The Fluorescent Lighting System

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Section 7: Compact Fluorescent Lighting

Compact fluorescent lighting are a special category, consisting of an assembly that contains all the components needed to start and operate the attached lamp. These assemblies come with a screw-thread base that are meant to be installed in place of traditional incandescent lamps.

Compact fluorescent lamps are a fairly recent innovation, and are primarily targeted for use in residential situations, but it is also common to find them in commercial situations such as hotels and restaurants.

This section discusses this special category of fluorescent lighting.

Evolution of Compact Fluorescent Lighting

The Beginnings

Arguably, the earliest form of compact fluorescent lighting consisted of a screw-thread assembly containing a starter and ballast. From this central base, arms extended that held a round fluorescent lamp, also known by the trade name "Circline". This product was marketed as a power-saving replacement lamp for table lamps and sometimes included a special mounting bracket to adapt to the various supports used to hold the lamp shield of a table lamp.

These early lamps had numerous problems. The manufacturers failed to consider the areas where the lamps would be used, and tended to ship these lamps with cool white or similar phosphors that didn't blend in well with nearby incandescent lighting.

The next problem was that the combination of magnetic ballast and round fluorescent lamp was heavy, and made almost any table lamp top-heavy, resulting in accidents and lamp breakage.

The biggest problem of all was that these lamps only fit a tiny fraction of the possible lamp sockets in the average residence. An average three bedroom house has at least 28 incandescent lamp sockets, yet this solution could be used in no more than four of those locations on average. These lamps didn't really deserve to use the word "compact", and a better solution was needed.

The Miniature U-Tube

In the 1970s, several fluorescent lamp manufacturers introduced a the "U-Tube", a lamp that was shaped in a "U" shape. In most respects, it was identical to the T12 (1.5" diameter) lamps already available, but during manufacturing a glass tube of roughly four feet in length is formed into a "U" shape. Two of the finished lamps were then installed in a 2'x2' fluorescent fixture.

Previously, a fixture of that size that produced that amount of light would have required four 2' lamps, but this innovation allowed only two lamps to used, and a single ballast. Wiring was also simpler because all connections were on the same side of the fixture. With the growing popularity of 2'x2' drop-in ceilings, the use of these fixtures in commercial applications became quite popular and are still used today.

In the 1980s, someone exploited the U-tube design further, producing a miniature version in the T6 size (0.5" diameter) tubing. Now, the complete assembly of lamp, ballast and starter was narrow enough to be used in a few more locations where incandescent lamps were traditionally used and using fluorescent lighting were previously impractical.

However, this new miniature U-tube solution still had problems. It was still considerably longer than an incandescent lamp, so it could not be effectively concealed in many existing fixtures that were designed with an incandescent lamp in mind. Seeing recessed incandescent light fixtures with two inches of a six inch fluorescent lamp sticking out was a common sight in some hotels and restaurants, and to many this looked tacky.

The lamp and ballast were usually separate components so that the lamp could be replaced (some lamps also had the starter built into the lamp connector so that the starter would be replaced at the same time as the lamp), but this modular design also added more length and weight to the complete assembly. Plus, the manufacturers still continued to use cheaper cool-white phosphors, which hindered acceptance of these lamps further.

Although the magnetic ballast was still bulky and added even more length to the total lamp length, the big problem was that with the ballast located in the base of the lamp. Some fixtures don't have enough room to accommodate the ballast because the fixture clearance may be too narrow near the socket, an area where the typical incandescent lamp narrows as the glass meets the screw-base.

Despite these obstacles to use, the miniature U-tube compact fluorescent lamps made some inroads, but most found their way into new fixtures specifically designed for the longer length of the lamp, including outdoor porch lamps and recessed can lighting.

The Miniature Double-U-Tube

The basic problem with miniature fluorescent lamps is the issue of length versus light. The length of the fluorescent lamp dictates how much surface area is available for the phosphor coating that will create the light, and if you reduce the surface area, you will have less light. You can compensate to some extent by using more current arcing through the gas in the lamp, but that shortens the life of the lamp, which is also undesirable.

Some early pioneers in the compact fluorescent lamp market, notably Philips and Lights of America, hit upon a solution to the length problem, by taking the miniature U-tube design and bending the bulb not once but multiple times.

A typical lamp double-U tube lamp would start with the same length glass tube as in the current U-tube designs, say a twelve inch tube that was previously bent back towards the lamp base at the six-inch point. For the double-U design, you do things differently. At two inches or so from one end of the tube, the tube is bent at a right angle (now horizontal) to the west for an inch and then bend back down (now vertical) towards the lamp base, parallel to the first two inches of the tube. Two inches from that last bend, you make another right-angle one-inch horizontal bend (now parallel to the lamp base), but this bend was to the south, followed then with a bend up away from the base (vertical). Two inches further and you have another right angle bend with a one inch horizontal section, this time heading to the east, and finally another bend back towards the base (vertical). After executing all of those turns, you still have twelve inches of tube surface area, but the entire thing fits in a space less than 3"x3"x3", far closer to the size of an incandescent lamp than any previous design.

The double-U tube designs became the first of these lamps that could honestly use the word "compact". Some came with a plastic shroud that covered all of the twists and turns of the fluorescent tube, sometimes for waterproofing, sometimes to improve the color of the produced light, but these designs were far more successful than the single U tube designs.

A few manufacturers refused to adopt the double-U design, but instead put multiple smaller U tubes in their compact fluorescent lamps, wired in series. The result is pretty much the same, providing more phospher coating surface area in a smaller amount of space.

After a few years of selling the double-U and multiple-U tube designs, the electronic ballast started to appear in the compact fluorescent designs. This greatly reduced the weight of the lamps which were still overturning table lamps, and also provided faster lamp starting, now one of the few remaining shortcomings when compared to incandescent lighting.

Curiously, some lamp makers would use an electronic ballast but incorporate a traditional pre-heat starter bulb, which resulted in slow lamp starting. Gradually, rapid or instant start designs started taking over and the pre-heat compact fluorescent lamp became the rarity.

The "Twist" Tube

Although the double-U were constantly improved after its introduction, and some of these were eventually made of four separate tubes interconnected with small interconnecting glass pipes between the four main tubes that the electrical arc could pass through. This and other innovations improved the size and light output, but these lamps were much more difficult to make than a straight tube, and this made them expensive. This meant the lamp had to last several years before the cost of the lamp could be justified in electrical consumption cost savings.

In the mid-1990s, someone somewhere came across the solution to the manufacturing cost, and that was to build a tube that didn't have many or any sharp bends, but instead had gradual twists, a design that looks a lot like a soft-serve ice cream cone.

Originally appearing in the United States around 1997, the twist design revolutionized compact fluorescent design. Today, it is sometimes difficult to find compact fluorescent lamps that don't use the twist tube design.

Combined with electronic ballasts, warmer color phosphors and tighter and tighter tube twists, compact fluorescent lamps now exist that fit inside the physical dimensions of an incandescent lamp and produce the same amount of light, if not more. One design uses 13 watts to produce 800 lumens of light while a 60 watt incandescent of the same form factor may also produce 800 lumens of light. Such lamps can be obtained for as little as $4US retail, and at lower cost in quantities.

Compact Fluorescent Lighting Today

Today, compact fluorescent lamps come in many sizes and shapes ranging from 13 to 26 watts and producing from 500 to 1580 lumens of light, depending on lamp.

The manufacturers have finally paid attention to lamp color, and most lamps produce at least a semi-warm light, perhaps not as good as that produced by a warm-light straight-line fluorescent lamp, but not the cool-white colors of older compact fluorescent lamps. A few of the brightest compact fluorescent lamps produce a half-brightness "Post-It" yellow-colored or orange-colored light when they first start, but after two or three minutes they achieve their full brightness and the color becomes whiter, closer to that produced by halogen incandescent lamps.

Currently, the largest "plain" compact fluorescent lamps available consume 26 watts, but produce up to 1580 lumens, more light than a 100 watt incandescent lamp can produce. Such lamps have a 10,000 hour average life. A "sweet spot" lamp uses 23 watts, produces around 1400 lumens, and fits many fixtures.

The 1000 to 1580 lumen compact fluorescent lamps are a great innovation, because these high-lumen lamps can safely be installed in fixtures that could not previously use incandescent lamps larger than 60 or 75 watts. Incandescent fixtures with the 60 or 75 watt limits have those limits not just because of the current-carrying capacity of the wiring in the fixture but mainly because of the fixtures limited ability to handle the heat produced by larger incandescent lamps. The heat from the largest incandescent lamps can burn or melt materials in the fixture, and can cause the insulation on the wiring in the fixture to become brittle. Ceiling-mounted incandescent fixtures can also dry-out or burn ceiling plaster when incandescent lamps that are too large are used.

However, by using fluorescent lamps that use a fraction of the power and produce a fraction of the heat, you can still provide more usable light in a location than you could have ever obtained (safely) by using incandescent lamps.

With compact fluorescent lamps costing as little as $4US for 13 watt and $4.50 for 23 watt lamps, manufacturers are also trying to boost consumer acceptance by also providing two and three warranties on lamps, similar to the warranties manufacturers offer on halogen incandescent lamps.

Now that the physical size, weight and light color issues have been largely resolved in compact fluorescent lighting, all that remains to convince people to utilize these lamps is to convince them of the cost of ownership savings. These are discussed in detail in a later section.

Compact Fluorescent Lamps can't be used everywhere

There are some applications and locations where compact fluorescent lamps cannot be used. For example, the special-duty incandescent lamps used in ovens and refrigerators are designed to function in these extreme temperature ranges. Compact fluorescent lamps contain plastic components and electronics that would not withstand the heat of an oven, and fluorescent lamps do not work well at low temperatures. Further, if condensation forms, the electronics in compact fluorescent lamps could be damaged.

Unless specifically allowed, fluorescent fixtures and compact fluorescent lamps cannot be used for emergency lighting systems. Such systems may switch to battery power in an emergency. While incandescent lamps don't care if the power source is AC or DC, fluorescent fixtures with magnetic ballasts won't work at all if DC is used, and electronic ballasts may malfunction if DC power is used. Emergency power systems may also not generate the same voltage as normal commercial power, and this can cause ballasts to overheat or malfunction.

The vast majority of fluorescent fixtures and compact fluorescent lamps cannot be used with dimmers. Dimmable compact fluorescent lamps do exist and dimmable ballasts for traditional fixtures are also available, but these non-standard devices are typically special order components and may have to be specially ordered.

Compact Fluorescent lamps can't be used in certain life-safety applications. For example, any incandescent lamp that must be able to reach its full brightness immediately at all ambient temperatures should not be replaced with a fluorescent lamp of any type. This category includes airport runway lamps and traffic control signals. Gas-discharge lamps (Neon and Argon designs) are used in pedestrian Walk/Don'tWalk indicators, and are popular because of their very long life (typically 100,000 hours), but they have a higher initial cost than incandescent lamps.

Since the 1970s, the Uniform Traffic Control Devices standards specifically disallowed the use of fluorescent lamps to control traffic flow (red, yellow, green and direction indicators), although the original reason the idea was rejected was not because of the fluorescent lamp itself. The proposal requested that the signal heads be modified to allow each indicator to be a horizontal stripe 1'x4' in size (one stripe per color, with the shape selected to accommodate a four-foot fluorescent lamp, one per color or indication). When considered, it was felt that this change of shape would be confusing to drivers, so the proposal was rejected. (Note that newer traffic signals use solid state indicators made up of hundreds of light emitting diodes (LED), although their cost has slowed their deployment.)

Fluorescent lamps have been used for highway signage in many areas, but typically only in areas where winter temperatures do not fall below 10F. In areas with colder winters, fluorescent lighting is typically no longer used in highway signage because the lamps operate too dimly at these low temperatures, creating a safety hazard. The fluorescent lighting installed on "Green Signs" along interstate highway systems beginning in the early 1960s are now being replaced in states as far south as Texas with newer lighting systems that are capable of operating at colder temperatures without significant light reduction.

Finally, there is a class of incandescent lamp known as "Rough Service" that doesn't really have a compact fluorescent lamp equivalent. These lamps not only have heavier glass, but use more supports for the filaments, allowing the lamp to withstand much more vibration than a standard lamp. The starting filament is a weakness for compact fluorescent lamps, and usually isn't supported well enough to handle the shocks and other vibration that a rough service incandescent lamp can handle.

Things to Consider Before Switching to Compact Fluorescent Lamps

The two most common problems people encounter when attempting to switch to compact fluorescent lamps are the size of the lamp, and the warm-up period with the very low initial light levels that some lamps exhibit.

Although the size issue has been greatly improved in recent years, some compact fluorescent lamps will simply not go where an incandescent lamp that they supposedly will replace went. Obviously, you can't use compact fluorescent lamps in ovens or refrigerators, but many globe, ball or recessed fixtures simply exceed the length or width clearance needed. In some cases, the socket itself is at fault. I have a garage door opener and the lamp sockets on it are made in such a way that the wider base of the compact fluorescent lamp will simply never screw in, even though there are no other size restrictions on the lamp itself.

The warm-up problem is something that has surfaced in some of the more recent compact fluorescent lamp designs. For a variety of reasons, these lamps initially illuminate at less than their full brightness, and in some cases less than 20% of their full brightness. They then take up to five minutes to reach their full brightness levels EACH TIME they are turned on. For commercial environments where lamps are turned on and left on for the entire business day, this may not be an issue. However, for home use, this "slow warm-up" is a real negative, and can prevent the use of Compact Fluorescent lamps in certain areas. Even businesses that use power saving systems which turn lamps off in unoccupied areas can have issues with this warm-up problem.

For example, I have a light fixture over a bathroom sink that holds four of those bare 40 watt incandescent "globe" or "sphere" frosted lamps. These fixtures are fairly common. There is a compact fluorescent replacement for these lamps. The compact fluorescent lamp is almost the same size, and when fully illuminated, it produces a brighter light than the 40 watt incandescent lamps did, all for 13 watts or so per compact fluorescent lamp. However, the brand I happened to buy ("Techna Bright", purchased from CostCo) takes a full five minutes to achieve that full bightness each time it is turned on. Each time you turn them on, they initially produce about 20% of the rated light levels, leaving the bathroom so dark as to be a safety hazard.

Few people are willing to wait for the lights in a bathroom or restroom to "warm up" before entering it, so I ended up putting two of the incandescent lamps back, so that there would be a usable light level in the room immediately. Subsequently, the power savings in my situation is about half what it could have been, if the compact fluorescent lamps came on at a brightness far closer to their rated value. (A search for a vendor who makes a similar lamp without this undesirable artifact has so far turned up nothing.)

Closets would also be a problem for lamps that need to warm up. Who is going to go in a closet, turn on the light, and then wait five minutes before it is bright enough in there to find what you originally wanted to get?

Of course, few manufacturers of Compact Fluorescent lamps mention the fact that a given model of lamp requires a warm-up period before it produces 80%* or more of the stated lumens, even at normal room temperatures. I have seen this same behavior in Compact Fluorescent "Flood" lamps sold under the Westinghouse (now only a trade name used by Philips in North America) and other brand names. At least Westinghouse/Philips mentioned on the packaging that not all of the tubes that make up the lamp would illuminate immediately, but they didn't explain that this meant that the lamp comes on at about one-third of its eventual light output.

The lesson here is to not purchase a large quantity of Compact Fluorescent lamps until you have determined a given brands behavior and decided if you are willing to accept any quirks that may accompany that particular type of lamp. If it is possible to test one of the lamps in a store prior to purchase, consider doing that. Make sure the lamp being tested has been off for at least an hour or else you will see better warm-up results than you might normally get.

Hopefully, manufacturers will hear this feedback and return to making compact fluorescent lamps that turn on immediately and are at or near full brightness in seconds, not minutes. Strangely, in lamps made in 2000 and earlier, this warm-up problem was not an issue. Only in some lamp types that have appeared since that time has this warm-up problem become so significant.

* The value of 80% mentioned above was selected arbitrarily. Virtually all fluorescent lamps produce less than 100% of the rated light each time they are turned on, but for most brands of lamp, the power-up brightness is typically within 20% or so of the rated brightness and full brightness is achieved quickly. In my opinion, initially producing 80% or more of the rated light would not be a problem to most consumers. It's the compact fluorescent lamps that initially produce less than half or even less than a third the rated light when first illuminated that are the main problem.

Shop around when purchasing Compact Fluorescent Lamps

Pricing on Compact Fluorescent lamps is highly erratic, at least in the stores I have visited. Warehouse stores like Costco or Sams consistently sell compact fluorescent lamps in quantities of four to ten lamps per package, and you will pay anywhere from $10 US to $18 US for that package of lamps. In these small quantities, the individual price for each 800 lumen (13 watt) lamp is commonly at or below $2 US and a 1400 lumen (23 watt) lamp can be purchased for around $2.50 US. This is about 1/5th of what lamps with similar lamp output cost just four years ago.

However, if you to go Home Depot or Lowes, expect to pay anywhere from $4 to $7 for that same compact fluorescent lamp. The prices for these lamps at both of these chains have been quite slow to go down.

Worse, if you go to WalMart, Walgreens, CVS, KMart, Target or similar retailers, expect to pay between $7 US and $10 US for one compact fluorescent lamp and it sometimes it is an older and physically larger design than the current models. The most off-base price I saw in Summer 2004 was a physically enormous 23 watt model sold at Walmart for $19 US, a completely obsolete price and obsolete physical design.

A lot of this price imbalance is caused by the use of name brands. At Sams or Costco, the plastic package with four to ten lamps in it may claim to be from a company that you haven't heard of or rarely hear of. Meanwhile, if it is at Home Depot or Lowes, they are sold under the one or two brand names of lamps that the store carries. Home Depot seems to be stuck on Philips for the bulk of their lamps, and Feit for the rest, while Lowes sells Sylvania for most of their lamps and uses Lights Of America and sometimes a few Westinghouse/Philips lamps for the rest of the sizes they wish to carry.

This split of brands between store chains is intentional and is done to prevent the consumer from being able to utilize the price match guarantee both chains offer. You'll never find a Philips lamp you bought at Home Depot for less at Lowes because Lowes avoids selling that brand, and Home Depot will never be cheaper than Lowes on Sylvania lamps because Home Depot avoids selling Sylvania products. Effectively the two companies agree to not compete against each other in this way on most of their offerings.

As you get into the Walmarts and other consumer "household" retailers, expect to see even more expensive brand names like General Electric on the compact fluorescent lamps that are offered.

What's interesting about all of this is that most of the compact fluorescent lamps made today and sold in the US are produced in the same factories in China, with only the packaging and an external label on the lamp reflecting the different brand names. So the 13 Watt "Warm White" lamp sold at Costco in a package of eight is frequently the exact same lamp sold under three other brand names at other stores for as much as six times the price.

Of course, Home Depot or Lowes will likely offer you a lot more choices, in that they probably have Compact Fluorescent lamps available in "Daylight" and other color shades as well as more sizes, but if you just need the plain warm white 800 (13W) or 1400 (23W) lumen compact fluorescent lamp sizes to replace incandescent 40, 60, 75 or 100 watt incandescent lamps, then you can save yourself a lot of money by doing some price checks first.

Despite all this, even if you end up paying $10 US instead of $2 US for the same compact fluorescent lamp, the fluorescent lamp will still be more economical than the pile of incandescent lamps it will replace and outlast over its operating life, when you include the electricity costs as well. Still, paying $2 instead of $10 makes that initial investment a lot easier to accept.

Although it costs between $35 US and $45 US to initially get in the door of a Costco or Sam Club (unless you know someone who already has a membership), if you are planning on buying at least 8 or more compact fluorescent lamps of the warm white color (most common type made), today it is probably cheaper to pay for the club membership and then get these far lower prices on the lamps, even if you don't buy anything else there. If you are thinking of buying hundreds of these lamps all at once for a place of business, church or other large facility, you need to find a wholesale distributor who can get you an even better price.

Related Topics

Section 8: Fluorescent Lighting Energy Savings and Product Comparisons (HTML) [NEXT]

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[Copyright 2002,2004,2005 Frank Durda IV, All Rights Reserved.
Mirroring of any material on this site in any form is expressly prohibited.
The official web site for this material is:
Contact this address for use clearances: clearance at
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