even think about a coaxial-cable run to the other buildings because of electric-shock problems. Yet, I have seen one operation where they ran Category 5 outside from one building to another building and have had no problems for years.
If not coaxial cable, why not Category 5, which seems to be no different from your local telephone company`s running its Category 3 outside? What is the best way to cable-connect these two buildings other than by dial-up on a semi-tight budget?
David Depew
Computer Consultants
Addison, TX
A: Follow a telephone service pro-vider`s outside-plant cable from the curb to the termination in the building, and you`ll find a listed primary protector. Follow a cable-TV service provider`s coaxial cable from the curb to the termination at the building, and you`ll likely find it directly connected to a television set or cable box. Why is this? The telephone cable is covered under National Electrical Code 800-30, but the cable-TV coaxial cable is not. There has been talk--but so far, just talk--in the industry of requiring protectors on cable-TV coaxial cable.
The best way to connect your two buildings is with fiber-optic cable and a transceiver at each end. If that brings costs over budget, a good second choice is Category 5 cable with a Category 5 protector at each end. Mindful that Category 5 is only a 100-megahertz system, if the channel is less than 100 meters long and the second building is 50 to 70 yards away from the first, you need to determine the overall cable length between the termination points.
Are you planning to connect the cable from the hub in building one to a hub in building two or just to connect directly to the workstation in building two? That will determine the number (size) of the cable(s) that you will need to install between the two buildings.
I have seen a lot of Category 5 cmr-rated cable buried in a shallow trench between buildings--usually between portable school buildings--without protectors at the ends. What they don`t realize is that in the event of lightning strikes or accidental contact with power conductors, the hub and workstations will be acting as the protectors. That protection lasts until water permeates the polyvinyl chloride jacket and shorts the conductors.
Category 5 cable is available with a polyethylene jacket, and Category 5 protectors are less expensive than hubs and workstations.
Donna Ballast is a communications analyst at The University of Texas at Austin and a bicsi registered communications distribution designer (rcdd). Questions can be sent to her at Cabling Installation & Maintenance or at PO Drawer 7580, The University of Texas, Austin, TX 78713; tel: (512) 471-0112, fax: (512) 471-8883, e-mail: [email protected]
