# LED Drivers - 0-10v dimming on multiple phases



## Dpcarls1598 (Dec 17, 2012)

Over the past year, I have been retrofitting classrooms with LED troffers from Cree - They have a 0-10v dimming ballast and I am using a Leviton slide dimmer.
Today I found one of the larger rooms, I found two circuits feeding the room (277v). Until now, I've been paralleling the 0-10v dimming circuits together with no issue, BUT, those have been on the same circuits. I haven't tried this yet and I can't get an answer from the manufacture of either the fixtures or the dimmers...
My question is if this will make a difference... Either damage to the driver/dimmer or flickering. I hesitate to just 'try it' and see what happens. 
I can rewire if necessary, but I feel I will run into this again. 
Any thoughts? Are the 0-10v dimming circuits independent of the line voltage input?


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## Electric_Light (Apr 6, 2010)

Ask Lutron.


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## gotshokd666 (Oct 17, 2012)

How are they being controlled now? Two switches?


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## Electric_Light (Apr 6, 2010)

I'd think that it'll be fine and you can parallel them up regardless of the phase but I'm not confident enough to swear by it. 

The 0-10v control section is heavily isolated and have no electrical connection to the rest of the ballast. UL and IEC are very particular about safety features like this. This means that the ballast will have an island on the board setup like a small AC adapter and all the communication is through the isolation transformer or an optical isolator so the line and signal do not see each other unless one of the sides get hit by lightning and arcs over. 

You and the guy sitting next to you at the airport could each be using a metal case laptop and be hooked up to two separate outlets on different phases served from the same 400/230 system. There's enough isolation that shock is not likely unless the both of you get the adapter wet and touch each other and the 0-10v control wiring is treated just like the secondary on AC adapters.

What you're NOT supposed to do is feed L1 and L2 from separate phases on a step dimming ballast that have three wires (N, L1 and L2).


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## Dpcarls1598 (Dec 17, 2012)

To answer the earlier post, they are on 4 switches, each half of the room controlled by a pair of switches doing inboard/outboard switching. Sooooo... I did hear from another contractor that they have done this before without issue. Their situation was an emergency circuit in the same room an a different phase but able to dim with the other lights. I intend to also have the same but adding an emergency relay (RIB) to bring the fixture to full brightness in a power failure. 
I completely agree that there must be substantial isolation between the class 1 and what I would gues are class 2 for the dimming circuit. 
Thanks to all for reading/replying - I will be finishing the room early next week. 
Dan


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## cuba_pete (Dec 8, 2011)

Electric_Light said:


> I'd think that it'll be fine and you can parallel them up regardless of the phase but I'm not confident enough to swear by it. You and the guy sitting next to you at the airport could each be using a metal case laptop and be hooked up to two separate outlets on different phases served from the same 400/230 system. There's enough isolation that shock is not likely unless the both of you get the adapter wet and touch each other and the 0-10v control wiring is treated just like the secondary on AC adapters. What you're NOT supposed to do is feed L1 and L2 from separate phases on a step dimming ballast that have three wires (N, L1 and L2).


These are the exact types of situations I test for at my place of work. We have over twenty SDS' in my facility. Keeping the loads balanced and monitoring all of the possible ground/current loops can be a full time job. Years gone by and too many hands in the mix have created some interesting situations.


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## amigi968 (May 24, 2008)

I'm doing a very large stadium right now in Central Florida. All of the lighting is LED, much of it in large formations with multiple circuits but only one set of 10v dimming wires. No issue at all. 
Lutron's Grafik Eye and EcoPanels can control dozens of circuits with only the two wires through the EcoBus.


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## BulbmartDepot (Jan 19, 2015)

Usually the LED troffers have two wires that are for line voltage to power the unit up. Then they have another two wires that are for dimming purpose only. The two wires that are for dimming you can use regular low voltage 18 gauge thermostat wire. Most manufactures make 1-10v dimmers but it must be a specific LED 1-10v dimmer.

Please see the link below. I also included a link to my company website if you need any products or help just let me know.

http://www.lutron.com/TechnicalDocumentLibrary/Diva_0-10Vsubmittal.pdf


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## freeagnt54 (Aug 6, 2008)

I've never had a problem putting multiple circuits on the same 0-10v dimming circuit


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