Class 2, 12V Circuit

[Shujinko]

I don't work much with class 2 circuits but from my interpretation of the NEC, per Chapter 9 Table 11(B), if I have a 12V class 2 circuit, the largest transformer or power supply I can use to feed this circuit is 60VA? This is based on the "0-20V(max)" column and "Power Source Max Nameplate Rating" row of Table 11(B). Please advise if I am interpreting this correctly?

This is for some LED light panels on a 120V circuit but they get stepped down to 12V. If 60VA is the limit on the power supplies I can use, there will be a lot of power supplies in the ceiling. Thanks for reading me.

 

[augie47]

411.3(A) might cause you a problem.

 

[iwire]

I don't work much with class 2 circuits but from my interpretation of the NEC, per Chapter 9 Table 11(B), if I have a 12V class 2 circuit, the largest transformer or power supply I can use to feed this circuit is 60VA? This is based on the "0-20V(max)" column and "Power Source Max Nameplate Rating" row of Table 11(B). Please advise if I am interpreting this correctly?

This is for some LED light panels on a 120V circuit but they get stepped down to 12V. If 60VA is the limit on the power supplies I can use, there will be a lot of power supplies in the ceiling. Thanks for reading me.

A class 2 power supply will say class 2.

As far as low voltage lighting systems please take a few minutes and read article 411. There are a lot of rules regarding listings and sizes of equipment and wire types.

 

[Shujinko]

So I thought I was good based on 411.3(B) Assembly of Listed Parts. But I think the very last paragraph might snag me as there will be some exposed 12V conductors from the LED light panels to the power supply in my installation. Which means I will need a complete listed system similar to that described in 411.3(A).

The last paragraph in 411.3(B) reads, "The luminaires, power supply, and luminaire fittings (including the exposed bare conductors) of an exposed bare conductor lighting system shall be listed for use as part of the same identified lighting system".

Your thoughts? I guess the only solution would be to put those conductors in conduit and then I would still comply with 411.3(B).

 

[Shujinko]

Let me re-phase something from my last post the 12V conductors between the LED light panels and the Power supply will be insulated conductors, not bare conductors.

 

[kwired]

According to 411.4 your components including the cord/cable all need to be listed as a system. If you use the listed components in accordance with their instructions it should be a little hard to violate anything in 411.

 

[GrayHair]

411.6(D) seems to allow appropriately listed "non-system" insulated conductors.

 

[Shujinko]

Thanks for all the responses. However, I would still like to know if I'm interpreting NEC Chapter 9 Table 11(B) correctly, for a 12V, class 2 circuit is the largest power supply or transformer I can use 60VA?

 

[GoldDigger]

Thanks for all the responses. However, I would still like to know if I'm interpreting NEC Chapter 9 Table 11(B) correctly, for a 12V, class 2 circuit is the largest power supply or transformer I can use 60VA?

That is how I interpret it, as long as the power supply or transformer is current limiting. That 60VA is the nameplate power of the Class 2 supply.
If external OCPD is used the power source can be larger, but you cannot actually use the extra power.