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It is my understanding that low-voltage wires can share a double-gang box with 120V wires, as long as they are isolated from each other by a permanent divider. I was looking at getting this relay to operate an inline duct booster fan using the 24V thermostat signal wire. However both the low-voltage and the 120V wires would come into the box bundled together through the same knockout. Is there an exception for relays, or something that I am missing? Or can I just punch a hole in a divider and snake the low-voltage wire through and just keep the splices separate? This is in the United States in a state on 2017 NEC if it makes a difference

User41943
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    You may note the lack of a UL device marking or a RU (the R would be backwards) registered component mark on that device... – Ecnerwal May 31 '23 at 18:25
  • The picture doesn't show the UL logo but the [manufacturer's datasheet](https://www.functionaldevices.com/wp-content/uploads/2021/08/RIB2401B.pdf) says that it is UL listed for both US and Canada – User41943 May 31 '23 at 19:16
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    @ecnerwal RiB is UL listed. Amazon is not a reliable supplier though, OP, if you were wondering why the mistrust. – Harper - Reinstate Monica May 31 '23 at 19:27
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    Note the ones from this manufacturer that provide the desired separation and the ones that do not are all UL listed for their respective applications. It's up to you to use them correctly. – jay613 May 31 '23 at 20:26
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    I suggest you contact your inspector at the building department. I had a similar problem many years ago and I did not have to put in a barrier or anything, the only requirement they had was the insulation on the low voltage side had to equal or exceed the rating on the line side. I used 1000 volt rated wire and it passed without any problems. Sometimes they are on your side. My panels ranged from 1 relay to 24 relays. – Gil May 31 '23 at 21:40
  • @Gil they let you exit the LV wires to the outside through a knockout? That's what OP needs to do. And more .... OP will then connect those wires to other signal equipment that includes wires that are NOT appropriately rated. – jay613 May 31 '23 at 21:53
  • I used a romex type clamp for the LV wires and the mains wiring but they were in different connectors to the same box. All of my LV wiring was at that rating. The LEDs etc I could not do anything about. I used what I called "shunt LEDs" which were the indicator leds shunted with a SMD resistor about 30 Ohm in series with the relays which drew about 55mA. The power supply put out about 28V which worked just great with the 24V relays. – Gil May 31 '23 at 22:12
  • It looks like that relay has a split coil that can be operated on *either* 24 volts or 120 volts. If it's operated on 120 volts the wires can be bundled, but if it's operated on 24 volts they shouldn't be bundled; they should be separated. Clearly they can't be both bundled and separated, thus the dilemma here. – Steve Summit Jun 01 '23 at 15:45
  • If it was me, I would decide whether I wanted to switch my relay with high voltage or low voltage, and if I wanted low voltage, I would choose a relay that had a single-voltage coil, and separated wires. (There are lots that are built that way, because it's obviously a common need.) Just Say No to this weird, unnecessarily general item. – Steve Summit Jun 01 '23 at 15:45

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You're on the right track. The same manufacturer (and others) make similar relays where the low and high voltage wires come out opposite sides of the device, with either the high voltage or low voltage ones coming through the knockout, so you just buy the appropriate one depending on whether you want the relay inside or outside the junction box.

jay613
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