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This document provides the current carrying capacity or AMPACITY of coaxial cables usedin the Telecommunications industry. The method used to calculate the tabulated ampacitiesis a thermodynamic model of a cable installed indoors in air and considers the heat flow fromthe inner and outer conductor through the dielectric and jacket materials. It assumes that theconductors carrying current reach an operating temperature of 65C based on the cablesability to dissipate heat. This temperature was chosen to substantially minimize thepossibility of accelerated thermal aging of the dielectric and jacket materials. Systemdesigners are encouraged to consider the effect of this operating temperature on conductorresistance (R), voltage drop (IR) and power consumption (I2R).

The National Electric Code (NEC) considers the most convenient and expeditious method ofdefining the ampacity of cables to be through the use of tables. The tabular format includedin this document illustrates the ampacity of trunk, distribution and drop type coaxial cablescommonly used in the Telecommunications industry. This procedure shall not be used todetermine ground conductor size as referenced in the 1999 NEC, Article 820-40, (a)(3).

The ampacities provided for trunk and distribution coaxial cables are for copper-cladaluminum center conductors and solid (smooth wall) aluminum outer conductors. Dropcoaxial cable ampacities relate to cables with a copper-clad steel center conductor and acombination of aluminum tape(s) and braid(s), which represent the outer conductor.

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Published: 01/01/2001 ANSI: ANSI Approved Number of Pages: 8 File Size: 1 file , 89 KB