I highly recommend the 4' T8 fixtures. More light, less power, easier to find the bulbs.

Hi housavvy,

Thanks. I am thinking that way myself. I hate that I spent anything on those old 8' fixtures, but I would rather dump them now rather than taking all the time to put them in and be disapointed with the light output.

I was alarmed at how much dimmer the T12 8' 60W bulbs were as compared to the T12 4' 40W. Night and day.

Your 8' lamps may be old. Light output decreases with age, though usually not enough to be alarming.

That said, T8 lamps with electronic ballasts are significantly superior to T12 lamps with magnetic ballasts. It's easier to find T8 lamps with high CRI, and the system is more efficient in terms of light output per watt.

Now that I hear from you guys I feel stupid for buying these T12 fixtures. I am going to cut my losses and go with new T8s.

Thanks for your advice!

Actually, there's nothing wrong with saving usable fixtures from the landfill. Since you have these already, why not use them? They may not be as efficent or produce light as nice as newer ones, but they're certainly more efficient than incandescents. If they meet your current needs, I'd say go ahead and use them.

Normally I would agree with you, but when i say dim, I mean probably half the light or less as compared the the 4 ' t12 40W. And that is with new or old bulbs. The light output just is not enough. I am betting these fixtures are many many years old. I may be able to fix them with new ballasts, but in the end I think I would be better off doing it right.

I am taking the old fixtures to the habitat for humanity store. Maybe someone can use them.

You may be comparing standard F96T12 lamps with high output F48T12s. In fact, 60 watts for a F96 lamp is unusually low; most are in the 95-110 watt range.

Then recall that a F96 lamp has twice the surface area of an F48 lamp. It wouldn't be too surprising if 50% more light spread over twice the surface area seemed dimmer.

That said, I probably would have done the same thing. I like T8 lamps much better than T12. In theory it shouldn't make that much difference, but the most readily available T12 lamps are definitely old-school, with the better phosphors more readily available in the newer T8 lamps.

Hello Davidr,

Thank you for your last post. It was an aspect of fluorescent lighting I had wondered about, yet could not find information on.

Help me clarify some of your statements. So the key to fluorescent brightness is the relationship of the wattage against the surface area of the bulb. Then obviously a 4' T12 compared to an 8' T12 of same wattage would appear 1/2 as bright. Makes sense.

Now since the T8 is smaller diameter and thus a smaller surface area does that help add to the brightness?

Now for the total dummy question- I am so used to cfls claiming 13 watts = a 60W incandescent. I was sort of surprised when looking at for instance the T8 34w tubes. Two 34w = 68 watts for the one fixture. Compared to the CFLs it just seemed a lot higher energy use, but then again the cfls are dim by comparison.

Should I plan for the usage of each 4' T8 fixture to be 68W?

Be careful - brightness isn't the same thing as light output.

For example, a typical high output LED is EXTREMELY bright, so bright you can't look at it. But if you try to light up the room with it, the results will be kind of mediocre.

A 20 watt compact fluorescent screw-in retrofit will appear dimmer, easier to stare at, but it will do a much better job of lighting up the room.

An F32T8 (32 watt, 4', T8 linear fluorescent lamp) will be easier still to look at, but it will light up the room still better.

Brightness is great for traffic lights and auto taillights, so you can see them through fog. But when you want to light up a room, it's not brightness you care about, it's luminous flux. That's what lights up your work area. That's measured in lumens. And a 32 watt linear fluorescent has a LOT more lumens of output than the typical retrofit LED or CF. Of course, it's bigger, too.

For example, a 20 watt CF will produce 1000-1400 lumens (depending on brand and design). A "32 watt" linear T8 fluorescent will produce 2800-3100 lumens (depending on similar factors).

However, I put quotation marks around "32 watt" because the T8 isn't actually using 32 watts.

A little clarification on fluorescent lamp power usage and output might help here. This is probably WAY more than you really want to know, but here goes.

A standard F32T8 lamp is rated 32 watts. However, there's an important difference between incandescent lamps and fluorescent lamps.

The wattage used by an incandescent (at a given line voltage) is purely a matter of its design. At 120 volts, a 40 watt bulb will use almost exactly 40 watts.

This isn't so with fluorescents. Both the lamp design and the ballast used affect how much power the lamp uses (and consequently how much light it produces).

The interesting part of this is what we call the ballast factor. BF typically varies from .70 to 1.15. A F32T8 (32 watt, 4' T8 tubular or linear lamp) lamp operated on a .70BF ballast will use about 22.5 watts. The same lamp operated on a 1.15BF ballast will use almost 37 watts. That's quite a difference.

You'd think that a "standard" or "normal" ballast would have a 1.0BF, but nooooo. Standard ballasts are usually around .88BF, so your usual "32 watt" T8 actually will use about 28 watts.

Fluorescent lamps are rated for the number of lumens they'll produce with a standard ballast. A typical cheap F32T8 will produce 2800-2900 lumens, while a more expensive high output F32T8 will produce 3000-3100 lumens. (The better lamp will usually last longer, too.)

If you do the math you'll see that this is an efficiency (efficacy) of 100 to 110 lumens per watt. This is quite a bit better than the screw-in retrofit CFs I mentioned above, which run 50-70 lumens per watt. (And, incidentally, also quite a bit better than any currently available LED fixture or retrofit that I'm aware of.)

So to come to the point - unless you special-order fluorescent fixtures with high or low ballast factor, normal ballast factor is most likely what you'll get. Thus, each of your 2-lamp fixtures will probably use about 56 watts (not 68 watts).

Also, they will produce more lumens per watt of electricity than either screw-in compact fluorescents or T12 linear fluorescents.

You also mentioned CFs and their claims of incandescent equivalence. This is kind of a sore point, because early CFs (15 years ago or so) were notorious for overstating this. Fortunately they're more conservative today.

A good rule of thumb is that a retrofit CF will produce about as much light as an incandescent with 4 times its rated wattage. For example, you mention a CF claiming "13 watts = a 60W incandescent," which isn't too far off. A standard 1000 hour 60 watt incandescent produces about 850 lumens (a shorter-lived one will produce more lumens, a long-life one less). When I look around at 13 watt CFs, I see lumen outputs from 760 to 900 lumens.

Whew, this was long. Sorry! Did I help at all?

Davidr, real good explantation!

Do you have any good websites for fluorescent lighting and which ones to choose for can CFLs and normal CFL bulbs? Thanks.

I usually buy linear fluorescent lamps, ballasts, and fixtures from a large local electrical supplier. They're actually a bit cheaper than the big-box stores here on most items. When it comes to fluorescent lamps, they have a huge selection of various brands, qualities, color temperatures, and CRI.

I haven't bought many CFs in recent years. Back in the early to mid 2000s, I settled on a few kinds that I liked, and bought quantities of them when they were on sale. So I probably have something close to a lifetime supply of CFs sitting on shelves in my cellar. :)

This means that I haven't traded with any of the websites offering CFs. About all I can say is that when I want information on CFs - what's new - I usually go to 1000bulbs.com and/or energyfederation.org. However, I have no idea how good those vendors are when it comes to actually SELLING CFs and other stuff. Sorry.

If you browse through some of the older posts here, you may find some better recommendations for vendors than I can give you.

Hope this helps at least a little.

Use 4-foot fluorescent fixtures with reflective backing and electronic ballasts for entire basement. This is more efficient.

To davidr if you are still hanging around:

Hello,

I have an artists studio residency that has a fixture that takes two 96" single pin bulbs. I would like to get new bulbs that will give me the closest color lighting to natural daylight and not distort the color of the paint. Does such a thing exist?

One wall is all windows and faces southeast so during the day I am ok but I am a night owl.

I would really appreciate advice.

Thank you,
Victoria