Class 2 wiring systems with lighting power

[gedgington]

Has anyone had issues with running a Class 2 0-10 dimming conductors (600v rated) in the same raceway as the power conductors supply the fixture. Looking at Art. 725.136, I could not find an application there that supported the concept of 600v making a difference.

 

[Dennis Alwon]

My understanding is that, in general, if you have class 2 wiring then it cannot be in the same raceway as power conductors. There are ways to do it as explained in 725.136(D)-- this may be a way to make it compliant with the class 2 0-10v dimming. At least it sounds like it would be compliant

 

[infinity]

In some case, like with Lutron products, you can change the Class 2 to Class 1 and use the same raceway or cable for power and control.

 

[MasterTheNEC]

Hello Guys,

Well I can speak to this. Section 725.136(I)(2) covers one of the conditions of which you speak and it states that all of the electric light and power circuit conductors must be permanently separated from all of the Class 2 and Class 3 circuit conductors by a continuous and firmly fixed nonconductive, such as extruded flexible tubing, in addition to the insulation on the conductors itself.

So if you have an MC Cable with 600V rated conductors within a PVC extruded binding jacket, over a twisted pair (also 600V) installed inside of the metal armor along with the power and lighting conductors then the PVC binder, fixed extruded jacket and insulated twisted conductors would provide the separation to meet clause 725.136(I)(2).

In fact, theses products are already out on the market and UL-1569 permits the application.

 

[augie47]

In some case, like with Lutron products, you can change the Class 2 to Class 1 and use the same raceway or cable for power and control.

I spent a ton of hours with Lutron and Code gurus where I had a similar concern.
Even to this day I can't say I have a thorough picture but, in my case we looked at
Exception 2 to 725.130 which allows us to classify the Class 2 circuits as Class 1 and 725.48 allows Class1 circuits to share a raceway or cable where the equipment is functionally associated, but that doesn't help when your LV wiring method is a Class 2 cable.
In addition, on my installation the cables were sharing the same j box and the lighting circuit was 277v eliminating our using 725.136(D).
I find Paul's cable in Post 4 to be very interesting. I'm unsure how to address that in a j box and perhaps he can help us with that.
I was faced with a load of fixtures that had a mutliwire pendant type cord to supply power and Lutron diming controls. The E/C needed to use that cord. The only solution I forund was to install the Lutron wiring as Class 1 but someone here may show us another solution.

 

[infinity]

I spent a ton of hours with Lutron and Code gurus where I had a similar concern.
Even to this day I can't say I have a thorough picture but, in my case we looked at
Exception 2 to 725.130 which allows us to classify the Class 2 circuits as Class 1 and 725.48 allows Class1 circuits to share a raceway or cable where the equipment is functionally associated, but that doesn't help when your LV wiring method is a Class 2 cable.
In addition, on my installation the cables were sharing the same j box and the lighting circuit was 277v eliminating our using 725.136(D).
I find Paul's cable in Post 4 to be very interesting. I'm unsure how to address that in a j box and perhaps he can help us with that.
I was faced with a load of fixtures that had a mutliwire pendant type cord to supply power and Lutron diming controls. The E/C needed to use that cord. The only solution I forund was to install the Lutron wiring as Class 1 but someone here may show us another solution.

It's common with Lutron to just reclassify as Class 1 and use 5 conductor MC cable or 600 volt conductors for the Class 1 with the power conductors in the same raceway. We've installed thousands of fixtures this way.

 

[augie47]

It's common with Lutron to just reclassify as Class 1 and use 5 conductor MC cable or 600 volt conductors for the Class 1 with the power conductors in the same raceway. We've installed thousands of fixtures this way.

Seems the best solution when you have to mix the Art 725 with power circuits.

I confuse myself with Art 725 at times. Does 725.48 (B)(1) allow the multiconductor cord/canopy that some fixture manufacturers supply ?

 

[GoldDigger]

It's common with Lutron to just reclassify as Class 1 and use 5 conductor MC cable or 600 volt conductors for the Class 1 with the power conductors in the same raceway. We've installed thousands of fixtures this way.

This works only because the safety of the dimmer is not dependent on the use of a Class 2 power supply. That is, the Lutron parts are listed for either Class 1 or Class 2 control, although their controller happens to use Class 2 output.
Some other brand that is only listed for Class 2 would not allow this reclassification.

 

[pjholguin]

Greetings,
How does one go about getting a class change? :?

In some case, like with Lutron products, you can change the Class 2 to Class 1 and use the same raceway or cable for power and control.

 

[infinity]

Some info from Lutron:

http://www.lutron.com/TechnicalDocumentLibrary/AppNote142.pdf

 

[MasterTheNEC]

I spent a ton of hours with Lutron and Code gurus where I had a similar concern.
Even to this day I can't say I have a thorough picture but, in my case we looked at
Exception 2 to 725.130 which allows us to classify the Class 2 circuits as Class 1 and 725.48 allows Class1 circuits to share a raceway or cable where the equipment is functionally associated, but that doesn't help when your LV wiring method is a Class 2 cable.
In addition, on my installation the cables were sharing the same j box and the lighting circuit was 277v eliminating our using 725.136(D).
I find Paul's cable in Post 4 to be very interesting. I'm unsure how to address that in a j box and perhaps he can help us with that.
I was faced with a load of fixtures that had a mutliwire pendant type cord to supply power and Lutron diming controls. The E/C needed to use that cord. The only solution I forund was to install the Lutron wiring as Class 1 but someone here may show us another solution.

Quite simple, if the assembly meets 725.136(I)(2) then no separation is needed. The general rule of (I) calls for a separation unless item (2) is met in which the separation is not required. As for the luminaire, the .25 separation will take place by the installer and by the design of the smart luminaire manufacturer. From a cable manufacturers perspective, it is compliant to the luminaire, the installer and the manufacturer of the luminaire will handle their part of compliance.

FYI- I guess I should also add, the insulation on the Class 2 or 3 conductors are also 600V rated just like the lighting and power circuit conductors.

 

[augie47]

Quite simple, if the assembly meets 725.136(I)(2) then no separation is needed. The general rule of (I) calls for a separation unless item (2) is met in which the separation is not required. As for the luminaire, the .25 separation will take place by the installer and by the design of the smart luminaire manufacturer. From a cable manufacturers perspective, it is compliant to the luminaire, the installer and the manufacturer of the luminaire will handle their part of compliance.

FYI- I guess I should also add, the insulation on the Class 2 or 3 conductors are also 600V rated just like the lighting and power circuit conductors.

'

" Quite simple" perhaps to you
Sometimes for me the trees hide in that big ole forest.
If one chooses to utlize the Class 2 wiring methods, a fixture employing a cord/canopy arrangement would need to have a cord in compliance with 725.136(I) and comply with 725.136(D) as far as the outlet box.
Is that correct ?

 

[MasterTheNEC]

'

" Quite simple" perhaps to you
Sometimes for me the trees hide in that big ole forest.
If one chooses to utlize the Class 2 wiring methods, a fixture employing a cord/canopy arrangement would need to have a cord in compliance with 725.136(I) and comply with 725.136(D) as far as the outlet box.
Is that correct ?

From a wire and cable perspective, the issue of compliance for the construction of a hybrid cable that is in accordance with NEC 725.136(I)(2) was the main focus. Once the compliant product enters the "associated system within enclosures" then and only then does an separation need to take place. It would by my belief that upon entering such an enclosure area of a smart luminaire that it would be rather easy to provide the minimum .25 in. separation as the conductors are "routed" as specified in 725.130(D)(1).

However, with that said it is the belief (and I use that as an industry belief) that item(I) for other applications are what governs this type of product and as long as their is that nonconductive, binder jacket along with individual conductor insulation, all with an equal rating of 600V that the separation is a moot issue. With that said, if you did invoke 725.130(D)(1), once the lighting and power conductors and the jacketed, twisted Class 2 or 3 conductors entered the enclosure area of the luminaire, the minimal .25 in separation would be very simple to achieve as you "route" the conductors to maintain the spacing if that is the inspectors wish.

And sorry for the simple statement....was kinda saying the concept in developing the product was simple. In fact, ...it's just an allowable adaptation of being in accordance with UL-1569.

 

[augie47]

Thanks.
Do you have a link to a complying cable ?

 

[MasterTheNEC]

I will let you see an established one already posted on the internet. Rather than be self promotional I will post someone else's product.


http://www.afcweb.com/announcing-mc-luminary

 

[infinity]

So this cable can be used as Class 2 even without any separation?

 

[MasterTheNEC]

It's common with Lutron to just reclassify as Class 1 and use 5 conductor MC cable or 600 volt conductors for the Class 1 with the power conductors in the same raceway. We've installed thousands of fixtures this way.

Indeed is one way of doing it. The problem is that if you reclassify the circuit as Class 1 then you must treat the entire circuit as a Class 1 as I am more than sure you know. The problem comes when you follow the directions in the exception and remove the markings per 725.124. Then what if the dimming controllers instructions call for only Class 2 wiring to be terminated to the equipment and you have now reclassified it as Class 1. Does this not violate the listings of the dimming equipment and associated accessories?

The solution found in 725.136(I)(2) is to permit the Class 2 or 3 circuits to remain as they are, terminate as they are intended into equipment that has been evaluated and listed as Class 2 components. If you speak with some of the manufacturers (GE Lighting for example) they will say their terminals, equipment, components and so on are Class 2 and if not they will be marked when it is acceptable (smart loops and such) to be Class 1 as an option.

It is a fine line when doing reclassification as permitted in 725.130(A) Ex.2. The action assumes the installer knows how to reclassify and meet the other requirements explained in part II of 725 and understands the consequences in the actions they take.

 

[MasterTheNEC]

So this cable can be used as Class 2 even without any separation?

it does have separation as demanded by 725.136(I)(2). The PVC Binder Jacket on the twisted pair is fixed to the conductors along with their inherent insulation that provides the needed separation. Once you reach the enclosure that is part of the equipment then you are out of the combined raceway or cable allowance and then maintaining the .25 separation is the task of the installer.

 

[infinity]

Indeed is one way of doing it. The problem is that if you reclassify the circuit as Class 1 then you must treat the entire circuit as a Class 1 as I am more than sure you know. The problem comes when you follow the directions in the exception and remove the markings per 725.124. Then what if the dimming controllers instructions call for only Class 2 wiring to be terminated to the equipment and you have now reclassified it as Class 1. Does this not violate the listings of the dimming equipment and associated accessories?

In the case of the Lutron components that I mentioned they allow the reclassification as their equipment is setup that way. The way these systems are wired that makes it quite a bit easier, especially with pendants that have 5-wire cords like Augie mentioned.

 

[MasterTheNEC]

I also think I need to make sure everyone understands why 725.136(I)(2) can be used. The nature of 725.136 is to define separating for Electric, Power, Class 1 and so on circuits from Class 2 or 3 circuits. Since we are talking about a cable (or raceway if you will), you will notice that items (B) through (H) do not deal with raceways or cables in terms of combing the circuits and the separation needed. So item (I) is what ends up dealing with the issue.

If not for the exceptions to item (I) you would also not see products like Type NMS [see 334.116] or other hybrid cables so the exceptions are very important to manufacturers who intend to make these types of products. It would be cheaper to produce the MC cable with power conductors with THHN/THWN-2, 600V insulation and do the same 600V insulation with the 18 AWG TFN conductors as well....and HOPE the end user knows how to reclassify the 18 AWG intended Class 2 conductors as Class 1....I guess that's the chance some manufacturers wish to take and some do not wish to leave it up to the end user to do additional things. To each his own I guess.