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Fluorescent Signs


For reasons made obvious from the information shown below, in May 2008, Gigantic Signs has made a World First Claim as a major signage producer of internally  illuminated signs. “We will never again use fluorescent lighting as the primary light source in Illuminated Signs”



What are the drawbacks to the new fluorescent lamps I've heard so much about?


One need look no further than good ole Wikipedia for your answers, you know the benefits of LEDs and that they will last 5-7 times longer than Fluorescent but here is the rest of the story:


A fluorescent lamp is a gas-discharge lamp that uses electricity to excite mercury vapor in argon or neon gas, resulting in a plasma that produces short-wave ultraviolet light. This light then causes a phosphor to fluoresce, producing visible light.
Unlike incandescent lamps, fluorescent lamps always require a ballast to regulate the flow of power through the lamp. In common tube fixtures (typically 4 ft (120 cm) or 8 ft (240 cm) in length), the ballast is enclosed in the fixture. Compact fluorescent light bulbs may have conventional ballast located in the fixture or they may have ballasts integrated in the bulbs, allowing them to be used in lamp holders normally used for incandescent lamps.


Mercury toxicity of fluorescent lamps


Because fluorescent lamps contain mercury, a toxic heavy metal, governmental regulations in many areas require special disposal of fluorescent lamps separate from general and household wastes. Mercury poses the greatest hazard to pregnant women, infants, and children.


Landfills often refuse fluorescent lamps due to their high mercury content. Households and commercial waste sources are often treated differently.

The amount of mercury in a standard lamp can vary dramatically, from 3 to 46 mg. [1] Newer lamps contain less mercury and the 3-4 mg versions are sold as low-mercury types. (A typical 2006-era 4 ft (120 cm) T-12 fluorescent lamp (i.e., F32T12) contains about 12 milligrams of mercury [2].)


In early 2007, the National Electrical Manufacturers Association in the US announced that "Under the voluntary commitment, effective April 15, 2007, participating manufacturers will cap the total mercury content in CFLs under 25 watts at 5 milligrams (mg) per unit. CFLs that use 25 to 40 watts of electricity will have total mercury content capped at 6 mg per unit."NEMA Voluntary Commitment on Mercury in CFLs


Cleanup of broken fluorescent lamps

A broken fluorescent tube is more hazardous than a broken conventional incandescent bulb due to the mercury content. Because of this, the safe cleanup of broken fluorescent bulbs differs from cleanup of conventional broken glass or incandescent bulbs. 99% of the mercury is typically contained in the phosphor, especially on lamps that are near their end of life [3]. Therefore, a typical safe cleanup usually involves first opening a window and then leaving the room (restricting access) for at least 15 minutes, wearing gloves carefully dispose of any broken glass, as well as any loose white powder (fluorescent glass coating). You can use sticky tape to pick up small pieces... double bag any waste. Dispose of waste in accordance with local hazardous waste laws. Finally a wet paper towel should be used instead of a vacuum cleaner for cleanup of glass and powder, to reduce the vaporization of the mercury into the air.

The first time you vacuum the area where the bulb was broken, remove the vacuum bag once done cleaning the area (or empty and wipe the canister) and put the bag and/or vacuum debris, as well as the cleaning materials, in two sealed plastic bags in the outdoor trash or protected outdoor location for normal disposal [6]

It would be safer to use a vacuum cleaner with a HEPA filter, because older-type vacuum cleaners don't trap really-fine dust. That dust is exhausted into the room, which spreads it.


Fluorescent lamps manufactured many decades ago had phosphors that contained beryllium, which is toxic. One is not likely to encounter lamps this old.


Ultraviolet light from fluorescent lamps


Fluorescent lamps can cause problems among individuals with pathological sensitivity to ultraviolet light. They can induce disease activity in photosensitive individuals with Systemic lupus erythematosus; standard acrylic diffusers absorb UV-B radiation and appear to protect against this.[4] In rare cases individuals with solar urticaria (allergy to sunlight) can get a rash from fluorescent lighting.[5]

Ballasts and fluorescent lamps

Fluorescent lamps require a ballast to stabilize the lamp and to provide the initial striking voltage required to start the arc discharge. This increases the cost of fluorescent luminaires, though often one ballast is shared between two or more lamps. Electromagnetic ballasts with a minor fault can produce an audible humming or buzzing noise.

Conventional lamp ballasts do not operate on direct current. If a direct current supply with a high enough voltage to strike the arc is available, a resistor can be used to ballast the lamp but this leads to low efficiency because of the power lost in the resistor. Also, the mercury tends to migrate to one end of the tube leading to only one end of the lamp producing most of the light. Because of this effect, the lamps (or the polarity of the current) must be reversed at regular intervals.

Power factor of fluorescent lamp ballasts

Fluorescent lamp ballasts have a power factor of less than unity. For large installations, this makes the provision of electrical power more expensive as special measures need to be taken to bring the power factor closer to unity.


Power harmonics of fluorescent lamps

Fluorescent lamps are a non-linear load and generate harmonics on the 50 Hz or 60 Hz sinusoidal waveform of the electrical power supply. This can generate radio frequency noise in some cases. Suppression of harmonic generation is standard practice, but imperfect. Very good suppression is possible, but adds to the cost of the fluorescent fixtures.


Optimum operating temperature of fluorescent lamps

Fluorescent lamps operate best around room temperature (say, 20 C or 68 F). At much lower or higher temperatures, efficiency decreases and at low temperatures (below freezing) standard lamps may not start. Special lamps may be needed for reliable service outdoors in cold weather. A "cold start" electrical circuit was also developed in the mid-1970s.


Non-compact light source

Because the arc is quite long relative to higher-pressure discharge lamps, the amount of light emitted per unit of surface of the lamps is low, so tube lamps were large compared with incandescent sources. However, in many cases low luminous intensity of the emitting surface was useful because it reduced glare. The bulk created by this lamp affected the design of fixtures since light must be directed from long tubes instead of a compact source.


Recently, a new type of fluorescent lamp, the CFL, has been introduced to address this issue and allow regular incandescent sockets to be fitted with this type of lamp, thereby negating the need to mount it on special fixtures. However, some CFLs intended to replace incandescents will not fit some desk lamps, because the harp (heavy wire shade support bracket) is shaped for the narrow neck of an incandescent lamp. CFLs tend to have a wide housing for their electronic ballast close to the lamp's base, too wide to fit.


Flicker problems of fluorescent lamps


Fluorescent fittings using a magnetic mains frequency ballast do not give out a steady light; instead, they flicker (fluctuate in intensity) at twice the supply frequency. While this is not easily discernible by the human eye, it can cause a strobe effect posing a safety hazard in a workshop for example, where something spinning at just the right speed may appear stationary if illuminated solely by a fluorescent lamp. It also causes problems for video recording as there can be a 'beat effect' between the periodic reading of a camera's sensor and the fluctuations in intensity of the fluorescent lamp.


Incandescent lamps, due to the thermal inertia of their element, fluctuate to a lesser extent. This is also less of a problem with compact fluorescents, since they multiply the line frequency to levels that are not visible. Installations can reduce the stroboscope effect by using lead-lag ballasts, by operating the lamps on different phases of a polyphase power supply, or by use of electronic ballasts.
Electronic ballasts do not produce light flicker, since the phosphor persistence is longer than a half cycle of the higher operation frequency.

The non-visible 100–120 Hz flicker from fluorescent tubes powered by magnetic ballasts is associated with headaches and eyestrain. Individuals with high flicker fusion threshold are particularly affected by magnetic ballasts: their EEG alpha waves are markedly attenuated and they perform office tasks with greater speed and decreased accuracy. The problems are not observed with electronic ballasts.[6] Ordinary people have better reading performance using high-frequency (20–60 kHz) electronic ballasts than magnetic ballasts.[7]

The flicker of fluorescent lamps, even with magnetic ballasts, is so rapid that it is unlikely to present a hazard to individuals with epilepsy.[8] Early studies suspected a relationship between the flickering of fluorescent lamps with magnetic ballasts and repetitive movement in autistic children.[9] However, these studies had interpretive problems[10] and have not been replicated.


Dimming of fluorescent lamps


Unless specifically designed and approved to accommodate dimming, most fluorescent light fixtures cannot be connected to a standard dimmer switch used for incandescent lamps. Two effects are responsible for this: the waveshape of the voltage emitted by a standard phase-control dimmer interacts badly with many ballasts and it becomes difficult to sustain an arc in the fluorescent tube at low power levels. Many installations require 4-pin fluorescent lamps and compatible controllers for successful fluorescent dimming; these systems tend to keep the cathodes of the fluorescent tube fully heated even as the arc current is reduced, promoting easy thermionic emission of electrons into the arc stream.

Disposal and recycling of fluorescent lamps

The disposal of phosphor and particularly the mercury in the tubes is an environmental issue. (Incandescent lamps do not contain mercury.)


For large commercial or industrial users of fluorescent lights, recycling services are available in many nations, and may be required by regulation. In some areas, recycling is also available to consumers. The need for a recycling infrastructure is an issue with instituting proposed bans of incandescent bulbs.

 

 

 

 

 

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