Low Voltage Lighting (long)

[ryan_618]

As many of you know, I have been intrigued (obsessed) with trying to figure out the code requirements for low voltage lighting. In particular, the wiring methods. My thoughts have been that the low voltage cables commonly installed are not permitted anywhere, because Chapter 3 doesn't count them as a wiring method. 90.3 says that all chapter 3 rules apply to a chapter 4 installation.

Before I describe what I am thinking, I am going to paste the 2008 text of the relevent sections of Article 411:

411.3 Listing Required. Lighting systems operating at 30 volts or less shall comply with 411.3(A) or 411.3(B).
(A) Listed System. Lighting systems operating at 30 volts or less shall be listed as a complete system. The luminaires, power supply and luminaire fittings (including the exposed bare conductors) of an exposed bare conductor lighting system shall be listed for the use as part of the same identified lighting system.
(B) Assembly of Listed Parts. A lighting system assembled from the following listed parts shall be permitted.
(1) Low voltage luminaires
(2) Low voltage luminaire power supply
(3) Class 2 power supply
(4) Low voltage luminaire fittings
(5) Cord (secondary circuit) that the luminaires and power supply are listed for use with
(6) Cable, conductors in conduit, or other fixed wiring method for the secondary circuit
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.

411.4 Specific Location Requirements
(A) Walls, Floors, and Ceilings. Conductors concealed or extended through a wall, floor, or ceiling shall be in accor?dance with (1) or (2):
(1) Installed using any of the wiring methods specified in Chapter 3
(2) Installed using wiring supplied by a listed Class 2 power source and installed in accordance with 725.130.

411.5 Secondary Circuits.
(D) Insulated Conductors. Exposed insulated secondary circuit conductors shall be of the type and installed as, described in (1), (2), or (3).
(1) Class 2 cable supplied by a Class 2 power source and installed in accordance with Parts I and III of Article 725.
(2) Conductors, cord or cable of the listed system and in?stalled not less than 2.1 m (7 ft) above the finished floor unless the system is specifically listed for a lower in?stallation height.
(3) Wiring methods described in Chapter 3.

Here is what I am thinking, and I am quite interested in hearing what you guys think.

A low voltage lighting system is a piece of equipment (chapter four is equipment for general use). With that said, the transformer, the cable and the luminaire is a single piece of equipment--a low voltage lighting system. With that said, the branch circuit ends at the primary conductors feeding the transformer...everything downstream of that is a piece of equipment. The outlet is the end of the cable feeding the transformer.

The branch circuit is wired with a chapter three wiring method, as required in 300.3, up to the outlet (the end of the primary circuit). After that, Chapter 3 ends and chapter 4 begins. Once the branch circuit ends, the equipment is simply installed in accordance with the applicable Article in chapter 4, and the listing requirements.

411.4(A)(1) specifies that the low voltage cable (part of the equipment) must be in a chapter three wiring method if concealed. I submit that you can install the cable in EMT, ENT or any other chapter three wiring method...after all, the wiring method is the conduit, not the conductors (or cable) inside of it.

New section 411.5(D) is intersesting. It will now require the low voltage cable to be in a chapter three wiring method, unless it is 7 feet above the floor.

 

[Pierre C Belarge]

Ryan
I also am very interested in this topic.

My first question to you is why have you not mentioned the 411.4 portion that is related to 725 wiring methods?

or

Are we tackling the other requirements first?

BTW: 411.5(D) is new to me and I will need some time to digest this.
Have you spoken to Mark Ode about this yet (he also is interested in this topic, and I know you two are friends)?

 

[peteo]

Thank you for posting this. It 'looks' significantly rewritten, and leaves me with a question. The much more prescriptive later language specifies,

as part of the same identified lighting system.

Am I the only one who didn't understand that the previous language permitted any mixture of low voltage transformer, cabling, and luminaire to be assembled into a system? The new language appears to address this specifically. Have I missed something in my reading or use of the language?