National Electrical Code Tips: Article 800, Communications Circuits, Part 2
- The requirements for communication system wires and cables outside and entering buildings are in Article 800, Part II. They are, as you would expect, different for aerial versus undergound.
- If the wires and/or cables are on poles and in-span, four rules apply:
1. Locate them below the electric light and/or power conductors, if practicable.
2. Don't attach them to a cross-arm that carries light and/or power wires.
3. Provide climbing space per 225.14(D).
4. Observe the clearance requirements of 800.44(A)(4).
- Where practical, the communication system wires and cables on poles should be located below the electric light and power conductors [800.44(A)(1)].
- Communications wires and cables cannot be attached to crossarms that carryt electric light or power conductors [800.44(A)(2)].
- The climbing space through wires and cables must comply with 225.14(D) [800.44(A)(3)].
- If the wires and/or cables are above roofs, the vertial clearance must be at least 8 ft from all points of roofs above which they pass [800.44(B)]. Three exceptions exist.
- Overhead communications cables can be attached to an above the roof raceway mast (but not to the raceway itself) that does not enclose or support the conductors of electric light or power [800.44(C)].
- What if the communications cables extend between buildings? In that case, they and their supports must be identified as being sufficient to support the load to which they might be subjected [800.44(D)]. An exception to this rule applies to coaxial cable and involves an additional requirement for a messenger cable.
- If you use metallic conduit for communications entrance wire or cable, it must be bonded to the grounding system [800.49]. This requirement is stated incorrectly, it should apply to metal raceway of all types not just conduit.
- Where possible separate communications wires and cables from lightning conductors by at least 6 ft. [800.53]. The idea of "possible" includes routing them way out of the way instead of taking the shortest route right past the down conductors. Remember, the lightning conductors basically cannot be relocated and must have the gentlest bends possible with the straightest possible path from the roof to the ground. Communications cables give you a lot more leeway here, take it if you need to.