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My Bright Idea ran into a small snag. (Mounting some light fixtures)

penright

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I know I wanted LED lights, my first thought was 4 light 4 foot troffers converted to direct wire LED. Then I thought why not use normal sized screw in bulbs. For the same power usage I could spread them around. My challenge was in fixtures. I wanted the old barn style, you talking average $45 each. I found these at HD for $8. I am using EMT and 4" square boxes. So begins my delima. First let see if I can show a picture and explain the issues.

1. I had to use an octagon box to fit the holes. After I bought the fixtures, the hole for the wire is outside of the box.
1736432504937.png
I assume if I drill a hole in the middle, then I would be messing up the UL. Is this why they are so cheap? How should I fix it. Here is the instructions online (click here for instructions). I think they were expecting a gap in sheetrock and the ridge to give a gap for the wire to go into the center of the box. This does not seem right since now you have paper exposed to possible sparks.

2. Looking at the same picture, you can see that it has a ridge that is blocking my 3/4 EMT. I am guessing, I will need to go back to my 4" box with a mud ring to get the depth.

3. How my wires can I have in 3/4 conduit. I was not following the tables when I google it. I have seen discussions where it talks about circuit vs number of wires. I am pulling #12 and the breaker is 20 amp. Here is a overhead view of the lights.
{Picture was removed}
The square at the top is breaker box and at the bottom is switches. The elevation view would have the front (top) on a perlin (running left to right), the middle row in the peak, the back row is where the garage doors are, so I need to mount them on the garage doors tracks.
So I would like to control each row with independently. Most of the time it would be the peak if I just going in for something, then the front row. I could only see the back row on if I needed to work beside a car. So in one conduit I would need the power, then each switch leg for each row. How do you read the conduit fill charts? Do I need to run more than one conduit? How do I fixed that?
 
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ard

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That mounting bracket you are holding...

Screw that to the 4" octagonal box, using the screws in the box, fed through the elongated mounting slot- then slide it all the way over to the side...will the wires from the fixture now enter the box?

On the lights themselves..this is NINE SINGLE LED BULBS for the whole space? How many lumens? Have you tested how much illumination you will get?

You have no issues with wire fill....
 
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penright

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That mounting bracket you are holding...
Screw that to the 4" octagonal box, using the screws in the box, fed through the elongated mounting slot- then slide it all the way over to the side.
Sorry still not following... This is what I am hearing ...
1736432682477.png

I don't see how it slides or how I can mount it that way.


On the lights themselves..this is NINE SINGLE LED BULBS for the whole space? How many lumens?
The lights are 1500 lumens at 14 watts. Thats little over 100 lumens per watt, but the CRI is only at 80 :-( I went with the whiter 5000k.



Have you tested how much illumination you will get
Nope, just a guess. If the 9 is not enough, I can add some more rows, but for now the space is 720 sq feet, so each bulb is about 80, so that would be a 10 x 8 or small bedroom. By the time light goes through the frosted and the height, may need more. Right now I have two cheap 2 bulb 4 foot florescent temporary mounted to the trusses. Still organizing from the move, stuff is stack and spread out over the floor. Those lights positions are casting bad shadows. I am hoping the spread out will help that.
I called it a bright idea, not a good one. :headscrat
My pastor and I are in our mid 50's, like he said, if I can't see, I move my glasses up, down, if I still can't see, I add more light.:)


You have no issues with wire fill....
Cool. I was counting 9 wires. (1 ground,2 power,6 switch legs). While I have the power there I may add an outlet on that wall, for the drive in front of the building. Maybe vacuuming or something. Also, I was going around with the gurt and running into making corners. I can pull that and bring from my middle row down.
Looking at this chart ....
conduit-fill-chart.png

I can have 16? Is that physically possible? Does the ground count? This chart did not talk, but in my research there was talk about derating...?
 
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AffableCurmudgeon

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Why do you have a ground wire in EMT? Why not use EMT as ground?

For the off centered fixture hole, can you use 3/4 clamp connectors on the side of the box and feed the fixture wires through it? You can seal the fixture hole with some fire caulk if you like...
 
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penright

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Why do you have a ground wire in EMT? Why not use EMT as ground?

There was a thread on this ... My understanding, if you don't pull a ground, then you can use the EMT. But there are advantages to having a ground. My reason, I bought green wire before before I knew.


For the off centered fixture hole, can you use 3/4 clamp connectors on the side of the box and feed the fixture wires through it?
I just thought it is strange. I am tempted to drill a hole in the center or close enough to come inside. I keep think there is something I am missing. That is why I wanted to ask professionals how they would handled it.
 

Lassen Forge

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Speaking of LED lights - We wanted to try them, got the direct replacement ones for our 4 foot tubes, and they've been in service for a couple months... they've started either running dim or not coming on now. If this is representative of them, Im glad I didn't jump in whole hog... My T5's and T8's never did this - sure, they'd get the dark band and start to get dimmer, but not working or giving me half light after 3 months?
 

Stuart in MN

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I looked at the instructions - the drawing in there appears to show the wires coming up through the middle of the fixture so they would be inside the box, but from what I can see in your picture that doesn't agree with the real thing. Can you post a top view picture of the fixture so we can get a better view of how the wires are exiting it?
 

tyme2par4

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Sorry still not following... This is what I am hearing ...


I don't see how it slides or how I can mount it that way.

That's how the bracket should be. There should be 2 Keyhole shaped holes on top of the fixture. Those allow you to mount using the two longer screws on the bracket.
Can we get a picture from the top of the fixture?
 
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penright

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I looked at the instructions - the drawing in there appears to show the wires coming up through the middle of the fixture so they would be inside the box, but from what I can see in your picture that doesn't agree with the real thing.
I think the manufacture messed up, that's why they are $8 each. I think normally you would have the ceiling that the ring part would tighten up to. That would give a gap that the wire would fit through. Because I am mounting up to the box, I don't have that gap. I thought drill hole would be the answer, but I also know technically it would void the UL, so I thought I would ask. @Ashamsi already voted for new hole.
 

ard

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Yeah, I thought that strap was a bit longer, to allow some adjustment along the slots.

The hole seems like it has a finish to it? To prevent wire chafing?

In terms of 'voiding UL- what makes you think THAT is UL complaint? Wouldnt be the first Chinese POS with questionable stickers.

Oh, you could drill two new holes FOR THE SCREWS, such that the wire is now positioned in the box. Not re-routing wires, just shanging a screw hole- or two.
 

ard

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Oh, FWIW:


1-12%20Deep%20Bracket%20Boxes.jpg
 

Stuart in MN

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I think I'd drill a new hole. Chances are UL isn't going to make a surprise inspection. :) Just make sure to use a grommet or something so the wires don't chafe.
 
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penright

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Oh, you could drill two new holes FOR THE SCREWS, such that the wire is now positioned in the box. Not re-routing wires, just shanging a screw hole- or two.
Now that's thought.




The hole seems like it has a finish to it? To prevent wire chafing?
I bet it was just stamp, but that does give it a curved appearance. There is always black tape, and I have some tubing. I figured I could move the hole where the protective cloth would still work.

Here is a close up screwed to the perlin.
1736432830545.png

It's kind of hard to tell, but I don't think I have enough clearance for my EMT. I was thinking about getting a Octagon Extension Ring for more room.
 
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penright

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Summer was real busy, did not work on the garage any. Long story, but I am back tinkering. And back to the light issue. Kind of a update before I get to my question. I got the mounting figured out. I mounted the box as in the picture to the perlin. Then I added a box extension to lower it enough for all to fit. The shop is divided into 3 sections each about a car width each from what I am calling side to side. So I am putting one in front, middle, and back in each section. That makes a total of 9 lights.
My questions will reference this diagram.

LightPlan_zpsgjyoqwug.png


The top is back of the shop and bottom is front.
The rectangle at the very top is the breaker box. Conduit runs from it to the square box top light row. Then it makes it over to the top left. From there runs toward the back. From the back left down to two 4 square boxes.
I will measure when I get home but I believe they are 21 cui.

I have two basic questions, One has to do with neutrals and the second has to do with fill capacities. For example the ground (green) can be just one wire. The red is power and neutral from the breaker box. Inside the two boxes one with be power outlet (hey power is there). Then it (red) will be the hot for 3 switch legs. (may not be right terminology). As you can see orange will be the lights across the front and front left (right by the door). Then blue will be the middle lights with purple being the back two.

So that is my three switches (switch legs).
1. So do I have to run a neutral for each switch leg? My guess is yes for balance power.
2. The extender that I am putting on the box, do I get to add it's CUI?
3. Am I looking at the chart right, 3/4" EMT #12 can handle 17 wires?
4. Are my questions clear as mud? :eyecrazy:

The one I worried about is box with the front switch. That has 9 wires and 2 yokes. So 13 x 2.25 is 29.25 CUI. Can I add a box extension to make it right?
 
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penright

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Time to put the bow on it. :) It only took 7 years. Many other projects were needed for the organization, to clean up bay 2 so I could get a ladder over there. Now all the lights are finished. I also updated previous pictures on this thread since they were on Photobucket. I added a couple of more lights in bays 1 and 2 I put a light on every purlin. I discovered a flaw, with overhead doors open, they would block the lights. I added one in the middle below the doors to kind of help. Also, excuse the gutters. My neighbor enclosed their patio and had to redo theirs. My house does not have gutters all around and those matched what I do have. I will be installing them this spring to protect a flower bed that I am doing at the same time. :) Currently, there is a total of 15 lights counting the 2 over the work bench. They are 13w led with 100w equivalence. Right now I am using what would be the equivalent of 2 old 100-watt bulbs. The light is not too bad.


One other change I might make. Change the 2 that is in the center to a porcelain fixture and use one of the led that screw into it. Of course that would add another 160w, subtracting the 2 13w, that leaves a total of 500w. Still not bad. A side benefit is I would have two globs for when I drop one when changing the bulbs. :) Maybe just one would be enough. :)


Just an example ...
1736434476282.png
 
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