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Gary Reif
11-28-2015, 10:22 PM
Can anyone tell me what the minimum recommended height is for a t8 two bulb four foot light fixture? I'm considering replacing the t12 light fixtures in my shop and the ceiling joists are 8 ft. My shop/garage is 24ft by 30ft and I'm considering installing 6 fixtures. Would this be to many to low? I do quite a bit of wood working but I also have my lathe and mill in it and like having plenty of light while working in there.
Thanks for any suggestions.
Gary

Duffy
11-28-2015, 10:47 PM
I would not change the fixtures, just change the bulbs. They ARE interchangeable. There is virtually no change in light output.

RichR
11-28-2015, 11:00 PM
Here's a technique I used when redoing the lighting in my garage and my parents basement. Take a fixture and wire a line cord to it.
Plug it in and hold it up in one corner of the area you wish to illuminate. Adjust the height and distance from the walls until you are
satisfied with the lighting in that one area. Mount a light fixture at that spot and energize it. Take the fixture with the line cord and
hold it up to light up another area. Adjust the distance until you get an even overlap of light from the first fixture. That will be the
spacing you want to use between fixtures. Since you are using tubes, you should determine spacing in the X and Y directions
separately.

firbikrhd1
11-29-2015, 09:54 AM
I am in the process of installing T-8s in my new shop (running wiring now), which is 25' X almost 18' with 9' ceilings. I am installing 6 tandem 8' fixtures (4- 4' T-8 tubes per fixture), end to end plus am additional 4' tandem on the end of each row for a total of three rows 20' long - 10 tubes per row, lengthwise. Outer rows will be 40" of each side wall with a little over 5' between outer rows and the center row. White ceilings and light colored walls will help light be reflected around to reduce shadows. I plan to use additional task lighting at machines or work areas as needed. This decision was made on the advice of my brother in law who is a licensed electrician that works in industrial settings.
The center row will be switched separately from the outer rows for times when I only need lighting to find my way through the shop to get something needed elsewhere.

Meaning no offense to Duffy, but I believe that although the tombstones will allow T-8s to fit in T-12 fixtures I believe the ballasts are different. T-8s do not suffer from the same issues that T-12s do in cold areas.

Some time in the future, when money isn't as tight, I may replace the T8s with LEDs. I saw LED replacements for T8 fixtures at the local big box home supply the other day. Maybe as time goes on they will be less expensive.
http://www.homedepot.com/p/Philips-InstantFit-4-ft-T8-32-Watt-Cool-White-4000K-Linear-LED-Light-Bulb-434605/205041684

They may be available to fit T12 fixtures as well.

Paul Alciatore
11-29-2015, 11:06 AM
I don't think you would have any problems due to the ceiling height.

I have six four-tube fixtures in my 20' x 20' garage with an 8' ceiling and it is OK, but sometimes I wish I had put more. You may want to consider 8, 9, or more fixtures.

J Tiers
11-29-2015, 11:10 AM
I would not change the fixtures, just change the bulbs. They ARE interchangeable. There is virtually no change in light output.

Interesting... I had thought they were deliberately made incompatible, to avoid having them used on old magnetic ballasts

Duffy
11-29-2015, 11:11 AM
No offense taken. I changed all my T12s for T8s a couple of years ago, and the ballasts work just fine. Now changing to LEDs is another matter. There are TWO different tubes; one is a simple drop-in replacement for a fluorescent tube, while the other requires that the ballast be removed and the LEDs hard-wired to the supply. This is a case of "pay me now or pay me later." In the first instance, when the ballast fails, either replace the ballast, OR replace the tube AND hard-wire the replacement. The second choice requires an electrician, (except of course for use multi-talented types :rolleyes:!) Remember, the LEDs will most probably outlast the ballasts, if we can believe the advertising, (and advertising NEVER lies!)

SteveF
11-29-2015, 11:48 AM
........... I'm considering installing 6 fixtures. ...............



If I read that right you are hanging 12 bulbs for 60 sq ft per bulb. I consider my shop to be well lit and I've got 25 sq ft per bulb.

I came up with that number by counting light fixtures and ceiling tiles in offices where I worked and retail outlets and that seem to be fairly consistent.

You can always add task lighting if your first try isn't enough.

Steve

gellfex
11-29-2015, 12:41 PM
COSTCO has had LED shoplight fixtures for under $35, competitive with all but the rock bottom T8 fixtures. I built my shop 18 years ago and the shoplites from then have been going bad over the last 5 years. I bought a couple as an experiment, was very happy and bought several more. They appear to have higher output than the T8's. I've even used them as jobsite lights vertically on a stand, and if they fall over or take a shot from a 2x4, no problem. Also no smoke like from sawdust landing on a halogen work light.

http://www.costco.com/4%E2%80%99-LED-Shop-Light-with-Pull-Chain,-2-pack.product.100223617.html

lakeside53
11-29-2015, 12:49 PM
You can "mechanically" put in T8 bulbs into most T12 (but there are two types of tombstone connections), but... the ballast should be changed - the current is too high and will lead to short bulb life. Old magnetic ballasts (and the first generation of low frequency electronic) suck below 40-50F. SOME (not all) electronic ballast work well to sub zero temps.

Personally... I'd gut them and put in Led replacement tubes that do not require any ballast, or, replace the entire fixture with Led.

darryl
11-29-2015, 12:52 PM
I tried a pair of T-8s in my old fixture, and while they did light at times it wasn't reliable. Probably if the ballast was electronic it would have been ok.

I haven't tried the led shoplight fixtures, but I did find some 60w led 'bulbs' cheap at walmart. Granted, that would require that you wire in a lot of standard sockets, but the light seems good and the price was right.

Axkiker
11-29-2015, 01:31 PM
So what do you all mean when you say "hard wire the LED ?" Do you mean directly to the AC ????

J Tiers
11-29-2015, 01:35 PM
No offense taken. I changed all my T12s for T8s a couple of years ago, and the ballasts work just fine. Now changing to LEDs is another matter. There are TWO different tubes; one is a simple drop-in replacement for a fluorescent tube, while the other requires that the ballast be removed and the LEDs hard-wired to the supply. This is a case of "pay me now or pay me later." In the first instance, when the ballast fails, either replace the ballast, OR replace the tube AND hard-wire the replacement. The second choice requires an electrician, (except of course for use multi-talented types :rolleyes:!) Remember, the LEDs will most probably outlast the ballasts, if we can believe the advertising, (and advertising NEVER lies!)

The ones I have seen that will tolerate the ballast (magnetic) still in place will also work fine direct, usually 120 to 277V without changes. The ability to work through the ballast is a convenience when switching over, and not a requirement. So there should be no reason to replace them if you take out the ballast.

Axkiker
11-29-2015, 01:40 PM
Also while we are on the topic of lighting is there a flush mount type fixture ? The garage ill be moving to at present just has open exposed rafters. I plan to drywall and maybe blow in insulation I figure this is probably the best first step to insulating it. Is there a flush mount lighting system ??? I "Might" add some sort of beam and trolly so I need to retain the most ceiling height I can.

Axkiker
11-29-2015, 01:52 PM
Okay, another question. Anyone toyed with the idea of retrofitting t8 or whatever type fixtures to use some of the newer strip led lighting you can buy by the foot. Not sure if its powerful enough yet but maybe an idea??

RussZHC
11-29-2015, 05:14 PM
Found a couple of items that fit with the discussion, http://www.lightingassociates.org/i/u/2127806/f/tech_sheets/FAQs_T8_or_T5-HO_-__Which_should_I_use_.pdf and https://www.youtube.com/watch?v=UQ7BIyEd89U

need to keep in mind that LED technology esp regarding costs is changing quite rapidly, so the video from 2011 as example is most likely quite dated.

https://www.youtube.com/watch?v=Zjw2UXVJaS0 fluorescent system to LED

Gary Reif
11-29-2015, 06:43 PM
Thanks for all of the replies. It's very handy to be able to tap into the knowledge of fellow Home Shop Machinists.
Gary

gellfex
11-29-2015, 07:16 PM
Okay, another question. Anyone toyed with the idea of retrofitting t8 or whatever type fixtures to use some of the newer strip led lighting you can buy by the foot. Not sure if its powerful enough yet but maybe an idea??

I've used it for undercabinet, but it's not that high output or efficient, 82 Lumens (1.5 Watts) per foot. Compare that to the Costco shoplite with 38w yielding 3700 Lumens @97 per Watt.

http://www.amazon.com/gp/product/B005GL5UG2?psc=1&redirect=true&ref_=oh_aui_search_detailpage

koda2
11-29-2015, 09:16 PM
Got this off of a U tube video a while back. Forgotten the author or I'd give him credit:

For ceiling lighting with 4 foot T8s. Draw out the ceiling dimensions in scale. Use a pencil line for the two bulb fixture.
Make no point on the line more than 4 feet from the wall or another light in any direction. Continue drawing lines until the ceiling space is filled.

I used 8 4ft two-bulb fixtures for a roughly 20 x 20 garage ceiling that was sheet rock and painted white. Excellent illumination throughout.

J Tiers
11-29-2015, 09:33 PM
Was at a Rural King store in Ohio a while back. they had LED instead of fluorescents. Looked like 6 foot or so between rows, rows went end to end, high bay building, lighting was very good

SteveF
11-30-2015, 07:44 AM
Also while we are on the topic of lighting is there a flush mount type fixture ? .............

The standard 4 tube 4' long fixture is designed to rest on a suspended ceiling track that is 24" on-center. So, if your trusses are 24" apart the fixture will fit between them. I just went and checked mine, they hang a little less than 1" down (the actual space is 22 1/2"), so with the 1/2" drywall it is very close to flush and you will need a small trim strip.

Steve

A.K. Boomer
11-30-2015, 10:07 AM
I too am looking around at led shot lights --- those costco's look like a good deal


if money was no object look what I stumbled across this morning - Big ass fans makes some shop lights, iv hung some of their fans in "wealthy peoples" houses and they don't mess around - very good quality stuff and yes they are proud of it to say the least,

but a full body aluminum led shop light complete with cooling fins, it's half the size of the costco's at only 2 ft in length yet puts out well over 4 times the lumens !!! and very cool looking - and oh yeah - 300 bucks :eek:

http://www.homedepot.com/p/Big-Ass-Fans-2-ft-Anodized-Aluminum-LED-Garage-Light-BAL-SHL1-13050104100900/205745341

A.K. Boomer
11-30-2015, 10:14 AM
You can get the matching ensemble fan kit too --- almost as much as I paid for my car lol

like I said - they are proud of their stuff :eek:

http://www.homedepot.com/p/Big-Ass-Fans-3600-144-in-Yellow-and-Silver-Aluminum-Shop-Ceiling-Fan-F-ES1-1201S34/206610543

ed_h
11-30-2015, 08:21 PM
There are a number of lighting calculators online to help with fixture spacing and layout. You need to start with a target for lumens per sq ft, but most of the calculators have tables for that for different kinds of spaces, like retail, restaurant, kitchen, workshop, etc. Using that as a guide, I installed 28 two-bulb 4 ft T8 fixtures in my 25 x 34 garage. Very pleasant to work out there now.

By the way, lumen output from bulbs varies some, even for the same wattage, depending on the phosphors used.

Ed

SteveF
12-01-2015, 09:03 AM
There are a number of lighting calculators online to help with fixture spacing and layout. You need to start with a target for lumens per sq ft, ...........................

And that is the problem with those lighting calculators, you need to know the target lumens per sq ft, and if you are using the calculator that means you really don't know what number you want. He can hang a single 60w LED bulb in the middle of the ceiling and get about 1 lumen per sq ft which is more than enough light to keep from walking into his machines and even enough to tell the difference between a standard and Phillips screw driver. Is that enough light for a workshop? Of course not. He can cover the ceiling with 4 tube fixtures and get about 1300 lumens per sq ft, which most of us would consider to be gross overkill.

Of the three of us that gave details, we have 25, 25 and 15 sq ft of floor per 1 T8 tube. For his shop that comes out to be 7 - 4 tube fixtures with the 25 number (about 105 lumens per sq ft in my shop). Toss in another to give 2 banks of 4 evenly spread across the ceiling and I'll bet after wiring it up he says "Yeah, that looks pretty good.".

Steve

RichR
12-01-2015, 10:14 AM
And that is the problem with those lighting calculators, you need to know the target lumens per sq ft, and if you are using the calculator that means you really don't know what number you want. ...

Which is precisely why I use the technique I described in reply #3. It allows you to visualize the results first hand because it takes into
account fixture height, fixture type, bulb color, color of surrounding environment, fixture spacing, etc. Or to put it another way:
A picture is worth a thousand words (or calculators).

SteveF
12-01-2015, 11:08 AM
I'd argue that by the time he temporarily hangs some fixtures and temporarily wires them up and steps back and evaluates the light and then moves them around and does some more evaluation, he could have divided his square footage by 25, bought those fixtures and be hanging them permanently up and when done says "Yeah, that looks pretty good." He's not the first person to have to cross this bridge.

Steve

ed_h
12-01-2015, 01:28 PM
If you are doing any kind of detailed work, you'd probably want at least 100 lumens per square foot, and 150 or even 200 would be better. A typical 4 foot T8 will put out maybe 2900 lumens.

Ed

lakeside53
12-01-2015, 01:59 PM
Lumens "where you are working" depends on distance from the source. Any decent lighting calc allow you to input the ceiling (or light distance) and work surface height.

RWO
12-01-2015, 02:04 PM
If you are doing any kind of detailed work, you'd probably want at least 100 lumens per square foot, and 150 or even 200 would be better. A typical 4 foot T8 will put out maybe 2900 lumens.

Ed
This is correct. My shop is 625 sq. ft. with white walls and ceiling. I have 25 Lithonia type LB fixtures surface mounted on the 8' ceiling. Each has 2- 4' T8 tubes. Considering the maintenance factor and coefficient of utilization, I figure I have about 100 lumens /sq. ft. at the work plane anywhere in the shop. I am 71 yrs. old and need more light than when I was younger. I still need small directional task lights on each machine. My fixtures are arranged in 5 rows of 5 with 3 rows on a single sw. and the remaining 2 rows on another sw. This allows a fairly uniform lumen level reduction if I don't need full level. I have had this set up for 9 yrs. and I wouldn't change a thing.

RWO

RussZHC
12-01-2015, 03:15 PM
Make no point on the line more than 4 feet from the wall or another light in any direction

Out of curiosity took a look at work, "work" being a sports facility, with the non-field of play being a mix of office, general open space and locker rooms.

The locker rooms have a mix of 4' fluorescents that are 2 lamp and 4 lamp, some with covers (the sort that fit into the space between joist, suspended ceiling) some bare (more like shop lights), all between 7.5 and 8 feet from the floor surface.
The range was all on the large side being between 6.5 feet and nearly 9 feet from the next light or wall. They are in rows as close to touching each other as possible if they are shop lights, most others are 8 foot apart, double the length of the suspended ceiling long measurement but also staggered in place to even greater distance.

Most importantly I think is that it became obvious when they put the lighting in originally, they did is as though the rooms would be just empty space which is it not and as cheap as possible.
There is space between the banks of lockers to fit the 2 foot dimension of the units BUT they could not because the joists run the opposite way, the result being the lighting is terrible. In many cases the best lit areas are the tops of the lockers. As per the "norm" someone just was not thinking or planning ahead when they installed the lockers.
I am lucky in that I have a bit of control over the area I spend the most time, there there is no more than 3' from fixture to next or to wall (all white) plus, as RWO said, additional spot light where needed IMO.