Help understanding flexible cords/fixture wires for LED luminaires

[EK001]

Hello,

I have been reading NEC 2017 Sections 400, 402 and 410 trying to understand the requirements for LED luminaires when connected with flexible cords and could use some help.

The questions below are all relating to LED luminaries powered via flexible cords.

1. If a flexible cord is used for wiring, does the luminaire have to come with a built in male connector so that a flexible cord with a corresponding female connector can plug in during final installation (410.62 (C)(1)(a))? Need to ensure I am understanding this clause correctly.

2. Is it acceptable for the flexible cord to have a connector only on the branch circuit / junction box side and terminate with open wires (hard-wired) into the luminaire as per (410.62 (C)(1)(b))?

3. What is the clear definition between flexible cord and fixture wire (section 402)? I only ask because the allowable types of cables for each are completely different (Table 400.4 flexible cords vs. Table 402.3 Fixture Wires). I need to know which Table is to be used when selecting a cable type.

4. Section 402.6 mentions that "fixture wires shall not be smaller than 18AWG". However in the flexible cords section (400.4 & 400.5) allow for sizes down to 27AWG. Which one is applicable when considering flexible cords between branch circuit / junction box to luminaire? Please note that this cord will have connectors on either end.

 

[RRJ]

1. 410.62 A luminaire shall be permitted to be connected with a cord terminating in a grounding-type attachment plug or busway plug.

Notice it says shall be permitted. It doesn’t have to be but it’s allowed if that’s the case.


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[RRJ]

2. 410.62c1 talks about for example a junction box above a ceiling tile with a piece of pipe less than 6” ,a cord connector ,a strained relief (kellam grip) and the cord connected to the canopy. It says “again” it shall be permitted (allowed).


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[Rock86]

Do you have a model or example of the fixture you are about to install? Is the fixture supplied with a cord or is this a custom fixture? Lastly, is the fixture equiped with a built in drive making the conductors 120V, or will the conductors be coming from a remote transformer supplying the fixture with a lower voltage?

 

[RRJ]

3 and 4 flexible cord are SO cords kind of like an extension cord but with a special jacket and fixture wires are the conductors that come inside the flexible metallic conduit.


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[EK001]

Thank you RRJ and Rock86 for the explanations.

You have answered most of my questions. Unfortunately, I'm not able to give you specific examples as pretty much any LED array/fixture can be used. We are in the connector business for these applications and this is the reason for all the questions.

Final question: If flexible cable is to be used between the branch circuit and the luminaire, should they be picked based on Table 400.4?

Also, is my assumption correct that the wire that comes with an LED fixture is referred to as fixture wire, i.e. it would be supplied by the LED manufacturer? Or is it something an installer would be responsible for?

 

[Rock86]

Thank you RRJ and Rock86 for the explanations.

You have answered most of my questions. Unfortunately, I'm not able to give you specific examples as pretty much any LED array/fixture can be used. We are in the connector business for these applications and this is the reason for all the questions.

Final question: If flexible cable is to be used between the branch circuit and the luminaire, should they be picked based on Table 400.4?

Also, is my assumption correct that the wire that comes with an LED fixture is referred to as fixture wire, i.e. it would be supplied by the LED manufacturer? Or is it something an installer would be responsible for?

NEC 400.10 Uses Permitted: (2) Wiring of luminaires.

With that said, I would say yes. I would also advice you look at Table 402.3 for "Fixture Wires". Also review 410 Part VI. "Wiring Luminaires." As I don't know your actual intent, I cannot advice you of the best option, but I hope that helps.

If the wire is supplied, it is fixture wiring, although there may not be markings to indicate which type of wiring it is.

 

[RRJ]

Thank you RRJ and Rock86 for the explanations.

You have answered most of my questions. Unfortunately, I'm not able to give you specific examples as pretty much any LED array/fixture can be used. We are in the connector business for these applications and this is the reason for all the questions.

Final question: If flexible cable is to be used between the branch circuit and the luminaire, should they be picked based on Table 400.4?

Also, is my assumption correct that the wire that comes with an LED fixture is referred to as fixture wire, i.e. it would be supplied by the LED manufacturer? Or is it something an installer would be responsible for?

I will recommend to look at the fixture specs for cable size, If they come with it, the manufacturer has to make sure the cable is big enough to supply the load on fixture. If it doesn’t come with it most likely the electrician will install 12/2 mc cable.


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