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What's Wrong Here?

Oct 22, 2009 11:16 PM, By Brian J. McPartland, NEC Consultant

This photo shows an application where both CATV coaxial cable and conductors for power and light are run in a common raceway and box. This is clear violation of the rule given in 820.133(A), "Separation from Other Conductors."

In part (A)(1)(b), the Code says that "Coaxial cable shall not be placed in any raceway, compartment, outlet box, junction box, or other enclosure with conductors of electric light, power, Class 1, non-power-limited fire alarm, or medium-power network-powered broadband communications circuits." There are two exceptions to this rule.

The first exception recognizes the use of CATV cables within a common raceway and/or box where a "permanent barrier or listed divider" is used to effectively separate the power conductors from the CATV coaxial cable. As can be seen, such is not the case here.

The second exception recognizes limited introduction of power circuits within common "outlet boxes, junction boxes, and similar fittings or compartments where such conductors (power conductors) are introduced solely for power supply to the coaxial cable distribution system. The power circuit conductors shall be routed with the enclosure to maintain a minimum 6-mm (0.25-in) separation from coaxial cables."

Although the rules of 300.3(C) cover general requirements for segregation of conductors from systems operating at different line voltages, the individual rules given in Chapter 8 on the various types of communication circuits more completely specify permissions and limitations for co-mingling of such conductors within raceways and enclosures that also enclose power and light circuits. Also, the rules for co-mingling of power and light conductors with other types of low-voltage systems (e.g., Art. 725: Class 1, Class 2, and Class 3 Remote Control, Signaling, and Power-Limited Circuits are given in Chapter 7.)

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