Listing requirements for low voltage power limited circuits and devices

[tilden]

I have an AC/DC power supply that's UL listed and outputs max 60W at 24VDC, so below the 100VA max to I believe be considered Class 2 (NEC 2023 Chap. 9 Table 11(B)). If I put this in an enclosure in a building, or outside, do the conductors I'm connecting this 24VDC output need to be "listed" (UL, ETL, etc) if I run them from the enclosure to another piece of equipment (sensors, cameras, etc)?

Same question for the powered devices - if a device outside of the enclosure is being fed by this 24VDC source, does it also need to be listed? My take on PoE is that at least the device would need to be listed per 725.160 since power and data are coming in on the same line, but if power is separate from data would it need to be?

 

[hbiss]

I have an AC/DC power supply that's UL listed and outputs max 60W at 24VDC, so below the 100VA max to I believe be considered Class 2 (NEC 2023 Chap. 9 Table 11(B)).

That's not your or my call. That table needs to be stricken. All we supposed to do is look at is the power supply and see what the label says. If it says Class 2 or Class 3 that's what it is. No marking, then it's automatically Class 1.

Loads or the powered devices are not marked, only the power supplies. However, I have seen some lighting fixtures for instance that have their 0-10 volt leads marked "Class 1 wiring only". That certainly makes it easier to provide wiring for it.

Class 2 or Class 3 requires CL2 or CL3 listed wiring. Class 1 requires a Chapter 1 wiring method.

My take on PoE is that at least the device would need to be listed per 725.160 since power and data are coming in on the same line, but if power is separate from data would it need to be?

POE has its own article, Article 840.

-Hal

 

[gene6]

There is lots and lots of non UL listed cable out-there for sale cheap, most is not even real copper.
If your working in a drop ceiling find out if its a also a return air shaft, apparently that's a big deal.
I worked on a job call where a dumpsters worth of regular PVC jacket cat6 cable was installed not according to its 'manufacturers listing' above a drop ceiling, then thru a 3 hour fire wall with a gaping hole left in said fire wall. We had to install what I think is a nylon jacketed 'plenum rated' cable in the drop ceiling.
We literally filled up a dumpster with brand new cable.