Article 800 - Communications Systems

By Mike Holt, for EC&M Magazine

Article 800 - Communications Systems

800.40(A)

The grounding electrode conductor for the metallic member of communications cable sheath shall be _____.

(a) insulate     (b) copper      (c) not smaller than 14 AWG            (d) all of these

Answer: (d) all of these. Where communications cables enter buildings, they shall be grounded as close as practicable to the point of entrance or shall be interrupted as close to the point of entrance as practicable [800.33]. Where grounded the grounding conductor shall be insulated, copper and not smaller than 14 AWG.

800.50 Exception No. 3

Communications cables installed within buildings shall be listed as being suitable for the purpose. However, cables are not required to be listed if the length of the cable within the building does not exceed _____ ft.

(a) 5    (b) 25  (c) 50  (d) 100

Answer: (c) 50 ft. The general rule is that communications cables within a building shall be listed, but Exception No.3 to 800.50 permits unlisted cable to enter the building for a distance of 50 ft.

Article 810 Receiving Equipment

810.21(E)

Masts and metal structures supporting antennas as well as each conductor of a lead-in from an outdoor antenna shall be grounded. The grounding conductor used for this purpose shall be run in as straight a line as practicable from the mast or discharge unit to the grounding electrode.

(a) True           (b) False

Answer: (a) True. Section 810.15 requires the masts and metal structures supporting antennas to be grounded, 810.20 requires a each conductor of a lead-in from an outdoor antenna shall be provided with a listed antenna discharge unit, and 810.20(C) specifies that the antenna discharge unit shall be grounded in accordance with 810.21. Section 810.21(E) specifies that the grounding conductor for the antenna mast and/or antenna discharge unit to be run in as straight a line as practicable from the mast or discharge unit to the grounding electrode. Failure to run this conductor in accordance to the NEC can actually route the energy from lightning into the structure.

Article 820 – CATV

820.11(B)

Underground coaxial cables shall be separated at least 300 mm (12 in.) from light or power conductors, even if the light or power conductors are installed in a raceway or nonmetallic cable, such as UF or USE cable.

(a) True           (b) False

Answer: (b) False. The 12 in. rule does not apply if the light or power conductors are installed in a raceway or nonmetallic raceway, or if the coaxial cables are in a raceway.

Mike’s Comment: If you have any feedback, please let me know

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