What type of wire for 0-10 dimming installation explained better

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Journeyman Lineman / Distribution design and EC in my spare time
Hi everyone.

I recently posted a similar question, thought I would explain my question better. I am wiring a residential large shop, so open ceilings and romex for power. I was going to use a Lutron 0-10 dimmer / switch combo so the 0-10 wire will need to be rated to be installed in an switch box that will have 240v in it. 240v only because I will have two separate circuits feeding multiple rows of lights. What kind of wire would be the best for this installation? I am running yellow 12-2 for everything power so I thought I would run white 14-2 for 0-10. Would 14-2 romex be acceptable to be ran in a switch box?
 

M_J_C

Member
I try not to endorse a brand or specific product, but sometimes the others haven't caught up yet. This cable assembly is what I've seen in commercial 0-10v dimming installations:

http://mcpcsduo.southwire.com/

The lighting controllers were in panels specific to the product, so I didn't have to worry about insulation ratings/barriers/conductor spacing issues that you would have to be addressed in a wallbox.
 

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Journeyman Lineman / Distribution design and EC in my spare time
14 guage Romex is fine but it's overkill and you don't need the egc. You should be able to get 16 or 18 guage control cable, most likely in the standard purple and grey at your supply house.
Thanks for the reply ActionDave, are most rated to be installed in class 1 installations? If I ask my supply house guys I am sure they would look at me cross eyed?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I don't believe nm cable is compliant as it is not rated class II but rather class I, as I understand it. If you use chapter 3 wiring method then the entire install must be a chapter 3 install. Sometimes that could work with 0-10v dimming....
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
There is no restriction on using NM or any other Chapter 3 wiring method for a Class 2 or 3 circuit. You could use 5kV cable if you wanted too....of course that might be a bit costly.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
You don't seem to understand that your 0-10V control cable doesn't have to be listed for 120 or 240V. The fixtures and switches will provide the necessary separation between the CL2 wiring and the power.

The only problem comes in when you want to run the control wiring with the power in the same cable or raceway. But you aren't doing that.

-Hal
 

GoldDigger

Moderator
Staff member
I don't believe nm cable is compliant as it is not rated class II but rather class I, as I understand it. If you use chapter 3 wiring method then the entire install must be a chapter 3 install. Sometimes that could work with 0-10v dimming....
My understanding is that you can use Chapter 3 methods without restriction on what you may use for other parts of the Class 2 or 3 circuit.
On the other hand if you need to reclassify the circuit as Class 1 for any reason (such as sharing a raceway with power) you must treat the entire circuit as Class 1 and use exclusively Chapter 3 methods.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
My understanding is that you can use Chapter 3 methods without restriction on what you may use for other parts of the Class 2 or 3 circuit.
On the other hand if you need to reclassify the circuit as Class 1 for any reason (such as sharing a raceway with power) you must treat the entire circuit as Class 1 and use exclusively Chapter 3 methods.
Aren't you changing the circuit to class 1 by using chapter 3 wiring? Not sure how you can change the circuit to class 1 when a class 2 trany is involved. I know that class 3 wiring is rated for class 2 but class 2 cannot be used in class 3. I assumed that class 1 would have the same restriction
 

oldsparky52

Senior Member
Aren't you changing the circuit to class 1 by using chapter 3 wiring?
I've never heard that before. The wiring method does not determine the circuit class AFAIK, I always thought the equipment determined the class which determined the wiring method requirements. I was also under the impression that you could use a class 1 wiring method for a class 2 circuit w/out modifications of ... anything.

But, ... You Dennis are way more savvy than I.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
I've never heard that before. The wiring method does not determine the circuit class AFAIK, I always thought the equipment determined the class which determined the wiring method requirements. I was also under the impression that you could use a class 1 wiring method for a class 2 circuit w/out modifications of ... anything.
Again, correct!

Dennis Alwon said:
Aren't you changing the circuit to class 1 by using chapter 3 wiring? Not sure how you can change the circuit to class 1 when a class 2 trany is involved. I know that class 3 wiring is rated for class 2 but class 2 cannot be used in class 3. I assumed that class 1 would have the same restriction
That would only happen if you reclassify in order to run the CL2 wiring with the power or Class 1 conductors. If you used 14/2 NM for a thermostat it's still a CL2 circuit.

Not sure how you can change the circuit to class 1 when a class 2 trany is involved.
Sharpie! :happyyes:

-Hal
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
When I read art 411 I see this and #3 says wiring methods of Chapter 3. I cannot run nm cable and not terminate in a box if I use chapter 3 methods... This is why I am confused by the comments above

411.6(D) Insulated Conductors. 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 installed
not less than 2.1 m (7 ft) above the finished floor
unless the system is specifically listed for a lower installation
height.
(3) Wiring methods described in Chapter 3.
 

oldsparky52

Senior Member
When I read art 411 I see this and #3 says wiring methods of Chapter 3. I cannot run nm cable and not terminate in a box if I use chapter 3 methods... This is why I am confused by the comments above
Now I'm confused, why can't you use nm (for the class 2 or 3 circuits) and make the class 2 or 3 connections in a box? I'm assuming the box will not have class 1 wiring.

I re read Dennis's post and I see I misunderstood, but still, why can't you use nm and not terminate in a box?
 
Last edited:

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Art 411 only relates to low voltage lighting systems operating at 30 volts or less. The language seems to indicate that CL2 conductors need to be run as a Chapter 3 wiring method if you don't use a CL2 cable. What they are actually saying is that for systems larger than CL2, Chapter 3 wiring methods are required.

-Hal
 

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Journeyman Lineman / Distribution design and EC in my spare time
Art 411 only relates to low voltage lighting systems operating at 30 volts or less. The language seems to indicate that CL2 conductors need to be run as a Chapter 3 wiring method if you don't use a CL2 cable. What they are actually saying is that for systems larger than CL2, Chapter 3 wiring methods are required.

-Hal
So Hal, I ran all of the 0-10V wiring in 14-2 romex because it was cheaper than buying 600v rated 18-2 sheathed cable. I kept the 0-10 separate everywhere but it will terminate in the switch and fixture with the 120v circuit. Do you think this is code compliant? There seems to be a lot of confusion on this topic. The industry hasn't caught up to these types of lights in a romex installation. You just cant find wire for it. I found one person that had purple / gray 18-2 and like I said it was expensive.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
You didn't need 600V rated wiring for the 0-10V. Could have used 18/2 thermostat wire. Tried to explain that to you several times!

The 14/2 NM to me would look like DIY work. Sorry.

Yeah, there's a lot of confusion. We have this question about once a month and nobody understands it yet! It isn't that difficult.


-Hal
 

GerryB

Senior Member
You didn't need 600V rated wiring for the 0-10V. Could have used 18/2 thermostat wire. Tried to explain that to you several times!

The 14/2 NM to me would look like DIY work. Sorry.

Yeah, there's a lot of confusion. We have this question about once a month and nobody understands it yet! It isn't that difficult.


-Hal
Southwire now makes luminaire cable in Romex. Both the MC and the romex have 600 volt rated insulation on the dimming conductors. I thought that was because the dimmer switches have line and lv tails on them and how can you get 1/4 inch separation? My understanding is you have to keep the lv out of the box. You can run bell wire to a power pack, like a doorbell transformer, line inside lv outside.At least that is my understanding. If the cable that is listed for 0-10 volt dimming has all 600 volt conductors there must be a reason, no?
 

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Journeyman Lineman / Distribution design and EC in my spare time
You didn't need 600V rated wiring for the 0-10V. Could have used 18/2 thermostat wire. Tried to explain that to you several times!

The 14/2 NM to me would look like DIY work. Sorry.

Yeah, there's a lot of confusion. We have this question about once a month and nobody understands it yet! It isn't that difficult.


-Hal
The LV wiring will be in the same switch box now. When I opened the light fixture the LV and power conductors are not in separate compartments like Ive seen in other fixtures and the LV leads are THHN so I made the decision on the job to run the LV in romex. Is there anything against code here? If so I just cost myself a lot of time and money!
 

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Journeyman Lineman / Distribution design and EC in my spare time
Southwire now makes luminaire cable in Romex. Both the MC and the romex have 600 volt rated insulation on the dimming conductors. I thought that was because the dimmer switches have line and lv tails on them and how can you get 1/4 inch separation? My understanding is you have to keep the lv out of the box. You can run bell wire to a power pack, like a doorbell transformer, line inside lv outside.At least that is my understanding. If the cable that is listed for 0-10 volt dimming has all 600 volt conductors there must be a reason, no?
Also, the difficult part here is that I have seen a failed inspection for running CL2 wiring in the same enclosure as CL1. Different raceway just same enclosure regardless of 1/4" separation or not.
 
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