LV Track lighting

[I^2R]

Apologize if this was covered before, searched and couldn't find the answer.

Trying to lay out circuits for 12v track lighting in a restaurant. For high voltage track, we have always allowed 75W per foot per 220.43. This lets you run 25' per 20A circuit.

For the 12v track; Considering that 300W is the largest circuit, using the same logic, we could only run 4' of track per transformer? 25' per circuit at 120v seems reasonable, 4' does not. :-?

I'm pretty certain that I'm mis-applying 220.43 here.
We have had inspectors verify on a number of installs that we have circuited 120V track for 75VA per foot, so if this is the wrong way to apply this article, the inspectors are doing it too.

Any thoughts?

 

[Dennis Alwon]

I hear you. If you read the code it makes no mention of LV so I don't see why you would calculated it differently. Also if you look at the heading of the section (section III) it says feeder and service calculation. You are installing a branch circuit so, IMO, you are not bound by 220.43. Design of the circuit will keep you from overloading it.

 

[steve066]

Apologize if this was covered before, searched and couldn't find the answer.

Trying to lay out circuits for 12v track lighting in a restaurant. For high voltage track, we have always allowed 75W per foot per 220.43. This lets you run 25' per 20A circuit.

For the 12v track; Considering that 300W is the largest circuit, using the same logic, we could only run 4' of track per transformer? 25' per circuit at 120v seems reasonable, 4' does not. :-?

I'm pretty certain that I'm mis-applying 220.43 here.
We have had inspectors verify on a number of installs that we have circuited 120V track for 75VA per foot, so if this is the wrong way to apply this article, the inspectors are doing it too.

Any thoughts?

Two thoughts:

1. I don't have my code book in front of me, but I'm 95% sure 220.43 applies to feeder and service loads. That means you can run as much track as you want off a 20 A circuit. You only need to size the main service and any panel board feeders for 220.43. I think this is so additional branch circuits can be ran as necessary later, if someone adds more fixtures to a track.

So, 220.43 doesn't limit the length of line voltage track that can be placed on a branch circuit at all.

2. Since this doesn't limit the line voltage track you can place on one circuit, it doesn't limit the amount of track that can be placed on a low voltage transformer either.

Edit: I should of read Dennis's post closer, It looks like we both agree, and I'm just reapeating the same thing he said.

Steve