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Communications Systems - Understanding NEC Requirements
 

 

Topic - NEC
Subject - Communications Systems - Understanding NEC Requirements

June 26, 2009
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Understanding NEC Requirements of Communications Systems

 

Image1Chapter 8 of the National Electrical Code covers the wiring requirements for communications systems such as telephones, radio and TV antennas, satellite dishes, closed-circuit television and cable TV systems, as well as network-powered broadband communications systems not under the exclusive control of the communications utility.

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This Chapter is an excerpt from Mike Holt’s Illustrated Guide to Understanding the NEC, Volume 2 Articles 500-820.
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Comments
  • From my textbook.

    410.30 Supports. (A) General Support Requirements. Luminaires and lampholders must be securely supported. (B) Metallic or Nonmetallic Poles. Metallic or nonmetallic poles can be used to support luminaires, and they can be used as a raceway.

    Author’s Comment: With security being a high priority, many owners want to install security cameras on existing parking lot poles. However, 820.133(A)(1)(b) prohibits the mixing of power and communications conductors in the same raceway. Figure 410-30B0 01

    In addition, they must comply with the requirements of (1) through (6). (1) The pole must have an accessible 2 in. x 4 in. handhole with a cover suitable for use in wet locations that provides access to the supply conductors within the pole. Ex 1: The handhole isn’t required for a pole that’s 8 ft or less in height, if the supply conductors for the luminaire are accessible by removing the luminaire. Figure 410-30B1x1 01 Ex 2: The handhole can be omitted on poles that are 20 ft or less in height, if the pole is provided with a hinged base. (2) When the supply raceway or cable doesn’t enter the pole, a threaded fitting or nipple must be welded, brazed, or attached to the pole opposite the handhole opening for the supply conductors. (3) A metal pole must have an equipment grounding terminal accessible from the handhole. Ex: A grounding terminal isn’t required in a pole that’s 8 ft or less in height above grade if the splices are accessible by removing the luminaire. (5) Metal poles used for the support of luminaires must be connected to an equipment grounding conductor of a type recognized in 250.118 [250.4(A)(5)]. Figure 410-30B5 01

    DANGER: Because the contact resistance of an electrode to the earth is so high, very little fault current returns to the power supply if the earth is the only fault current return path. Result—the circuit overcurrent device won’t open and clear the ground fault, and the metal pole will become and remain energized by the circuit voltage. Figure 250-04A5 04

    (6) Conductors in vertical metal poles must be supported when the vertical rise exceeds 100 ft [Table 300.19(A)].

    Author’s Comment: When provided by the manufacturer of roadway lighting poles, so-called J-hooks must be used to support conductors, as they’re part of the listing instructions [110.3(B)].



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