In our office, we currently have this type of fixture used for our main source of light:



It's a pretty basic fixture--up to 300 watt fixture with the frosted glass enclosure and the cage that you see in the photo above. We currently use 200 watt incandescent bulbs because we need more light than what a 60 or 100 watt bulb offers. All the lights are on dimmers as well. We've been purchasing the bulbs from a local electrician's supply store, and they're 5000 hour 200watt commercial grade bulbs. They are not cheap bulbs, and based on the recommendation of the owners of the supply store (knowledgeable folks), we trust that they are good bulbs.

The issue:

Because of the high wattage of the bulb, and the nature of the fixture/enclosure, the bulbs are blowing out quite quickly (probably after a couple hundred hours each). I just replaced another one this morning:



We realize that it's probably due to heat building up in the fixture/enclosure, and because it simply doesn't have a way to escape, it's shortening considerably the life of the bulbs. This is not a good thing, both because it's a pain to have to get out a ladder to change a bulb every couple of weeks, and also because the bulbs should last about 2 years under optimal conditions (based on the 5000 hour rating assuming 8 hours usage a day). We've been in this office using these lights for just over a year, and we've already needed to change most of the lights at least once--some twice.

My question:

What can we do to fix this situation? We don't really want to replace all the fixtures, because we like how they look and it would be a pain and expensive to get them all replaced. We've switched to CFL bulbs at home, and have noticed a marked decrease in our monthly electric bill, and wondered if there'd be anything out there that could meet our needs and perform in a similar fashion.

Is there any type of CFL bulb that could:
1. Have output equivalent to 200watts
2. Be dimmable
3. Have a pleasing color

?????

I know initial costs for regular consumer-grade 60/100 watt CFL equivalents are a little more expensive than incandescent bulbs, and I know something as highly-specialized as what we need in a CFL might be considerably more expensive, but I think the long-term savings would more than make up for any initial costs.

Or is there another option that I'm simply not aware of? Thanks!

Couldn't you just take off the glass cover?

Upside-down bulbs in enclosed fixtures are doomed to fail early. Incandescent bulbs are hot to begin with of course, but the heat that builds up in an enclosure like that is extreme.

You could drill a series of small holes around the bases of the glass enclosures. You run the risk of breaking them however.

I don't think there are any dimmable CFL bulbs out there. Do you really need that feature? I've discovered that with the bulbs I've replaced in my home with CFLs, I haven't felt the need to dim.

There are nicely-colored CFL bulbs.

You might also have difficulty fitting a 200-watt equivalent inside the enclosure, although doing so would definitely help the heat problem. (I'm not sure they work so well upside down however--I think that makes them burn out early.)



Edited 1 time(s). Last edit at 02/28/2007 10:12AM by tenders.

Halogens.

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BT


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Dimmable CFs are around, and come in a bunch of color temps.

Maximum wattage available I do not know.

CFs can suffer from high temps in enclosures like yours as well.

I wasn't aware of the fact that they are upside-down might contribute to them burning out more quickly, but that would make sense, I suppose.

In response to some of the other suggestions:

>>Removing the glass globe
My bosses like the look of the lights with the globe on, and probably wouldn't be too keen on removing the globes

>>Drilling holes in the globe
A possibility, I suppose, but I'm a little hesitant to use a drill in combination with glass! Seems like there'd be a good possibility of breakage, imo

>>Do we really need dimmable lights?
We probably could get away with not using dimmable lights, but co-workers really do like being able to dim the lights during presentations, etc.

>>Halogens?
Wouldn't we still have heat issues with these?

Keep the suggestions coming, please! Thanks!

Quote
papercup
Dimmable CFs are around, and come in a bunch of color temps.

Maximum wattage available I do not know.

CFs can suffer from high temps in enclosures like yours as well.

But wouldn't the temps be significantly lower than incandescents?

i second everything papercup said.

i think you'll just have to try things and see what works.

I'd try a couple of CFL bulbs. If those die early then remove the glass or drill holes.

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Dimmable CFL exist and they suck.

I've spent a lot of time and money trying to convert ANY of the lights in my house to CFL and can't.

Almost every light is controlled by a dimmer and was placed with the idea that it would be used as task lighting (eg - instead of lighting a whole room with 200W, use task lighting and use only 80W where necessary).

All dimmable CFLs that I have tried have a short delay when turned on (under 1 sec), take at least 30 seconds to come up to full brightness, and hum when dimmed.

Mind you, all of this is purely to save me money and has nothing to do with the environment because all my power is already sourced from green resources.

See if any of these will work for you:
[www.ccrane.com]

You'll never need to replace them more than likely. No heat. MUCH more efficient than either CFL or Incandescent lights. There are many other sources. This was just the first link that I found with Google.

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I suspect the dimmers are adding to the early failure of the bulbs...

I second trying a few CF's to see if you like 'em.

I would also add that those fixtures are LOUSY office lights..
Those are SHOP LIGHTS, not office lights.

I don't think CF"s can be conventionally dimmed.

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Paul F.
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LED lightbulbs would be ideal for this application, although you are probably a few years early, unless you want to be an innovator. ($$$)


See here: [www.superbrightleds.com]

[www.1000bulbs.com]

This is a great site. They have no dimmable bulbs over about a 90 Watt equivalent but they may exist.

As already mentioned, enclosed fixtures can shorten the life of fluorescent bulbs because of heat buildup. If you want to keep the dimmable feature, I would recommend spending a couple of hours trying to find a 200 Watt halogen. They should last longer.

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You need to find long life bulbs that are filled with a halogen gas- probably Krypton. Not the quartz halogen bulbs that people think of when you say halogen- those burn hot and need good ventilation. Based on how smoky the glass looks, the bulbs you are using don't look to be gas filled. Ask your light guy about something like this: [www.whatwatt.com]

EDIT: The type of bulb I am talking about it also referred to as a traffic light bulb and is made to withstand abuse.

BT



Edited 1 time(s). Last edit at 02/28/2007 10:42AM by Baby Tats.

If you can lose the dimmable requirement then there are some high wattage CFLs.

Here's a good site to get some idea of what's available.

[www.1000bulbs.com]

As other have said, they do make dimmables, but they are in very limited sizes/shapes/wattage.

One thing that I saw some mention of last year when searching for dimmable CFLs was CFL friendly Dimmer Switches, which presumably allow use of standard CFL bulbs, but I never ran across any of those switches. Anyone have any knowledge or experience with something like that?

You may have a voltage issue leading to short bulb life. When I first moved into my house, bulbs were lasting only a few months. I happened to check the voltage and it was 137. Called the electric company and they wound up adjusting the pole mounted transformer. Bulb life went up significantly after that.

Upside-down bulbs in enclosed fixtures are doomed to fail early.

Exactly.

Standard halogens are out, and I'm not so sure the bulb BT mentions will live long in an inverted, enclosed fixture.

In fact, even though LEDs are much cooler, being inverted may cause failure in the base, if any electronics are involved. That's what kills inverted CFLs.

Some holes in the glass (use a carbide bit) might extend the life a little, but I would bet not much. If the fixture can be removed, it might be possible to drill into the base. Even then, I don't think there would be a huge difference.

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Oops, I misspoke. You need to find bulbs that are filled with a noble gas (not halogen gas). It is usually krypton that is used. Also look for bulbs that support the filament well. Inverting the bulb is ok as long as the filament is well supported since it sags (melts) when it gets hot.

BT

FYI, most CFLs are not rated for any enclosed fixture due to heat buildup. Yes, they still run a lot cooler than incandescent but that's not the point - it takes much less heat to damage the electronics inside the CFL bulb's base so that's why they aren't rated for enclosed fixtures (and also upside down installations).

Of course that hasn't prevented me from installing about a half dozen in enclosed and upside down fixtures but I'm willing to make the compromise.

don't halogen and similar bulbs use a lot more electricity?

thats been my impression.

Those are safety fixtures.
In some locations they are code required.
For an office they don't make sense unless something exists there where a bulb could get hit. Or high humidity environment. Are your ceilings extremely low ?

Absolutely do not put a halogen in there.

They do require heat capable bulbs which it sounds like you have.
Especially over 60 watts.

Has the dimmer been replaced lately ?
Some can make a "hum" (just like with flourescents) which vibrates the filament which shortens the life.
I'd lose the dimmer for an office, but mostly because I don't quite understand why, if, you need a 200 watt bulb, you need a dimmer.

Vibrations from above the fixture could be a problem, too.

You do not want to be drilling holes in the glass nor in the base .

Right side up / upside down could be argued all day.
It can be fun to get two 'lighting experts' arguing about it and then sit back and watch the action.


I'd change brands of bulb just for a try, you may be working with a bad batch. It happens.

BTW, I have those fixtures in my cellar (very low ceiling) mounted sideways (head knockers) with CFL in them, no dimmers. Glass cover, aluminum safety grid (not ABS)

in our office, they were used for aesthetic reasons, and they fit very well with the "look" of our office (very modern with industrial-type touches). Nothing to do with code, or other environmental factors. The ceilings are probably 10'.

Dimmers have not been replaced--they were installed new just over a year ago by professional electricians.

The frosted/smoky glass globes block enough light that a 100watt bulb simply doesn't provide enough light for us. We need/want the dimmer because it's nice to be able to dim the lights for presentations where a projector/big-screen is being used, or in our editing suite when showing a client a finished video edit on the production monitor. There are certain parts of our office where we could probably get by without the dimmers (i.e. the storage room and a couple of other locations).

We have tried several different brands of bulbs as well as this same type from different lots, so I don't *think* it's an issue with the bulb--be it a manufacturing defect or whatever.

I think I will suggest switching at least a couple of the bulbs to high output CFL to see how they do. Then, we can make a gradual rollout office-wide if we decide they work for us.

I agree that heat buildup may be a contributing factor but I would bet that the problem is most likely from dirty power. Power surges/spikes/dropouts are the biggest killers of lights (and other electronics). Does your office have a power conditioner?

[www.phasetechnologies.com]

As a side note, the glass bowls for the lights could safely be drilled with ventilation holes using a diamond tipped drill bit made for ceramic/glass. A job best left to a professional!

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I have drilled wine bottles with those carbide drills in a small drill press here at work. No big deal slow to medium speed, medium pressure. Bacvk it out every few seconds to let everything cool.

I despise clear glass bulbs - they cast a harsh, shadowy light. You can increase the perception of light simply by switching to a super soft white reader bulb. I would hybridize with a mix of lower watt incandescents and CFLs. Put a 75 watt in the overhead fixture and fill an inexpensive torchiere with a 100 watt equivalent CFL to cast some uplight into the space.

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I've seen plastic globes at Home Depot or Lowe's. In fact I bought one and drilled some holes in the upper side for ventilation. But they may or may not be "code" in certain installations.

LyleH

unless it is an explosion proof fixture for use in areas that may have flamable vapors, or a waterproof fixture for emergency lighting, drilling some holes isn't a bad idea.

My only concern with drilling holes in the base would be the base can act as a heat/fire stop.

We all know when a three lamp ceiling fixture is marked 60watt max per socket, 150 watt total fixture, that means if you put a 150 watt bulb in just one of the sockets, the ceiling will catch on fire. Right ?

>>if you put a 150 watt bulb in just one of the sockets, the ceiling will catch on fire. Right ?

Did you build your house out of straw?

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The dimmer lowers the voltage. The amps increase as volts decrease if resistance stays the same. It is the law.This shortens the bulbs life. The bulb you showed was rated for 130 volts and that is the secret for longer life as the power companies do not regulate the power levels like they used to. Run the bulbs wide open and if that is to bright, use a smaller bulb.

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Staunton, Virginia

for every 10% decreas in voltage to an A/C bulb, the life roughly doubles. For every 10% increase, the life roughly drops 50%. So if you have @135 volts (as someone here did in a recent thread) their bulbs were only lasting about 1/3 their expected life. And overvoltage in a halogen bulb is very dangerous as they will get too hot and burst. I have a few I keep at work to show some people when they don't believe me. Molten eruption of quartz glass that immediately cooled, and left either a bubble in the glass, or what looks like the ejecta from a glass volcano.

Thats why when the charging system in a car shorts and the alternator's regulator goes full field and puts out 17 or 18 volts, the headlights go almost immediately.


Could you go frosted long life bulbs, and eliminate the glass cover, leaving the cage? Or is the globe required by building code?



Edited 1 time(s). Last edit at 03/01/2007 05:32PM by Racer X.

My approach would be to lose the dimmers and globes and use CFLs. CFLs will be softer anyway so globes won't be necessary but spiral CFLs won't look as pretty while exposed in the fixtures. You might be able to find globe-encased or other "pretty" CFLs and get the same amount of light from them minus the globes you currently have.

But it seems to me that dimmers and energy-efficient high output light don't go together.

Lose the dimmers and just turn off the lights if you need to do a presentation. You can either have accent lights provide enough light to keep from stubbing your toe during a presentation or rewire so that you can turn off some of the lights.

However, if this is really the way your bosses feel about it and are not flexible:

Quote
clay
>>Removing the glass globe
My bosses like the look of the lights with the globe on, and probably wouldn't be too keen on removing the globes

Then they will just have to continue to foot the bill for replacement bulbs and higher electricity costs.

BTW, it wouldn't hurt to have your electricity checked.

Quote
Bernie
The amps increase as volts decrease if resistance stays the same. It is the law.

V=I*R

The voltage and current are directly proportional for a fixed resistance. Increase the voltage, increase the current. But your point about using bulbs rated for a higher voltage is correct. Bulb manufacturers design bulbs to run the filament close to the melting point of tungsten to give the greatest efficiency. Using a bulb rated for higher voltage will cause the bulb to burn cooler and last longer.

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BT


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