What’s Wrong Here? Hint: Feel the Power

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The blue and white wires in Photo 1 (above) are the 120V branch circuit wires feeding power to this fire alarm panel. The red cables are power-limited fire alarm circuit cables. According to 760.136(A), "Power-limited fire alarm circuit cables and conductors shall not be placed in any cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar fitting with conductors of electric light, power, Class 1, non–power-limited fire alarm circuits, and medium-power network-powered broadband communications circuits unless permitted by 760.136(B) through (G)." According to 760.136(B) and (C), methods to permit both types of circuits in the same enclosure include keeping them separated by a barrier or by installing a raceway within the enclosure to keep the two types of circuits from contacting each other.

Photo 2 (above) clearly shows that there is no separation between the two types of circuits. The blue and white power wires are actually in contact with the fire alarm circuit conductors. This is a violation of Sec. 760.133(D). The power-limited conductors are permitted in the same enclosure with the power conductors, because both sets of conductors connect to the same fire alarm equipment; however there should be at least ¼ in. separation from the conductors and cables of power-limited fire alarm circuits and the branch circuit power wires.

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