# 0-10vdc dimming



## power (Feb 27, 2012)

We have a bank of lights that is presently on 0-10vdc dimming, from a dimming cabinet. For some reason, the dimming controller's output (0-10vdc) keeps failing to .5vdc, meaning the lights are VERY dim. If the grey/purple conductors are removed from the dimming output module, the module's output voltage climbs to it's preset 10vdc (full bright ON).

My gut tells me one of the lighting bank's ballasts is messed up, and it's 0-10vdc isn't working and "back corrupting" the dimming module & the entire 0-10vdc dimming circuit, thus, affecting all other lights on it's associated line.

Has anyone seen this before? Any idea's?


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## joe-nwt (Mar 28, 2019)

Haven't seen it before but if you're right, divide and conquer will be your way forward.


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## MikeFL (Apr 16, 2016)

0.5VDC on a 0-10VDC circuit means OFF via dimming.
Not sure why dim glow on yours. Try driving 0.4V, 0.3V, etc. and see if you get it to "dim to off".


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## Leg wrestle champ (Nov 14, 2012)

Are your drivers constant voltage drivers or constant current? Is the 0-10 compatible with that supply?


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## MikeFL (Apr 16, 2016)

0V means drive 100% because it thinks nothing is connected.
That's why you need that fractional volt to dim to off. 
Each different model can vary as to what that fraction is. Find a datasheet on the light.


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## splatz (May 23, 2015)

Is this a lighting panel with relays out that have power and 0-10V for each lighting circuit? Is it software controlled, scheduled, etc., or is all the control from the dimmers / switches? Is there any ambient light sensor involved?


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## paulengr (Oct 8, 2017)

power said:


> We have a bank of lights that is presently on 0-10vdc dimming, from a dimming cabinet. For some reason, the dimming controller's output (0-10vdc) keeps failing to .5vdc, meaning the lights are VERY dim. If the grey/purple conductors are removed from the dimming output module, the module's output voltage climbs to it's preset 10vdc (full bright ON).
> 
> My gut tells me one of the lighting bank's ballasts is messed up, and it's 0-10vdc isn't working and "back corrupting" the dimming module & the entire 0-10vdc dimming circuit, thus, affecting all other lights on it's associated line.
> 
> Has anyone seen this before? Any idea's?


Loads will normally measure very high resistance. Generally speaking it’s going to be the input to a transistor follower circuit so that the controller sees 10k or more. This is one thing you can test for with a meter set on ohms.

If the whole system isn’t 1,000 ohms or more as a load you could have a shirt somewhere. Otherwise most likely it’s the controller.


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## Slay301 (Apr 23, 2018)

paulengr said:


> Loads will normally measure very high resistance. Generally speaking it’s going to be the input to a transistor follower circuit so that the controller sees 10k or more. This is one thing you can test for with a meter set on ohms.
> 
> If the whole system isn’t 1,000 ohms or more as a load you could have a shirt somewhere. Otherwise most likely it’s the controller.


I’m sure he has plenty of shirts in his closet


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## HertzHound (Jan 22, 2019)

I have seen where one fixture was wired backwards and it takes down the whole string. Purple and grey can be hard to distinguish in the dim lighting of construction jobs.

So if one driver goes bad, I can see it taking down the whole switch leg. Divide and conquer like mentioned.

As far as I know, the driver creates the 10v, not the controls/dimmer. I never tested the output of a dimmer’s purple & grey. I thought it was just a variable resistor or some other electronic control? Same with a 0-10v module in a dimmer rack. So a bunch of lights with their purple and grey paralleled, would still have 10v, and somehow paralleling all these power supplies doesn’t do any damage.


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## paulengr (Oct 8, 2017)

Slay301 said:


> I’m sure he has plenty of shirts in his closet


SIRI can’t spell.


Sent from my iPhone using Tapatalk


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## paulengr (Oct 8, 2017)

HertzHound said:


> I have seen where one fixture was wired backwards and it takes down the whole string. Purple and grey can be hard to distinguish in the dim lighting of construction jobs.
> 
> So if one driver goes bad, I can see it taking down the whole switch leg. Divide and conquer like mentioned.
> 
> As far as I know, the driver creates the 10v, not the controls/dimmer. I never tested the output of a dimmer’s purple & grey. I thought it was just a variable resistor or some other electronic control? Same with a 0-10v module in a dimmer rack. So a bunch of lights with their purple and grey paralleled, would still have 10v, and somehow paralleling all these power supplies doesn’t do any damage.


You are right I forgot it is designed to feed a pot.

So yeah you’d have to split them up to find it and maybe buy a cheap pot (dimmer switch) to find it.


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## splatz (May 23, 2015)

HertzHound said:


> So if one driver goes bad, I can see it taking down the whole switch leg. Divide and conquer like mentioned.


I am trying to think of a wiring fault that would occasionally send a consistent 0.5VDC - the dim off level - to the lights. A faulty dimmer, maybe. Also possible, a dimmer wired in the wrong place, so someone's trying to dim lights in a different room and operating that dimmer and wondering why nothing is happening. 

If it's a lighting panel with a brain (controller), things change and troubleshooting this becomes a bit harder. If the 0-10V is supplied at the source, the brain may dim the circuit, and the dimmers wire back to inputs on the controller. The controller may be sending 0.5VDC because someone accidentally made a schedule in the software to turn the lights off unless overridden. 

If there are ambient light sensors, and the system interacts with the dimmers, and a light or reflection shines on the ambient light sensor, it could turn off the lights until that stray light source goes away. 

If the problem is intermittent, I'd want to disconnect the purple and gray pair at the source and monitor the outputs with none of the field wiring connected. See if it still goes to 0.5V when there is nothing connected. How would you monitor the 0-10V output?


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## power (Feb 27, 2012)

Leg wrestle champ said:


> Are your drivers constant voltage drivers or constant current? Is the 0-10 compatible with that supply?


Unfortunately, I don't know if they are constant voltage or constant current! This is a large dimming system in a major hotel (Marriot), so it will be whatever would typically be needed to such a building where multiple lighting zones are set (by a remote computer) to illuminate according to morning, lunch, dinner, late evening environements.

Regards the compatibility, these lights worked as they are for about 4 years, so there mustn't be a compatibility issue.


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## power (Feb 27, 2012)

splatz said:


> I am trying to think of a wiring fault that would occasionally send a consistent 0.5VDC - the dim off level - to the lights. A faulty dimmer, maybe. Also possible, a dimmer wired in the wrong place, so someone's trying to dim lights in a different room and operating that dimmer and wondering why nothing is happening.
> 
> If it's a lighting panel with a brain (controller), things change and troubleshooting this becomes a bit harder. If the 0-10V is supplied at the source, the brain may dim the circuit, and the dimmers wire back to inputs on the controller. The controller may be sending 0.5VDC because someone accidentally made a schedule in the software to turn the lights off unless overridden.
> 
> ...


This is a major hotel dimming panel, with modules that are preprogrammed by a remote computer. Too, this is not an issue of the lights being controlled from various locations, and the controller is getting "confused", no, their only controlled by the restaurant staff in the hotel (breakfast setting, lunch, dinner, and late night setting). When we move the problem bank of potlights onto a different output of the dimming module that has the same schedule, the problem follows to the new module. Herein is why I think it's a field wiring problem with one/more of the pot light drivers. With the purple/grey wires disconnected, the output module return the 0-10vdc output that it should as per it's schedule.


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## macmikeman (Jan 23, 2007)

Slay301 said:


> I’m sure he has plenty of shirts in his closet


Macmike suddenly races to his picture volumes looking for a shot of all his aloha shirts in his closet , there's like 50 of em in there, all Cook Street ........ They sure messed up the photo albums when they "upgraded the forum system"....


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## MikeFL (Apr 16, 2016)

4 years is 35k hours if they burn 24/7.
Did someone sell them some el-cheapos and maybe they're at end of life?


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## macmikeman (Jan 23, 2007)

Ahhhhh


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## power (Feb 27, 2012)

@macmikeman - OMG - Only a member with 35K+ posts would have that many aloha shirts....WOW. Obviously, you like em'.

It was determined (with the assistance of ICLS Lighting Systems) that one (of 44) of the pot lights has a faulty 0-10vdc circuit, and it is "back corrupting" the entire dimming zone. As this "bad light" is connected in parallel with 43 other pot's, the dimming module doesn't like it, and drops to .5vdc (very dim). So, unfortunately, we'll have to disconnect the lights at about 50% along the feed, then 25%, then 10%, to try to identify the "culprit" pot light. Unfortunate thing is, from the ground (inside the hotel's restaurant), all 44 of the pot's are appearing fine. I was hoping the "culprit" pot would manifest itself somehow, but nope, it's not!


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## MikeFL (Apr 16, 2016)

Why not just one at a time?

Disconnect one lead, is problem still there, yes, reconnect and move to the next one.

My guess is something failed closed and it's pulling current. 
Industry standard convention on 0-10 is 2mA max draw from a single fixture.


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## Almost Retired (Sep 14, 2021)

MikeFL said:


> Why not just one at a time?
> 
> Disconnect one lead, is problem still there, yes, reconnect and move to the next one.
> 
> ...


i prefer the divide and conquer method
take loose the back half and see which half
continue halving to narrow it down


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