# Dimming Occupancy Sensor Questions



## MikeFL (Apr 16, 2016)

Question: How far can you run on that 0-10V line, and how many fixtures can you drive with it?
When I get asked I tell them you need one control per fixture or per post (in a parking lot) where you may have 4 fixtures on a post.
I tell them you can't drive 0-10V dimming of an entire 45 acre shopping center off one 0-10V dimmer in the electric room, because it's going to have VD and inconsistent dimming levels.

Everyone agree? 
Anyone disagree? 

I believe this thread is hitting on this very issue.


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## SWDweller (Dec 9, 2020)

If your bidding the project, bid it like the drawings tell you. If the controls are not spelled out to you needs then ask the engineer a question? We call them RFI's request for information. 

I think it is a piss poor concept as you describe it , 5 sensors 12 fixtures, sensors mounted by the doors. Any windows to the outside? Facing which direction, south or west will be a real problem. Are the windows near a well traveled road that is east and west?

I put some in for one of our managers, she was near a well traveled road going east and west. When the sun was at the right angle towards the afternoons the light would reflect off of the chrome on the passing vehicles and cause the lights to ramp up and down. 
Oh you do not like this feature. Installed exactly what you asked for and where you wanted it. 
Ended up disconnecting the system which is what you will be doing to this office area. 
Dimming office areas is just stupid. Most workers in that environment need more lumens not less. You do not state the lumens from each fixture, most office areas at desk height need 


> 30 lumens per sqft. Fine work, lots of text reading, more.


Get a copy of the photometrics for the fixtures would be interesting to see if they work as well as the designer thinks.


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## wiz1997 (Mar 30, 2021)

Little bit I know.

Lights can be controlled by two different dimmers but they must be of the slave/master type.

We have a GE lighting control panel at work that controls with occupancy sensors, dimmers and a time clock all in one unit.

This controller controls lighting in our production area.

Have to wait until Monday to get any info.

In our conference room we have 9 ballest fixtures on one 0 to 10 volt Levinton dimmer switch, believe you can have up to 20.

Suggest getting more input from the customer or whomever came up with the drawing.

Do they specify the devices?

If so, providing us with that info would help us help you.


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## Viggmundir (Sep 13, 2019)

MikeFL said:


> Question: How far can you run on that 0-10V line, and how many fixtures can you drive with it?
> When I get asked I tell them you need one control per fixture or per post (in a parking lot) where you may have 4 fixtures on a post.
> I tell them you can't drive 0-10V dimming of an entire 45 acre shopping center off one 0-10V dimmer in the electric room, because it's going to have VD and inconsistent dimming levels.
> 
> ...


Some of the reading up on it I've done, guys were saying they were doing a whole Walmart or home depot on 1 or 2 dimmers. A shopping center would seem extreme to do it on one dimmer though.
As for distance, a few product spec sheets say around 300ft.


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## Viggmundir (Sep 13, 2019)

SWDweller said:


> If your bidding the project, bid it like the drawings tell you. If the controls are not spelled out to you needs then ask the engineer a question? We call them RFI's request for information.
> 
> I think it is a piss poor concept as you describe it , 5 sensors 12 fixtures, sensors mounted by the doors. Any windows to the outside? Facing which direction, south or west will be a real problem. Are the windows near a well traveled road that is east and west?
> 
> ...


Sorry, it's not an office. The building is being called an activity center. It's an open room, used for volleyball, the double door out the left side goes to a small kitchen, so gatherings and the odd meal will happen as well. No windows in this room, unless there are windows in the exterior doors(I haven't seen a door schedule).


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## Viggmundir (Sep 13, 2019)

wiz1997 said:


> Little bit I know.
> 
> Lights can be controlled by two different dimmers but they must be of the slave/master type.
> 
> ...


I saw some stuff for the master/slave dimmers, but not also an occupancy sensor.

For number of fixtures on one dimmer, it has to do with the source sinking ability of the dimmer. The standard for lights is 2mA per fixture, and I saw some dimmers that could do 80mA, so that would be 40 fixtures per dimmer. Some would be less.

The closest I've got to working on a lighting control panel is the old GE low voltage switching setups done in the 70's. Newer versions just don't seem to be popular out where I am, or at least I don't have those customers lol. I could understand if all of these sensors and switches fed into a control panel, but there is nothing in the plans or specs for a lighting control system.

If the devices were specified, I'd at least know where to look! They do have some 0-10v dimmers specified as options, but they are all dimmer only, and this room (and 9 other rooms in the building) specifically calls for a combo dimmer occupancy switch.


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## wiz1997 (Mar 30, 2021)

On the drawing what does the 2 next to OS indicate?

Does the OS in the hallway control just the light in the hallway?

I'd also have to ask about the lighting on the ramps, landings and the stairs.

They may need more lighting according to any handicap accessibility requirements in your area.

This is the dimmer, occupancy sensor I have installed in our conference rooms.

But only controlling one circuit.






Smart Sensor - Occupancy Sensor - Vacancy Sensor - ODD10-IDW


Smart Sensor, Passive Infrared, Antimicrobial, 0-10V Dimming, App configurable; Auto-ON/Auto-OFF or Manual-ON/Auto-OFF, neutral wire required, 120/208/220/230/240/277VAC, 50/60Hz; White. Wall plate sold separately.




www.leviton.com


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## LGLS (Nov 10, 2007)

Viggmundir said:


> Bidding a set of plans right now, and it has dimming occupancy sensors. I haven't worked with them before.
> 
> 80'x50' open room with 20' ceiling is lit by 12 150W LED UFO highbays with 0-10V dimming, split between 2 separate power circuits, evenly spaced.
> 5 combination dimming/occupancy sensors are wall mounted beside entrance doors into this room, with 3 all at one end of the room. How do I wire these things? And what things should I use?
> ...


Unless there’s another more detailed drawing, I’m not seeing what you’re seeing. I see an OS in a square at every door, 4 out of 5 doors also with a 2 in a circle. 2 in a circle means dimmer, for all the lighting, where are these dimmers?

Where are you seeing 3 OCs all at one end of the room? I see one at every exit/entrance only A space like this “Atrium” (college, school campus?) and this large is going to need ceiling mounted occupancy sensors, lest someone walking through be plunged into darkness 1/2 way through the space.

Seems the designer is using small executive conference room mentality applied to a massive all purpose public space setting.


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## MikeFL (Apr 16, 2016)

Viggmundir said:


> Some of the reading up on it I've done, guys were saying they were doing a whole Walmart or home depot on 1 or 2 dimmers. A shopping center would seem extreme to do it on one dimmer though.
> As for distance, a few product spec sheets say around 300ft.


Thanks!

You inspired me to do some work on it.

Using the Southwire VD calculator, the longer the run the higher your lowest dimming level has to be.

Drive 25 fixtures @ 50% (5V) pull a pair of 14's and distance can be 530 feet with 3% VD.
If you want to dim down to 30% (3V) it's 318 feet.
20% dimming = 212 feet.
10% dimming = 106 feet. But see below*

Assumption: Fixtures are IEC60929 compliant, each fixture draws max 2mA to drive the dimmer. 
25 fixtures x .002A = 50mA total load on the dimming circuit.

You'll need a dimmer with enough available current to drive all the fixtures you want on that dimmer. 

*Note: It's my experience that 15% is about the lowest most manufacturer's lights will dim down to. 
That experience comes from lighting manufacturers sending me their fixtures to develop dimming enabled timers for them. We set up a test and see how far we can take it. Most of them have a limit pretty close to 1.35V. Drive less than that and the fixture goes to 100%. Also, drive 0V and it goes to 100% because it assumes the dimming function is not connected/ unused.

Another consideration - if you set up a light meter while doing the testing, 2V does not equal exactly 20%, 4V does not equal exactly 40%, etc., but it's pretty close.


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## LGLS (Nov 10, 2007)

MikeFL said:


> Thanks!
> 
> You inspired me to do some work on it.
> 
> ...


I wonder, if the 2 fixture circuits could be controlled by one dimming control, but when dimmer is OFF the lights should respond to the occupancy sensors?
Sort of a dim/direct switching control?


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## MikeFL (Apr 16, 2016)

If I had to do a gym with 4 entrances, I'd have occupancy sensors at each entrance plus some more strewn about. A group or person in the middle of the room shouldn't have to run to the door every time the occ sensor times out. Put them all in parallel.

Have one dimmer. If you enter via south entrance and dimmer is at north entrance, you walk in south entrance, lights come on at whatever dim level the last setting was. If you want it different, you walk to north entrance and set preferred dimming level.

If you can't find a dimmer with enough available current to drive all the fixtures, have multiple dimmers but install them adjacent each other at the same location. It would drive someone mad to have to run a lap around the room to set the light levels.


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## MikeFL (Apr 16, 2016)

LGLS said:


> I wonder, if the 2 fixture circuits could be controlled by one dimming control, ...


They are different circuits (power and dimming). So yes, it can be done.


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## Viggmundir (Sep 13, 2019)

wiz1997 said:


> On the drawing what does the 2 next to OS indicate?


The OS in the top little hallway area is just a PIR occupancy sensor. The 2 in the circle at the 5 in the big room is a note that they must be a combination dimming and occupancy sensing device.



wiz1997 said:


> Does the OS in the hallway control just the light in the hallway?


I would think so. None of the lights/switches on the plans are marked to indicate what controls them/what they control. The legend shows what should have been used, but it wasn't.



wiz1997 said:


> I'd also have to ask about the lighting on the ramps, landings and the stairs.


No additional lighting for those areas (except the stairs at the top, they go upstairs)



wiz1997 said:


> They may need more lighting according to any handicap accessibility requirements in your area.


This is the dimmer, occupancy sensor I have installed in our conference rooms.





Smart Sensor - Occupancy Sensor - Vacancy Sensor - ODD10-IDW


Smart Sensor, Passive Infrared, Antimicrobial, 0-10V Dimming, App configurable; Auto-ON/Auto-OFF or Manual-ON/Auto-OFF, neutral wire required, 120/208/220/230/240/277VAC, 50/60Hz; White. Wall plate sold separately.




www.leviton.com




1100ft2 coverage could be worth looking into some more.


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## Viggmundir (Sep 13, 2019)

LGLS said:


> Unless there’s another more detailed drawing, I’m not seeing what you’re seeing. I see an OS in a square at every door, 4 out of 5 doors also with a 2 in a circle. 2 in a circle means dimmer, for all the lighting, where are these dimmers?
> 
> Where are you seeing 3 OCs all at one end of the room? I see one at every exit/entrance only A space like this “Atrium” (college, school campus?) and this large is going to need ceiling mounted occupancy sensors, lest someone walking through be plunged into darkness 1/2 way through the space.
> 
> Seems the designer is using small executive conference room mentality applied to a massive all purpose public space setting.


2 in a circle means the occupancy sensors are a combination dimming/occupancy device. 

There are actually 6 entrances into this room. 1. Door top right, 2. door bottom middle, 3. door bottom left, 4. door middle left(what looks like a passageway just above these double doors is actually a serving window from kitchen area), 5. door upper left leads to an exit hallway and stairs to upstairs, 6. X mark on wall just to the right of the double remote head on the top wall is an archway leading to bathrooms. 4 sensors with a 2 in a circle, 1 without the 2 circle by the left kitchen door, I just realized I've been lumping this one as a 2 circle though.

The '3 all at one end of the room' are the 3 on the left side, yes one is not quite on the end wall but fairly close. I typed that line out before I thought to actually put a picture of the plan in, as a generalization that the sensor placement could be better. The far right side could have some coverage gaps.


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## Viggmundir (Sep 13, 2019)

MikeFL said:


> If I had to do a gym with 4 entrances, I'd have occupancy sensors at each entrance plus some more strewn about. A group or person in the middle of the room shouldn't have to run to the door every time the occ sensor times out. Put them all in parallel.
> 
> Have one dimmer. If you enter via south entrance and dimmer is at north entrance, you walk in south entrance, lights come on at whatever dim level the last setting was. If you want it different, you walk to north entrance and set preferred dimming level.
> 
> If you can't find a dimmer with enough available current to drive all the fixtures, have multiple dimmers but install them adjacent each other at the same location. It would drive someone mad to have to run a lap around the room to set the light levels.


It would drive me mad to run around and dim the room in sections, that's why I thought this was a strange way to do it. 
I agree with you about having one dimming location, and parallel occupancy sensors to keep the lights on. That would make sense. 

I was caught in thinking that the dimmers were not so much for manual level dimming, but more so for automatic dimming for energy codes based on daylight levels or occupancy levels. That's how the outside light fixtures are, they dim when no one is around, and brighten when you come closer at night time.

I tend to do more service work, and haven't done a new build on an assembly occupation before, so thought I would ask here and see what I was missing.


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## LGLS (Nov 10, 2007)

Viggmundir said:


> It would drive me mad to run around and dim the room in sections, that's why I thought this was a strange way to do it.
> I agree with you about having one dimming location, and parallel occupancy sensors to keep the lights on. That would make sense.
> 
> I was caught in thinking that the dimmers were not so much for manual level dimming, but more so for automatic dimming for energy codes based on daylight levels or occupancy levels. That's how the outside light fixtures are, they dim when no one is around, and brighten when you come closer at night time.
> ...


There’s got to be some central panel for lighting controls that all of the dimmer/ OC controls / light sensors and the 0-10v dimming fixture leads connect to. If this really is going to operate as a system with generic components, then paralleling the wall switch/sensors is about all you can do - ceiling mounted ambient light sensors would have to be used in order to zone control specific fixtures to different light levels, but since you said the room has no windows what would be the point?

Somewhere in the drawings and schedules there’s got to be some type of make and model numbers for all of these specific components, and I would check the equipment schedule in the electrical closets. Who knows maybe the entire building is controlled by one central BMS system?


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## splatz (May 23, 2015)

MikeFL said:


> Question: How far can you run on that 0-10V line, and how many fixtures can you drive with it?
> When I get asked I tell them you need one control per fixture or per post (in a parking lot) where you may have 4 fixtures on a post.
> I tell them you can't drive 0-10V dimming of an entire 45 acre shopping center off one 0-10V dimmer in the electric room, because it's going to have VD and inconsistent dimming levels.
> 
> ...


Absolutely, 0-10V dimming is subject to voltage drop like everything else. The load is tiny, which helps tremendously, but you'd have to know the actual amperage of the dimming circuit (not the lighting circuit) to calculate the voltage drop. Not all 0-10V dimming will be the same. 

You can reduce voltage drop by bumping up the wire size, bumping from 18 awg to 12 awg will get you much, much further. So you would want to look at the cost to maintain and install separate dimmers versus the bigger wire.


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## splatz (May 23, 2015)

I think you'll want your sensors placed according to the ambient light levels in the space. If the ambient light levels were all uniform, you'd just need one sensor, big open space like that you could put one in the center of the room for the whole thing, but it would dim the lights near the window to the same level as the lights back far from the natural light. The lighting in the space would be very uneven. If you divided it up with one dimmer on the first row by the windows, another the second row, etc., you'll get nice even combined light (ambient / natural plus lighting) through the space. 

If you want minimal distortion of the 0-10V dimming from voltage drop, you could start from one light and branch out in both directions, rather than starting at one end or the other, but I doubt that's going to make much difference in a room this size with 16awg or 18awg for the dimming.


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## 134sparky (Feb 27, 2014)

I've never seen wall mount sensor/switch by doors called out for a room this large, only private offices. I'd be worried about the lights turning off because of dead spots. 

Seems there should be at least some additional stand alone wall sensors scattered throughout, ceiling mount sensors and separate switches, or a combo of some wall mount and ceiling mount. 

I would assume without further info that they want ALL the lights to turn on when someone enters the room(separate zones seems stupid, its not that big of a room), stay on when someone is in there no matter where they are at and how little they move, be able to dim from the spots indicated, turn off automatically after everyone leaves. So I guess I would bid it for that...but I don't do bids just work haha so I might not know what I'm talking about.


Lutron wireless Pico switches, wireless sensors coupled with 0-10 power paks in the ceiling would make this job a breeze. All the wires would be in the ceiling, no need to bring anything down the walls. https://www.lutron.com/TechnicalDocumentLibrary/3683197.pdf


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## Slay301 (Apr 23, 2018)

Honestly just get a N-light system by acuity


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## 134sparky (Feb 27, 2014)

Slay301 said:


> Honestly just get a N-light system by acuity


Yeah n-light has wireless and also low voltage. With the low voltage you just need to daisy chain a cat 5 between all the sensors, switches, and power packs. The only thing that gets line voltage is the power pack. Switches and sensors only get cat 5. With both n-light and lutron you can manually program by pushing a series of buttons on the device to make them do what you want...1 min off or 45 min off, zone different sensors to specific lights, stuff like that. Basically anything the owner wants to do.

The advantage of the lutron wireless is that you can easily add more sensors down the road if what they spec on the print ends up not working the way the owner wants. They also add a wireless daylight harvest sensor that will dim some or all of the lights according to how much natural light is in the space.


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## Viggmundir (Sep 13, 2019)

LGLS said:


> There’s got to be some central panel for lighting controls that all of the dimmer/ OC controls / light sensors and the 0-10v dimming fixture leads connect to. If this really is going to operate as a system with generic components, then paralleling the wall switch/sensors is about all you can do - ceiling mounted ambient light sensors would have to be used in order to zone control specific fixtures to different light levels, but since you said the room has no windows what would be the point?
> 
> Somewhere in the drawings and schedules there’s got to be some type of make and model numbers for all of these specific components, and I would check the equipment schedule in the electrical closets. Who knows maybe the entire building is controlled by one central BMS system?


No central lighting panel. The only info in the specs, is model #'s for acceptable dimmers, but nothing for these combination dimming occupancy switches.


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## LGLS (Nov 10, 2007)

Viggmundir said:


> No central lighting panel. The only info in the specs, is model #'s for acceptable dimmers, but nothing for these combination dimming occupancy switches.


Then if I were you, I would send an RFI requesting the details with the caveat that the drawings are severely lacking in engineering, and that you would need an extra just to engineer the system they plan on putting in. You’ve already spent too much time on this, and time is money. Because if there were no other details shown or given or provided then you have posted here, then it is clear that the designer/architect is leaning on you to make all of the parts they’ve specified work somehow.

Maybe your RFI can suggest that n- light system mentioned above as an alternative to what the prints specify.


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