Dimming LED high bays...electrical newbie

[KPack]

I'm looking at using Lithonia CPHB LEDs in my shop. Probably 12K or 14K lumens. Shop is split into two equal areas of 36'x'36x14'. I plan to use either 6 or 9 (2 or 3 rows of three) in each room. Lithonia CPHB

These lights come with purple and gray wires for dimming. My questions is do I need to use these wires for dimming? Or is there a switch option that will control the voltage to the lights without having to run additional wires?

Second question, if I do have to run the wires, how are most guys doing this? I'll be using MC in the attic space, then dropping down to connect into the lights. Do the purple and gray wires need to be run in conduit or do most people just staple it along the framing? I'd rather not run conduit up there if I can avoid it.

I'm new to all this. Just want to make sure I'm doing it right.

 

[cybrdyke]

Yes, you need to use those purple and gray wires for dimming. The fixture doesn't have an alternate way to dim.
Most people do it the hard way. I dont know why. They run power to the fixture either with romex or MC cable and then run the dimming wires separately to a wallbox dimmer. The dimming wires are low voltage DC and so they dont need to be run in conduit. If you decide to use conduit for power and dimming, both sets of wires need to have the same insulation rating per NEC.
You can get MC cable with the purple and gray built into it. Your local electrical supply store probably has it in stock. It's called "luminaire cable", but it has a bunch of other lingo names. You can connect that cable to the fixture and then run it to the wallbox controller, like a Cooper SF10P, that has both power and dimming in one device. Pretty cool.
But the easiest way, especially if you are only using 9 of those fixtures is to get a Lutron Vive Powpak RMJS-8T-DV-B. All your power and dimming wires meet here in the ceiling. Then you use Lutron wireless switches called "Pico". You can wall mount them wherever you want. There are also wireless sensors for occupancy and daylight harvesting. By far the easiest installation of those fixtures.
Good luck,
CD

 

[dave*99]

And there is this too:

 

[sticktime]

Im interested in this as well. If using the Romex PCS, what type of dimmer needs to be utilized? Do you just surface mount that Vive Powpak RMJS-8T-DV-B next to the switch or is there a residential dimmer that will work?

 

[cybrdyke]

Im interested in this as well. If using the Romex PCS, what type of dimmer needs to be utilized? Do you just surface mount that Vive Powpak RMJS-8T-DV-B next to the switch or is there a residential dimmer that will work?

If you are going to use the romex and run it all the way from the LED fixture to the wallbox switch, then use the Cooper SF10P or similar that has both switching on/off and also dimming in one device.

If you are going to use the Vive Powpak, it gets mounted in the ceiling, onto the junction box that contains the power wires from the breaker and branch out to the fixtures. You would use regular romex between the breaker and junction box (as usual) and then either use the PCS romex or regular romex + 2-16AWG wires from the junction box to the fixtures. Then you use the Lutron Pico remote switches, which are wireless, to control the lights.

CD

 

[KPack]

Great information, thank you all. I'm running EMT in my walls and not Romex. But was planning on using MC in the attic space to wire the lights due to simplicity.

I've read elsewhere that if the signal wires are in the same junction box as the power wires that they have to have the same rated sheathing. The signal wires are inside the light, as are the power wires...essentially making the light a junction box. So I would need to sheath the signal wires?

Also, the MC will run directly into the lights, which will be hanging from a flat ceiling. If the signal wires are separate from the MC, and don't need to be in sheathing, do most people just run them out of the light bare? I'd like it to be as clean as possible so I'm leaning towards the MC with signal wires inside.

 

[sticktime]

Awesome thank you for that! i don't need the complication of the wireless remote so I'll just run the romex/dimmer wire to the switch you recommended

 

[dave*99]

Great information, thank you all. I'm running EMT in my walls and not Romex. But was planning on using MC in the attic space to wire the lights due to simplicity.

I've read elsewhere that if the signal wires are in the same junction box as the power wires that they have to have the same rated sheathing. The signal wires are inside the light, as are the power wires...essentially making the light a junction box. So I would need to sheath the signal wires?

Also, the MC will run directly into the lights, which will be hanging from a flat ceiling. If the signal wires are separate from the MC, and don't need to be in sheathing, do most people just run them out of the light bare? I'd like it to be as clean as possible so I'm leaning towards the MC with signal wires inside.

Let's break out the terms like this: SHEATHING is in this case the sheath around the Romex, or the MC sheathing or a Conduit.
If you have Class one wiring in a sheath (Carrying the 120V power) Then you need all the conductors in the SHEATH to be INSULATED appropriately for that Class.

So the INSULATION on the wire has to be rated for typically 600V. You can't put bell wire inside the same conduit as the power conductors and then run 120V on the 600V insulated wire and 0-10V on the bell wire. This is because bell wire is not rated for 600V and it would be in the same conduit as conductors carrying 120V. But you could for example, pull 600V rated wire through the conduit (THHN or THWN) and put 120 on some conductors and 0-10V on some.

The MC and Romex options already have 600V insulation on all conductors in the sheath.

As for your light housing, you can exit the housing with power in one sheath and exit separately with low voltage (Class 2) insulation on the wiring. Separate sheaths in this case.

 

[mike93lx]

The dimmers are 0-10V, not line voltage

 

[KPack]

Let's break out the terms like this: SHEATHING is in this case the sheath around the Romex, or the MC sheathing or a Conduit.
If you have Class one wiring in a sheath (Carrying the 120V power) Then you need all the conductors in the SHEATH to be INSULATED appropriately for that Class.

So the INSULATION on the wire has to be rated for typically 600V. You can't put bell wire inside the same conduit as the power conductors and then run 120V on the 600V insulated wire and 0-10V on the bell wire.

The MC and Romex options already have 600V insulation on all conductors in the sheath.

As for your light housing, you can exit the housing with power in one sheath and exit separately with low voltage (Class 2) insulation on the wiring. Separate sheaths in this case.

That clears it up, thank you. My confusion was in whether or not the sheathing was rated for 600 volts vs. the insulation. Thanks for helping me out.

 

[Shovelhead]

get a Lutron Vive Powpak RMJS-8T-DV-B. All your power and dimming wires meet here in the ceiling. Then you use Lutron wireless switches called "Pico". You can wall mount them wherever you want. There are also wireless sensors for occupancy and daylight harvesting. By far the easiest installation of those fixtures.
Good luck,
CD

excuse me for butting in KPack. Maybe I should start another thread.

CD, that fancy Powpak box sounds pretty neat. Pretty expensive too. Wonder about the reliability and longevity of that thing compared to standard hardwired switches/dimmers. ??

What other components are required for that box to hold hands with motion detection?
What the heck does occupancy and daylight harvesting mean?

I suspect that if used for motion detection, since it's wired to the shop lights in this case, all of those lights would come on?
Couldn't make it talk to a separate single wall or ceiling light?
If so would it have to be on the same circuit as the shop lights?

Nearly space age **** to me.. LOL

 

[billconner]

You can zone the fixtures, individually or groups, just more low voltage wires. So, yes, one light upon motion detection and switch rest, but then you forget those, so just put them all on occupancy/vacancy detectors, or maybe 2 zones.

Daylight harvesting simply reads daylight and dims fixtures so illumination is same level regardless of daylight.

Someday will have to see if POE lighting is adequate for garages - all wiring are RJ45 cords.

 

[cybrdyke]

excuse me for butting in KPack. Maybe I should start another thread.

CD, that fancy Powpak box sounds pretty neat. Pretty expensive too. Wonder about the reliability and longevity of that thing compared to standard hardwired switches/dimmers. ??

What other components are required for that box to hold hands with motion detection?
What the heck does occupancy and daylight harvesting mean?

I suspect that if used for motion detection, since it's wired to the shop lights in this case, all of those lights would come on?
Couldn't make it talk to a separate single wall or ceiling light?
If so would it have to be on the same circuit as the shop lights?

Nearly space age **** to me.. LOL

shovelhead,
$150 isn't expensive compared to time and materials running wires all over the space. As for reliability, Lutron is the largest dimming company in the industry and the Vive has been around for years. Millions have been sold and used by lighting pros, so dont worry about that.
The benefit of the Vive powpak is that you only have to run all your purple and gray control wires a few feet from the fixtures to the powpak. Your wall switches, occupancy sensors, daylight sensors are all wireless. You can put them wherever you want them and you can use as many of them as you want.
So, for instance, if you have 2 man doors and a garage door, you can stick wall switches on the wall next to the doors and a sensor on the ceiling for motion. Put one by the workbench, keep one in your toolbox, give one to the wife, etc. The wall switches are called PICO by Lutron and they cost about $25 each. The sensors are about $50 each. There is no wiring.
Occupancy sensor is another name for motion sensor. Same thing.
Daylight harvesting is when the ambient light from the sun is measured by a sensor and the lights are automatically dimmed back. This is an energy saving method that alot of commercial buildings use. Walmart is the best example.
If you had more than one Vive powpak, you can start to create different zones and control individual fixtures. But now you'd be getting expensive.
I know it seems space age, but it's been around for a long time and it's pretty common stuff.

CD

 

[Shovelhead]

Thanks CD. Appreciate the info.
Common stuff to some I suppose, but not this boy.
Gives me something else to study on a cold rainy day.

 

[pbon]

We are adding dimming to 12 LED high bays mounted in a gym ceiling (0-10v dimmer capable but purple and gray wires not connected when lights installed). It does not seem like that much more work to just add the dimmer switch wiring given the amount of 0-10V wiring that will be run to connect the lights. If you told me I could save $300 with the fancy electronic module and matching switch instead of spending a few more hours to just run the wring to a dimmer switch, that would not sway me. But I can see how there could be applications where there are not so many lights and the wiring would be a lot of trouble to run.

 

[cybrdyke]

We are adding dimming to 12 LED high bays mounted in a gym ceiling (0-10v dimmer capable but purple and gray wires not connected when lights installed). It does not seem like that much more work to just add the dimmer switch wiring given the amount of 0-10V wiring that will be run to connect the lights. If you told me I could save $300 with the fancy electronic module and matching switch instead of spending a few more hours to just run the wring to a dimmer switch, that would not sway me. But I can see how there could be applications where there are not so many lights and the wiring would be a lot of trouble to run.

It's also not always about how hard it is to run wires, sometimes it's about where you are going to run the wires to. If you have ceilings that you cant get into, if you have block walls or insulated walls that you cant fish wires down, or if there's multiple locations that you want to install switches, then you'd save considerable time and materials going wireless. I guess it just comes down to how much your time and effort are worth. Some of us will choose the faster way and spend a few more bucks to do it. Others have all day to **** around pulling wires and trying to figure out how to wire 4-way switches. To each his own.
CD

 

[KPack]

I've been doing some more thinking and research of my options and am leaning more towards Lutron's wireless solution. My local electrical supply does not have the MC luminary cable, so I'm trying to figure out how to do what I need with normal MC.

The shop has two identical spaces....36x36 in the front and 36x36 in the back. I plan to use 9 of Lithonia's CPHB 15k lumen lights in each room. Equally spaced gives me 100fc in most areas of the rooms. Each room has two entry points...one at an outside man door, and one at a central double door on a dividing wall between the two spaces.

I was considering having two zones in each room, so I wouldn't have to have all the lights on at once if I didn't want to. Normal wall-mount switches with 0-10V dimming are pricey at ~$50 each. If I'm thinking of it right, I would need 4 in each room...2 by each door. At that point I might as well just use the Vive Powpak and some Picos.

i would still need to run MC to power all the lights, but if I could just run the dimming wires separate (without any sheathing? Just staple to the wood??) to the Powpak it would definitely simplify it. Of course I would need two Powpaks....one for each room.

Am I thinking of all this correctly?

**Edit - now I'm reading that the Vive Powpaks have limits on how much they can power. The highest one I found was something like 8 amp draw max. That won't work because the lights I'm using draw about 1 amp each (I think that's right). So maybe I'm back to the luminary wire...

 

[dave*99]

Following....

 

[billconner]

It seems to me the more devices the more failure points. Lived in houses with 100 year old wiring and spat switches and still worked fine. I have some reservations that modules and devices will work as flawlessly for as long.

 

[mike93lx]

It seems to me the more devices the more failure points. Lived in houses with 100 year old wiring and spat switches and still worked fine. I have some reservations that modules and devices will work as flawlessly for as long.

I have no intention of living that long so tech is good for me!

 

[cybrdyke]

The shop has two identical spaces....36x36 in the front and 36x36 in the back. I plan to use 9 of Lithonia's CPHB 15k lumen lights in each room. Equally spaced gives me 100fc in most areas of the rooms. How did you come to that conclusion? It sounds wrong. Each room has two entry points...one at an outside man door, and one at a central double door on a dividing wall between the two spaces.

I was considering having two zones in each room, so I wouldn't have to have all the lights on at once if I didn't want to. Normal wall-mount switches with 0-10V dimming are pricey at ~$50 each. If I'm thinking of it right, I would need 4 in each room...2 by each door. At that point I might as well just use the Vive Powpak and some Picos.

i would still need to run MC to power all the lights, but if I could just run the dimming wires separate (without any sheathing? Just staple to the wood??) to the Powpak it would definitely simplify it. Of course I would need two Powpaks....one for each room.

Am I thinking of all this correctly?

**Edit - now I'm reading that the Vive Powpaks have limits on how much they can power. The highest one I found was something like 8 amp draw max. That won't work because the lights I'm using draw about 1 amp each (I think that's right). So maybe I'm back to the luminary wire...

For your 88w fixtures x 9 of them, you would need 1 Powpak. The powpak only does one "zone". If your interest is having two zones so that you dont have all the lights on, then you'll need 2 Powpaks. You'll also need to add another Pico. Another option without having two Powpaks is to consider having all the lights on, but at 50% output. I know it's not exactly the same, but it's an option. I mean, you're going to the trouble of connecting the dimming function...so USE it. Also, if you want to add in any sensors, you just stick them on the wall. Great for running in to the space, grabbing a wrench and leaving.
Plan B would be to run power wires and control wires across the ceiling, down the wall to 3-way wallbox switches, which as you've found out, are also pricey. With this set up, all you can do is on/off/dim, which might be all you need. You would need 2 at each door of each space, so 8 total.
Plan C would be to forget about the dimming function and just use cheap 3 way and 4 way switches to create as many zones as you want. Apparently, these will work flawlessly for over 100 years!
Keep asking questions!
CD

 

[Toomanytools?]

Hey KPack . I have a similar light as yours 14,400L/ 5000K. My RV shop is 36x56x16 the "Visual Lighting Calculator" suggested 18 for that light with 104FC. I also ran the CPHB 15000LM HEF GCL MD 50K 90CRI, with your shop specs and suggested 12 with 95FC. Take all that with a grain of salt so to speak. I hung up 2 of my lights and wow, I can't imagine 18. For me I think 6 would be fine but I may go with 8. Yours at 9 should be great. I'm just saying you may be surprised so having a dimming feature will be good.

 

[Shiftless]

(Following)

Question:
In a 36x36 space, if you have dimming capability, why would you want to further complicate things by separating into 2 zones so you didn’t have to have all 9 lights on at the same time?
If you want less light, just hit the dimmer. Am I missing something? I assume those big LED fixtures draw less current when dimmed so it‘s not an energy conservation move.

 

[Toomanytools?]

For your 88w fixtures x 9 of them, you would need 1 Powpak. The powpak only does one "zone". If your interest is having two zones so that you dont have all the lights on, then you'll need 2 Powpaks. You'll also need to add another Pico. Another option without having two Powpaks is to consider having all the lights on, but at 50% output. I know it's not exactly the same, but it's an option. I mean, you're going to the trouble of connecting the dimming function...so USE it. Also, if you want to add in any sensors, you just stick them on the wall. Great for running in to the space, grabbing a wrench and leaving.
Plan B would be to run power wires and control wires across the ceiling, down the wall to 3-way wallbox switches, which as you've found out, are also pricey. With this set up, all you can do is on/off/dim, which might be all you need. You would need 2 at each door of each space, so 8 total.
Plan C would be to forget about the dimming function and just use cheap 3 way and 4 way switches to create as many zones as you want. Apparently, these will work flawlessly for over 100 years!
Keep asking questions!
CD

Thanks Cybrdyke for this info. I had looked into Lutron wireless before but thought it was too costly and would have troubles with the wireless. Now though as I have some challenges running wire this looks like the way to go plus giving me the other sensor options.

 

[pbon]

For Plan B, don’t you have to run power and control wires across the ceiling? The control wires have to all get to the powpak, right? And if the power wire is not already in the ceiling and instead has to come up the wall, is it really that much harder to bring the wires back down the wall?

I understand that if you want a switch on every wall or are working in a 100+ year old house with plaster walls into which you would have to cut and patch 20 holes to run wires, the fancy switches and powpak make sense. When removing the remaining knob and tube from our former 130 year old house, we used a few Pico switches. I still had about 10 holes to cut and patch but it would have been more without the Picos.

 

[cybrdyke]

For Plan B, don’t you have to run power and control wires across the ceiling? The control wires have to all get to the powpak, right? And if the power wire is not already in the ceiling and instead has to come up the wall, is it really that much harder to bring the wires back down the wall?

I understand that if you want a switch on every wall or are working in a 100+ year old house with plaster walls into which you would have to cut and patch 20 holes to run wires, the fancy switches and powpak make sense. When removing the remaining knob and tube from our former 130 year old house, we used a few Pico switches. I still had about 10 holes to cut and patch but it would have been more without the Picos.

Hey Pbon,
Yeah, power and control wires have to go from the fixtures to the Powpak in the ceiling. Power wires would be run as normal. Control wires just the short distance from fixtures to Powpak. The point was that it's quite alot less than control wires going from fixtures to two different switches on one side of the space and then control wires going to two different switches on the other side of the space.
How hard is it to get wires down the wall? Depends on lots of things. Is it already boarded? Insulation? Steel or wood studs? etc.... Then wiring up 8 3-ways. For some folks who do wiring alot, might not take that much time. Others really struggle with it. You should see some of the threads on this forum covering 3-way switches! Like I said before, some folks have all day to play around and do this kind of stuff. Others dont. It just depends....
CD

 

[billconner]

Hey KPack . I have a similar light as yours 14,400L/ 5000K. My RV shop is 36x56x16 the "Visual Lighting Calculator" suggested 18 for that light with 104FC. I also ran the CPHB 15000LM HEF GCL MD 50K 90CRI, with your shop specs and suggested 12 with 95FC. Take all that with a grain of salt so to speak. I hung up 2 of my lights and wow, I can't imagine 18. For me I think 6 would be fine but I may go with 8. Yours at 9 should be great. I'm just saying you may be surprised so having a dimming feature will be good.

Where does the idea of 100 fc needed come from? Graduate degree in lighting design and 40+ years of experience designing lighting and 100 fc just seems extreme for all but the most detailed work. Not criticizing, just trying to understand the basis. Seems you found less than 100 fc adequate? I sure find well designed 50 fc very good and adequate for carpentry shop work. And is a task light so awful once in a while?

I'd still always try for more sources - even if smaller - to minimize shadows. I might have laid out the same number of fixtures or even more - but with lots of overlap and good glare cutoff - like maximum 60 degree beam cutoff - but lower outputs per fixture. I kind of wretch when I see those big spaces with a lot of fixtures and you can see the face or lamp of all of them from every place in the room. Lot easier to see and focus if there is not bright glare from a fixture across the room.

Not critical - just trying to grasp the different perceptions and backgrounds.

 

[cybrdyke]

Where does the idea of 100 fc needed come from? Graduate degree in lighting design and 40+ years of experience designing lighting and 100 fc just seems extreme for all but the most detailed work. Not criticizing, just trying to understand the basis. Seems you found less than 100 fc adequate? I sure find well designed 50 fc very good and adequate for carpentry shop work. And is a task light so awful once in a while?

I'd still always try for more sources - even if smaller - to minimize shadows. I might have laid out the same number of fixtures or even more - but with lots of overlap and good glare cutoff - like maximum 60 degree beam cutoff - but lower outputs per fixture. I kind of wretch when I see those big spaces with a lot of fixtures and you can see the face or lamp of all of them from every place in the room. Lot easier to see and focus if there is not bright glare from a fixture across the room.

Not critical - just trying to grasp the different perceptions and backgrounds.

There was a guy on the forum a while back who thought he knew alot about lighting and always recommended 93fc because that's what the IES says should be in a pro automotive shop. Everyone followed along and now it's what they think they should shoot for. You're correct. It's extreme overkill. Also alot of folks come here thinking that they can use lumens divided square foot to calculate fc levels. I do my best to squelch these urban legends. Imagine using 24,000 lumen highbays in a 12' ceiling because it's the only way you can get to 100fc. Geesh.
CD

 

[billconner]

12' ceiling and I'd like fixtures on 6' centers. Probably will give in some but the ratio is in the ballpark. But in all cases illuminance - footcandles - is just one aspect.

Thank you for the GJ history.

 

[Toomanytools?]

Where does the idea of 100 fc needed come from? Graduate degree in lighting design and 40+ years of experience designing lighting and 100 fc just seems extreme for all but the most detailed work. Not criticizing, just trying to understand the basis. Seems you found less than 100 fc adequate? I sure find well designed 50 fc very good and adequate for carpentry shop work. And is a task light so awful once in a while?

I'd still always try for more sources - even if smaller - to minimize shadows. I might have laid out the same number of fixtures or even more - but with lots of overlap and good glare cutoff - like maximum 60 degree beam cutoff - but lower outputs per fixture. I kind of wretch when I see those big spaces with a lot of fixtures and you can see the face or lamp of all of them from every place in the room. Lot easier to see and focus if there is not bright glare from a fixture across the room.

Not critical - just trying to grasp the different perceptions and backgrounds.

Hey Bill, Cybrdyke touched on it. The 100fc at table height 30-36" was tossed out there and many think that is the target for lighting. Not my recommendation, my point for the OP was that he may not need the 9 or 12 fixtures he had planned. It is the same thing with the dimmers I guess it is nice to have that flexibility, but I have never been in a commercial shop that had dimmers, zones or every other light, yes.

 

[ycgoat]

I am a master electrician and now electrical engineer for a hi profile location and thought I knew all i needed to know about lighting until I went to set up my new 2400 sq-ft building. I used some of the analysis software found on this forum, which gave me a warm and fuzzy on my lay out, but in the end I went with (12) $20, 5K lumen fixtures spacing close to what the software recommended but tweaked to match the framing members which are at ~5' on center. I tried to lay them so the fixtures were between the garage doors; for access later and to hopefully put the light where I needed it. This does not cover the entire 30'x80' building because one end will be a separate room leaving 30'x65'. I am hoping for ~50 ft candles/ft at a 3' work height. I will be putting in a work shop/bench area and will add decorative lighting there, otherwise I would have added 1 row of 3 fixtures.

 

[billconner]

ycgoat - You can test my remote design skills but I would estimate you are not at 50 fc, more like 20 to 30. I could be off. I started doing this while still using a slide rule in grad school, did graduate to a calculator, but never made it to the computer programs for this. I do usually draw it in AutoCAD (having never made it to Revit).

 

[KPack]

For your 88w fixtures x 9 of them, you would need 1 Powpak. The powpak only does one "zone". If your interest is having two zones so that you dont have all the lights on, then you'll need 2 Powpaks. You'll also need to add another Pico. Another option without having two Powpaks is to consider having all the lights on, but at 50% output. I know it's not exactly the same, but it's an option. I mean, you're going to the trouble of connecting the dimming function...so USE it. Also, if you want to add in any sensors, you just stick them on the wall. Great for running in to the space, grabbing a wrench and leaving.
Plan B would be to run power wires and control wires across the ceiling, down the wall to 3-way wallbox switches, which as you've found out, are also pricey. With this set up, all you can do is on/off/dim, which might be all you need. You would need 2 at each door of each space, so 8 total.
Plan C would be to forget about the dimming function and just use cheap 3 way and 4 way switches to create as many zones as you want. Apparently, these will work flawlessly for over 100 years!
Keep asking questions!
CD

Thanks, that's very helpful. Those were the options I was thinking of, so it's good to know I was not off in left field. Also good to know that a single Powpak will power 9 lights. I'll have to get two....one from the front room and one for the back.

Hey KPack . I have a similar light as yours 14,400L/ 5000K. My RV shop is 36x56x16 the "Visual Lighting Calculator" suggested 18 for that light with 104FC. I also ran the CPHB 15000LM HEF GCL MD 50K 90CRI, with your shop specs and suggested 12 with 95FC. Take all that with a grain of salt so to speak. I hung up 2 of my lights and wow, I can't imagine 18. For me I think 6 would be fine but I may go with 8. Yours at 9 should be great. I'm just saying you may be surprised so having a dimming feature will be good.

The lighting software I looked at (Acuity Brands I think) came back with 18 of the 15k lights (9 for the front room and 9 for the back) to get 100fc. It's what I was thinking of doing anyways, so it was good confirmation. I would much rather have it too bright and dim it back, than have it too dark and have to add more. I don't really want to go back and change things once I have the walls and ceiling buttoned up.

(Following)

Question:
In a 36x36 space, if you have dimming capability, why would you want to further complicate things by separating into 2 zones so you didn’t have to have all 9 lights on at the same time?
If you want less light, just hit the dimmer. Am I missing something? I assume those big LED fixtures draw less current when dimmed so it‘s not an energy conservation move.

Yes, now that I'm thinking through everything I'm leaning much more towards just doing a dimmer and not worrying about separate zones. Too much wiring and too complicated. I have very little time to devote to working on the shop with all of life's other demands, so at this point I'd like to keep things as simple as possible.

Where does the idea of 100 fc needed come from? Graduate degree in lighting design and 40+ years of experience designing lighting and 100 fc just seems extreme for all but the most detailed work. Not criticizing, just trying to understand the basis. Seems you found less than 100 fc adequate? I sure find well designed 50 fc very good and adequate for carpentry shop work. And is a task light so awful once in a while?

I'd still always try for more sources - even if smaller - to minimize shadows. I might have laid out the same number of fixtures or even more - but with lots of overlap and good glare cutoff - like maximum 60 degree beam cutoff - but lower outputs per fixture. I kind of wretch when I see those big spaces with a lot of fixtures and you can see the face or lamp of all of them from every place in the room. Lot easier to see and focus if there is not bright glare from a fixture across the room.

Not critical - just trying to grasp the different perceptions and backgrounds.

I don't know much about lighting, so I'm just using 100fc as a reference based on what other people have said, and what seems to have worked for them. I would much rather have too much light and dim it back, than not enough light and need to add more. The front half of the shop will be garage and workshop space. I do a lot of work on cars as a hobby....both maintenance and restoration. I hate not being able to see what I'm doing. Lots of light on the ceiling, finished drywall in a light color, and probably a lighter color on the floor, will hopefully help the light to reflect and bounce up so I can see easier under vehicles.

The back half of the shop will be game room/hobby room/etc that will require good lighting for the types of hobbies that will be back there. Again, I'd rather have too much light than not enough.

 

[ycgoat]

BillConner you may be right, not sure if I mis spoke or was just wrong in my estimates (I do not have my design here with me) but the quick search for online calculators seem to say 30 fc/ft for (12) 4', 5K Lumen fixtures at 12' in a 1950 sq-ft shop, but that 30 is still fine for a garage.

 

[billconner]

If you have a minimum of 30 fc everywhere, its a lot of light. The eye is amazing at adjusting. While in 30 fc I'd probably add a task light if
I was making pencil marks on wood and cutting all day, for a few cuts I's never miss it. Duration and glare and how shadowless the light is have as much to do with seeing and eyestrain as just illumination level.

 

[Shovelhead]

I was making pencil marks on wood and cutting all day, for a few cuts I's never miss it. Duration and glare and how shadowless the light is have as much to do with seeing and eyestrain as just illumination level.

VERY good points Mr. Conner.
That's my struggle right now laying out lighting for 16w x 30d - 10' ceiling woodshop.
Most all the layouts have the light rows 4' off each 30' wall.

Might be fine for my table saw in the center of the room but what about a miter saw right against the wall? Or a couple other main workbenches along the wall? Seems I'll have my own shadow cast over my miter bench and other benches.

Yeah, a man could add "task" lighting, but in a new shop I'm not 100% certain exactly where each tool will be other than the table saw. I'd like to light the sucker with 2 switches max for ceiling mounted lights rather than jack with "task lighting".

I see lighting a woodshop is not much different than lighting a shop that you'll be working on a carburetor on a bench most likely against a wall.

 

[billconner]

every layout is different but with work benches at the wall, you need to get near 2' from wall with 8' ceiling, so maybe 30" with 10', to avoid operator shadow, and you want every inch to be lit by 2 fixtures, imho. Lots of small sources rather than a few big ones ("jewel lighting" versus SFS as my grad school teacher said - the Ss being "single" and "source" - you can fill in "F" )

 

[rixtrix1]

Late to the party, but have a similar question about adding dimming to my 6 Lithonia CPHB 12k LED high bay lights. I ran a conventional switched 120v circuit with outlet receptacles in the ceiling where I installed my lights and am also using this same circuit to power a variable speed exhaust fan). I just plugged a pigtail from each fixture into the receptacle. I'm still confused after going through this thread about adding the dimming feature to the lights: does it replace the 120v supply the lights run on now or is another, low voltage circuit ran to the purple/gray wires in the fixture to power the dimming driver in addition to the 120v currently supplied? The overhead outlets are also used to power task or machine specific fixtures around the shop walls( 24x32x10) ).

I may be a complete dummy, but in looking at some Leviton dimmer/switches, it appears they have 3-120V input wires ( line, neutral and gnd) and 2 low voltage output wires, hence the questions above. If this is so, I already have another lighting circuit ran int the attic space from a double gang box with 120v power available in the box, so I could turn the now task lighting circuit off/on separately from the high bays? I've used pigtails in all my boxes rather than hook up any switches or receptacles directly.

 

[dave*99]

Late to the party, but have a similar question about adding dimming to my 6 Lithonia CPHB 12k LED high bay lights. I ran a conventional switched 120v circuit with outlet receptacles in the ceiling where I installed my lights and am also using this same circuit to power a variable speed exhaust fan). I just plugged a pigtail from each fixture into the receptacle. I'm still confused after going through this thread about adding the dimming feature to the lights: does it replace the 120v supply the lights run on now or is another, low voltage circuit ran to the purple/gray wires in the fixture to power the dimming driver in addition to the 120v currently supplied? The overhead outlets are also used to power task or machine specific fixtures around the shop walls( 24x32x10) ).

I may be a complete dummy, but in looking at some Leviton dimmer/switches, it appears they have 3-120V input wires ( line, neutral and gnd) and 2 low voltage output wires, hence the questions above. If this is so, I already have another lighting circuit ran int the attic space from a double gang box with 120v power available in the box, so I could turn the now task lighting circuit off/on separately from the high bays? I've used pigtails in all my boxes rather than hook up any switches or receptacles directly.

The Leviton

DS710-10Z​

Does not have a neutral wire. It does have provision to work in a 3 way circuit, hence the 2 reds and a black.

The dimmer has 2 functions. It switches the 120V power to the lights just like a normal switch. And it handles the 0-10V dimming function via the LV wires.

The lights will need 120V to light up, if you do not connect anything to the dimming terminals they will run at full brightness. Lights are not powered by the 0-10V terminals. They are controlled by that circuit.

 

[rixtrix1]

Thanks, Dave*99. So, 1-red and black for the 120V on-off function, green to gnd , then run the low voltage pink and purple to the dimmer wires at each fixture? The only other thing, will be is to find a dimmer switch able to handle the wattage of all the lights, which is just over 1500w total