Run low voltage and AC wires through the same conduit?

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  #1  
Old 09-17-11, 07:43 PM
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Run low voltage and AC wires through the same conduit?

I have a conduit that runs from a box to the garage door opener. This conduit has in it both the AC wires for the door opener motor, as well as the low voltage wires for the open/close button.

I used #12 wires for all of them.

Is it OK to run them through the same conduit, as well as going in and out of some junction box that have other AC wires in them?

If it is OK, is there a standard way I can mark them as "low voltage"?
 
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  #2  
Old 09-17-11, 08:43 PM
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Generally no, low voltage circuits are almost always designed as "class 2" circuit and line voltage are always class 1 circuits. IF the low voltage is designed and constructed to class 1 standards then it is okay to have both in the same conduit but this is rarely the case and I can guarantee it is not the case with a residential garage door opener.
 
  #3  
Old 09-17-11, 11:30 PM
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They cannot be run in the same conduit, nor can they be in the same j-box with other AC wiring. However, the low-voltage wires can be run in a separate conduit to the same box as the AC at the garage door opener provided there is a separator in the box.
 
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Old 09-18-11, 07:28 PM
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I found this reference:

300.3(C) Conductors of Different Systems.
(1) 600 Volts, Nominal, or Less. Conductors of circuits rated 600 volts, nominal, or less, ac circuits, and dc circuits shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.

Exception: For solar photovoltaic systems in accordance with 690.4(B).

FPN: See 725.55(A) for Class 2 and Class 3 circuit conductors.
In either case, I have already ran a separate conduit for it so now I have two conduits running to the garage opener, one for the motor, one for the LV manual push button.

However, I am still trying to use the same box.

I have a double gang metal box that both conduits go into right at the entrance to the garage.

The conductors (one hot one neutral) for the motor just enters in one knock out and exits another one to another box two inches away.

The LV lines enter the box and there are two push button switches one for left door and one for right door.

I am hoping sharing a box this way is OK.
 
  #5  
Old 09-18-11, 07:41 PM
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I believe 725.55(A) discusses not allowing low voltage wiring to be with line voltage.

Typically, in practically all residential situations, low voltage can not be mixed in the same conduit or box.

They do sell boxes and dividers that allow them to be separated on different sides of a 2-gang (or larger) box. This is often used so one box can have 120v power and network or CATV in the same box and same plate - but there still has to be the plastic separation between the two.
 
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