Are primary protectors necessary?

Q: I am currently working on a project that requires cabling voice and data (Category 3 and Category 5) throughout some old public buildings. Some of these buildings have solid ceilings and solid walls, making cable runs difficult and perhaps unsightly. It has been proposed that, where practical, we run cable along outside walls in conduit and punch through into rooms where drops are required.

Q: I am currently working on a project that requires cabling voice and data (Category 3 and Category 5) throughout some old public buildings. Some of these buildings have solid ceilings and solid walls, making cable runs difficult and perhaps unsightly. It has been proposed that, where practical, we run cable along outside walls in conduit and punch through into rooms where drops are required.

My concern is that running cable outdoors requires that primary protectors be installed. Is this a legitimate concern, or would protectors not be necessary because this is not actually an interbuilding connection? I have checked the National Electrical Code (nec) but it doesn`t address this issue.

Paul Smith

ibm

Corpus Christi, TX

A: Sorry, but I just can`t resist: If running conduit on the inside of the building is unsightly, how can running conduit on the exterior of the building be any more aesthetically pleasing? Oh well. On to the technical issues...

You are correct in this scenario: nec 800-30 does not require installation of primary protectors. Have you ever noticed that all the cable parameters in tia/eia-568a are either specified at or corrected to 20oC? Ever wonder why? Because the authors have assumed that most data cabling is installed in air-conditioned space. So for this particular installation I suggest you do the temperature-correction calculations for both summer and winter months. These calculations will enable you to better approximate the times of day and months of the year that the Category 5 actually will be a 100-megahertz cabling system. This information should prove invaluable to the information-technology folks.

Donna Ballast is a communications analyst at The University of Texas at Austin and a bicsi reg-istered 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: ballast@utexas.edu

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