Separating Class 2 circuit from electric power circuit

Coppersmith

Senior Member
I'm a little unclear concerning 725.136.

I have two class 2 circuits, five electric power circuits, a class 2 transformer, and two relays in an enclosure. The class 2 circuits are controlling the electric power circuits through the relays. The transformer is powering the class 2 circuits.

Am I correct in saying I don't have to a barrier between the class 2 circuits and the power circuits per (B) since these circuits are associated? (D)(1) says they only have to be separated by 1/4" (free air I assume). It wasn't clear if both applied.

Bonus question: I'm using RIB relays. The class 2 and power circuits all emerge from one 1/2" nipple. I can separate them quickly but they come closer than 1/4" as they enter the box. 725.136(E) says this is OK as long as there is tubing separating them, but there is not. Is this a problem?


725.136 Separation from Electric Light, Power, Class 1,
Non–Power-Limited Fire Alarm Circuit Conductors,
and Medium-Power Network-Powered Broadband
Communications Cables.

(A) General. Cables and conductors of Class 2 and Class 3
circuits 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 725.136(B) through (I).

(B) Separated by Barriers. Class 2 and Class 3 circuits
shall be permitted to be installed together with the conductors
of electric light, power, Class 1, non–power-limited fire
alarm and medium power network-powered broadband communications
circuits where they are separated by a barrier.

(D) Associated Systems Within Enclosures. Class 2 and
Class 3 circuit conductors in compartments, enclosures, device
boxes, outlet boxes, or similar fittings shall be permitted
to be installed with electric light, power, Class 1, non–
power-limited fire alarm, and medium-power network powered
broadband communications circuits where they
are introduced solely to connect the equipment connected
to Class 2 and Class 3 circuits, and where (1) or (2) applies:

(1) The electric light, power, Class 1, non–power-limited fire
alarm, and medium-power network-powered broadband
communications circuit conductors are routed to maintain
a minimum of 6 mm (0.25 in.) separation from the conductors
and cables of Class 2 and Class 3 circuits.
 

don_resqcapt19

Moderator
Staff member
The 1/4" separation applies within the enclosure, and there is no need for a barrier. The NEC does not really address the construction of manufactured products. Assuming that it is listed for the purpose it is fine.
 

GerryB

Senior Member
0-10 VOLT DIMMING

0-10 VOLT DIMMING

I have a similar question. Can you bring a CLP-3 conductor into a 277 volt switch to feed. The switch has power leads and the dimming leads on it, so how do you separate .25 inch. The MC luminaire cable is listed for this, but if you don't use that cable how should it be done. Art 725.48(A) and 725.49(B) seem to say the insulation needs to be rated for 600 volts.
 
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