# NEC 680.23(A)(8), low-voltage contact limit



## Dennis Alwon (May 9, 2009)

There is no mention of a current limiter however the transformer that are listed for pools have a separation between primary and secondary so that there can be no increase in voltage ( an isolation transformer )


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## Dennis Alwon (May 9, 2009)

There is a good read from a UL member and cmp member Mark Odie on low voltage landscape lights and pools--I know that it is not exactly what you want but it may be worth the read. Here is the link-- the article is a bit dated 2004

http://site.ul.com/global/documents/offerings/perspectives/regulators/LVLighting.pdf


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## jm0le (Sep 5, 2014)

Dennis Alwon said:


> There is no mention of a current limiter however the transformer that are listed for pools have a separation between primary and secondary so that there can be no increase in voltage ( an isolation transformer )


We'll be using switching power supplies (thank goodness the latest codes finally have language referring to power supplies, instead of just transformers), which will be listed for pool/spa usage.

I'll check out the article you posted as well.


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## jm0le (Sep 5, 2014)

Ah, from the article, it says: "The power supply can provide multiple secondary circuits but each secondary circuit can only be 25 amps with a maximum of 300 watts."

Not sure if this applies to underwater luminaire supplies as well, but 300 watts is definitely enough to work with. 

It seems like the Class 2 limitations (100VA) only apply for cable runs in walls, floors, and ceilings; or other places where "chapter 3 wiring methods are not easily installed". 

Guess I'll find out for sure when the UL/Intertek folks get back to me.


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## Dennis Alwon (May 9, 2009)

300 watts has always been the limitation on low voltage transformers. You can get a 600 watt trany or a 900 watt trany but it is basically 2 or 3 300 watt transformers in one. You would have 2 or 3 sets of leads coming off different transformers.


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## wildleg (Apr 12, 2009)

the class 2 and class 3 power limitations are listed in table 11a and 11b in the back of the codebook


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## jm0le (Sep 5, 2014)

wildleg said:


> the class 2 and class 3 power limitations are listed in table 11a and 11b in the back of the codebook


Thanks, will reference it.

The only question that remains is if class 3 is applicable for a "listed low-voltage lighting system not requiring grounding". My guess is that this is a question that will only be answered by the relevant UL Standard (UL 676), rather than the NEC.


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## Dennis Alwon (May 9, 2009)

wildleg said:


> the class 2 and class 3 power limitations are listed in table 11a and 11b in the back of the codebook


Thanks I never noticed those tables. These tables are in Chapter 9 if anyone is looking for them


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