Table 300.5 Column 5

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I am aware of NEC 90.3 Code Arrangement and thus why I was pushing for column 5 of 300.5. However, I have to admit I never took 725.3 to say disregard anything in 300 and only obey (A)-(G), I have now been persuaded :). I guess I need to take it more globally then I have in the past. I do think I see a small addition to the general rule in 725.46 for Class 1 circuits which says you shall comply with Part I of article 300. However, you might argue that exception 2 gets you out of it because of 725.3 again? I also don?t understand the purpose of column 5 as it is describing a class 2 or 3 circuit. Finally, I am still seeing a 300VA landscape transformer with a 25A 12V AC breaker saying you can put LV cable at 0-6?. As far as I can tell that would make it a class 1 power-limited circuit at best and thus 725.46 kicks in (I think).
 
I think I finally got the answer. I called up a couple of the landscape transformer companies and they give me the following logic:
If the Transformer is UL 1838 (which is Lighting transformers for 12V 25A) then clause 51.1 (Installation Instructions) says the following: Installation instructions shall be provided with the power unit that include specific instructions for mounting, proper wiring, ground, and servicing. The instructions shall inform the installer that the main secondary wiring is intended for shallow burial-less than 6 inches- unless the manufacture has provided wiring intended for direct burial.Then there is clause 53.3 (Main secondary wiring) Main secondary wiring shall consist of SPT-3, SPT-2 W, underground low energy circuit cable, or wire that is intended for wet locations, is sunlight resistand, and is intended for direct burial as defined in UL 493.Then they referred me to NEC 110.3(B) which says the transformer must be installed according to the manufacture instructions.

It was important to note that a UL-508 transformer does not give the low burial listing and would have to follow NEC table 300.5 column 5 of 6 inches min.

I believe this is the true answer that I was looking for. I find it amazing that an engineer has to get this exeption from a clause in a UL test to allow the higher burial depth. I seems to me it should be found in a special section of NEC 411.
 
I believe that something was missed here by the previous posters.


Lets start with Table 300.5, Column 5.

We see the specific requirements for landscape lighting.


411.4 Specific Location Requirements.

(A) Walls, Floors, and Ceilings.
Conductors condealed or extended through a wall, floor, or ceiling shall be in accordance with (1) or (2):



411.4(A) is for specific locations, of which landscape lighting locations are not mentioned. ----see wall, floor, and ceiling

Therefore, we follow the requirements of Table 300.5, Column 5.

Note:
Also, remember that most landscape lighting is not supplied via Class 2 or Class 3 type supplies/transformers.
 
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