flourescent dimming

atomicpunk

Member
Location
washington dc
I have LED fixtures rated 277v with a controller that uses 0-10vdc to perform dimming function.
I have ordered dimmer switches that are rated to switch 277 vac and also have a 0-10vdc / 200ma max output for dimming.
My concern is that the switch does not appear to meet NEC 725.121 (A) requirements thus it will require class 1 wiring methods for the 0-10v, not a problem just my peers diagree and say class 2 is exceptable.
cooper electric sales and technical support are of no help
Can I get some help here?
 

AdrianWint

Senior Member
Location
Midlands, UK
Does it really use 0-10V or is it actually 1-10V?

These are totally different & incompatible systems.

0-10V is the 'theatre' way which involves a 0-10V analogue voltage passed between a lighting desk & a dimmer. This voltage is isolated & safe to touch.

1-10V is a common standard for dimmable fluorescent ballasts but doesn't use a voltage but a current. It is intended that these terminals are connected to a variable resistor (ie. potentiometer). The lower the resistance the more current flows & the brighter the lamp. These controls tend not to be isolated from the 277 supplying the fitting & hence must be considered as being 277V above ground.

Adrian
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I have LED fixtures rated 277v with a controller that uses 0-10vdc to perform dimming function.
I have ordered dimmer switches that are rated to switch 277 vac and also have a 0-10vdc / 200ma max output for dimming.
My concern is that the switch does not appear to meet NEC 725.121 (A) requirements thus it will require class 1 wiring methods for the 0-10v, not a problem just my peers diagree and say class 2 is exceptable.
cooper electric sales and technical support are of no help
Can I get some help here?
Which dimmer switches have you ordered?
 

atomicpunk

Member
Location
washington dc
LED dimming

LED dimming

I incorrectly stated flourescent dimming on my original post, but in fact I'm dimming LED fixtures.
The switch is a Cooper wiring device Devine series part #DF10P-C10 , it is the correct switch for the dimmable LED fixtures I'm using.
The switch delivers 0-10 vdc , 200 ma max, also switches 120/277 v
NEC 725.121(A) (3) does not appear to cover this device. (nor informational note)
I think this device meets standards for current limiting but is not listed class 2 or 3 compliant by code.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I incorrectly stated flourescent dimming on my original post, but in fact I'm dimming LED fixtures.
The switch is a Cooper wiring device Devine series part #DF10P-C10 , it is the correct switch for the dimmable LED fixtures I'm using.
The switch delivers 0-10 vdc , 200 ma max, also switches 120/277 v
NEC 725.121(A) (3) does not appear to cover this device. (nor informational note)
I think this device meets standards for current limiting but is not listed class 2 or 3 compliant by code.
I see nothing in the specifications that states the 0-10 volt control is class 2 or class 3 only. Are you being told otherwise?

http://www.cooperindustries.com/content/dam/public/wiringdevices/products/documents/spec_sheets2/DF10Pspecsheet.pdf
 

atomicpunk

Member
Location
washington dc
class 1 only

class 1 only

I have consulted with other electricians, and they had wired the 0-10 v using class 2 wiring methods.I believe code does not permit class2 wiring and thus I was looking for varification.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I have consulted with other electricians, and they had wired the 0-10 v using class 2 wiring methods.I believe code does not permit class2 wiring and thus I was looking for varification.
Looking at the manufacturer's literature I see no way to wire those as class 2 or class 3.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Looking at the manufacturer's literature I see no way to wire those as class 2 or class 3.
Agreed. Here is that literature. It's quite clear that the dimmer handles the full line voltage as well as providing a control voltage. You need to provide a 4 wire (neut and 3 hots) cable or two separate cables from the dimmer to the fixture which must be a class 1 wiring method. Apparently it's the violet and gray LV control that is confusing them and you. I see no way that that could be considered CL2 or 3 otherwise they would say so. Even if you could "reclassify" the wiring you would be back to a class 1 wiring method anyway.

http://www.cooperindustries.com/content/dam/public/wiringdevices/products/documents/spec_sheets2/DF10Pspecsheet.pdf

-Hal
 
Last edited:

GoldDigger

Moderator
Staff member
Looks like they sacrificed the ability to use class 2 wiring for avoiding the requirement for a neutral in the box and working in a three-way configuration.
The LV control wires may be at class 2 voltage and power levels but are not listed as class 2.

Sent from my XT1080 using Tapatalk
 

atomicpunk

Member
Location
washington dc
I suspected that it was not class 2 all along, my surprise is that with it being current limited to 200ma that cooper did not submit it as class2 power supply . It appears to meet the requirements of Chapter 9 table 11 (B)
Thanks to all
 

n1ist

Senior Member
Location
Massachusetts
In addition to current limiting, you need isolation between class 1 and class 2. Maybe they didn't have the space for sufficient clearances? In my last two designs, I had to use either optoisolators or transformer coupling and maintain 6.5mm spacing between any class2 and class1 components or traces on the board.
/mike
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Agreed. There is a lot more to making something like that CL2 compliant than just current and voltage limiting. Is it such a big deal to just use another run of 14/2?

-Hal
 
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