Philips TL5 HE

High colour rendering T5 fluorescent linear lamps TL5 HE (High Efficiency) Features Triphosphor internal coating outer bulb G5 bi-pin base (also known as miniature bipin) Color rendering index Ra of 85 Typical lifetime of 24.000 hours Luminous efficacy of 86 to 94 lumens/watt Different white appearances (from 2700 to 6500 K colour temperature) Universal operating position Lamp control gear Requires external gear and appropriate wiring: Compatible only with high-frequency electronic ballast

Best retro purpose

Flourescent lamps are the most popular and widely used lighting source. Still widely used in most indoor environments due to their high effciency and very good colour reproduction, flourescent lamp stocks and availability is still high. Millions of these lamps have been produced worldwide for decades. They are clearly suited for indoor lighting especially when paired with an electronic ballast that eliminates flicker and also increases system efficiency. Due to the great variety of lamps, there are some suggestions for use. Most flourescent lamps operate well at 25 degrees Celsius ambient temperature and have very low light output in freezing or below freezing environments but hot environments also reduce efficiency.

TL5 lamps are a mixed back. On the one side, they were the most efficient fluorescent lamps but fixtures are quite rare, as the lamp was not popular or cheap. There is nothing special or nostalgic in the lamp itself and the slender lamp tube is better suited for accent or directional lights. Due to the fact that there were two separate very different lamp classes, there is even more confusion about estimating the light level and desired effect. HE stands for High efficiency, which means slightly higher light output per meter than typical Super 80 class fluorescent lamps. HO stands for "high output" and means a much higher light output per meter with a corresponding increase in heat disipation but relatively energy efficiency. Theoretically, any lamp can be suitable but high output lamps are slightly more attractive for outdoor or higher luminance requirements.

Super 80 lamps have been the most popular lamp type since the early 2000s and up to the present (2021). They may still be found new, are cheap and have very good performance. This lamp type is especially suited for areas that require a large amount of light. Due to the lamp's size and luminous flux, they are best suited for floodlighting although they can be just as well used for general lighting in any conditions. These lamps have a tendency of over saturating objects colour appearance which may be a desired or undesired side effect. Any interior can be well and pleasantly light with these lamps although foliage, plants, flowers are very well showcased.

Understanding manufacturer data

Lamp light output is always measured in lumens. This is a way of measuring by averaging light output at a distance of 1 meter in an integrating sphere. This was carried out in lab environments and this information was mentioned in lamp datasheets and catalogues. While this information is accurate it should be considered only across similar lamp types.

Lamp life is presented in thousands of hours. It does not point at a specific moment when an installed lamp will not operate anymore but a statistical point at which some of the lamps may not operate, giving a rough estimate of useful life.

Ra8 colour rendering index, or simply colour rendering index is a way of expressing the typical colour rendering capability of a lamp. While it may be non-intuitive this is a computed average of brightness of certain coloured samples that are light by the lamp. The brighter they are, the more efficient is the lamp in this task. Most lamps do not have a continuous colour spectra so only some specific colours might look very bright and others look very dull. Colour samples are not intense reds, greens and blues but intermediately vivid colours that are focused on human skin colours and some fabrics or surfaces, meaning that a only very high colour rendering indexes are desirable for indoor home lighting. Sun light renders colours almost perfectly, having a value of 100 while typical lamps have a rendering index between 50 and 80, a good value being above 80 and a poor one below 50.

Colour temperature is another important detail. The value is presented in Kelvins and follows a theory that boils down to the fact that light can be produced by heating a metal up to a specific temperature. A camp fire releases light as the flame reaches around 1500-2000 degrees Celsius and a slightly higher value expressed in Kelvin. The designation is warm white for a value of around 2700 Kelvin, natural white with a value of around 3200-3500 Kelvin, cool white for a value of around 4000-4500 Kelvin, daylight for a value between 5000 and 5500 Kelvin, and cool daylight for a value above 6000-6500 Kelvin. There are cultural preferences that make some warm colour temperatures preferred in colder climates and cool colour temperatures in warmer climates. The most popular home lighting worldwide is mostly warm white, due to a comfortable, pleasant atmosphere that is close to the old incandescent lamp.

Technical details

Designation	Base	Lamp wattage	Luminous flux	Colour appearance	Colour Temperature	Colour Rendering Index (Ra8)	Life (to 50% failures)
MASTER TL5 HE 14W/827	G5	14 W	1200 lm	Incandescent White	2700 K	85	24000 hours
MASTER TL5 HE 14W/830	G5	14 W	1200 lm	Warm White	3000 K	85	24000 hours
MASTER TL5 HE 14W/835	G5	14 W	1200 lm	(Neutral) White	3500 K	85	24000 hours
MASTER TL5 HE 14W/840	G5	14 W	1200 lm	Cool White	4000 K	85	24000 hours
MASTER TL5 HE 14W/850	G5	14 W	1100 lm	Daylight	6500 K	85	24000 hours
MASTER TL5 HE 14W/865	G5	14 W	1100 lm	Cool Daylight	6500 K	85	24000 hours
MASTER TL5 HE 21W/827	G5	21 W	1900 lm	Incandescent White	2700 K	85	24000 hours
MASTER TL5 HE 21W/830	G5	21 W	1900 lm	Warm White	3000 K	85	24000 hours
MASTER TL5 HE 21W/835	G5	21 W	1900 lm	(Neutral) White	3500 K	85	24000 hours
MASTER TL5 HE 21W/840	G5	21 W	1900 lm	Cool White	4000 K	85	24000 hours
MASTER TL5 HE 21W/865	G5	21 W	1750 lm	Cool Daylight	6500 K	85	24000 hours
MASTER TL5 HE 28W/827	G5	28 W	2600 lm	Incandescent White	2700 K	85	24000 hours
MASTER TL5 HE 28W/830	G5	28 W	2600 lm	Warm White	3000 K	85	24000 hours
MASTER TL5 HE 28W/835	G5	28 W	2600 lm	(Neutral) White	3500 K	85	24000 hours
MASTER TL5 HE 28W/840	G5	28 W	2600 lm	Cool White	4000 K	85	24000 hours
MASTER TL5 HE 28W/850	G5	28 W	2400 lm	Daylight	5000 K	85	24000 hours
MASTER TL5 HE 28W/865	G5	28 W	2400 lm	Cool Daylight	6500 K	85	24000 hours
MASTER TL5 HE 35W/827	G5	35 W	3300 lm	Incandescent White	2700 K	85	24000 hours
MASTER TL5 HE 35W/830	G5	35 W	3300 lm	Warm White	3000 K	85	24000 hours
MASTER TL5 HE 35W/835	G5	35 W	3300 lm	(Neutral) White	3500 K	85	24000 hours
MASTER TL5 HE 35W/840	G5	35 W	3300 lm	Cool White	4000 K	85	24000 hours
MASTER TL5 HE 35W/865	G5	35 W	3100 lm	Cool Daylight	6500 K	85	24000 hours

Notes:

• Neutral white colour appearance lamps were seldomly used as the 3000, 4000, 6500 K lamps offered satisfactory variety; the 3500 K lamps or neutral white were traditionally popular in the United Kingdom;

Greatest features & flaws

Features	Flaws
Moderate glare risk, uniform lighting	Very large lamps and fixtures
Highest efficiency, longest life, very good colour rendering	Very fragile construction
Highly suited for directional light	Sensitive to operating temperature
Quick lamp start and restart, inexpensive	Requires lamp gear

Review

Until the advent of advanced LED lamps, flourescent lamps were unsurpassed in terms of efficiency and lighting comfort. The lamp's quick restart, good light stability even on conventional, magnetic gear, and reasonably simple wiring made them easy to service although the lamp bi-pin connection was prone to failure due to lamp's handling as well as normal wear, the system was reasonably easy to repair and failures were quite obvious.

TL5 lamps are more of a specialty product as they were not highly popular. Some large retailers and office building administrator used them in most installations, however, typical office, residential, commercial and especially industrial premises remained on standard TL-D or T8 lamps fixtures even as late as 2008. This was especially due to cost but also due to the the inconvenience of retraining employees to install and maintain efficiently a different lamp technology. There was also the issue of maintaining incompatible inventory for another separate installation that was not a very major improvement compared with the switch from TL to TL-D lamps or from standard TL-D lamps to TL-D Super 80. All these were major reasons for avoiding newer TL5 installations unless ultimate efficiency and no cost concern were goals at that specific time.

TL5 Super 80 lamps, even if they were not called that way they were still comparable to TL-D Super 80 lamps, were advantageous due to high luminous output and low price. The wide array of colour temperatures caters to any application. Warm colours or more active daylight ambiances can be created easily. The lamps' very good stability and output ensures a long service life with minimal degradation. This was especially important compared with TL-D Standard lamps, as the older lamp type aged much quicker and had lower light output along with colour reproduction. Requirements for higher than 80 Ra colour rendering index in Europe made the lamps extremely popular and even made them as cheap or even cheaper than TL-D standard lamps due to volumes, marketing and economies of scale. On the other side, if TL-D Super 80 lamps were already retrofit or retrofitable on an existing installation, there was little justification for new TL5 lamps. Even presently, prospects for retrofits are still good, with LED tubes being able to replace older flourescent lamps on TL-D or T8 installations. Cost-wise, TL5 lamps were most advantageous when compared with the prospect of replacing magnetic or inductive ballast TL-D or T8 lamps, as TL5 lamp type already mandated high frequency electronic lamp gears which bring much increased energy efficiency and comfort.

Operation

All lamps require the same lamp gear type as there are no magnetic ballasts released as on older flourescent lamp technology. An electronic lamp gear eliminates flicker and increase the lamp's service life. Note that some cheap electronic ballasts do not actually offer preheating and start instantly the lamp, reducing the lamp's useful life. Preheating of lamps is assumed if there is any mention of a 0.5second duration on the electronic ballast label or the word preheating. Most world manufacturers released electronic control gear and some products even allowed variable dimming using special protocols.

While a dimmed flourescent lamp is not as efficient as full power operation, there were and are some environments were such flexibility is appreciated. Note that starting and operating dimmed lamps is less reliable and the temperature balance and optimum operation conditions slightly deviate in these circumstances. Overpowering a lamp is possible but it is not advised. While Super 80 lamps are best suited for these circumstance that increase light output with some reduction in efficiency and service lamps, operation in such conditions stresses the lamp. Note that operating in cold environments, as a deviation from ideal conditions, reduces lamp current and power, making the lamp slightly unstable and dim.

Suitability

TL5 lamps were mostly advantageous in recessed or fully enclosed lamp fixtures as the lamp dimension meant that optimal operating temperatures were slightly higher than on typical fluorescent lamps. Just as well, small luminaires could more easily have better optical control, meaning that the light output could be more efficiently directed were matters, increasing overall system efficiency. This meant that indoor retail or office lighting fixtures were probably the most successful application as residential spaces were appreciated higher if a slightly harsher and a more alluring, diffuse, light was cast on the area. Due to different lamp lengths and light outputs, replacing T8 or TL-D standard fixtures was quite difficult and rarely carried out.

History

Flourescent lamps were an evolution of clear mercury vapour lamps. Development followed two avenues to increase efficiency, low pressure mercury vapour discharge and high pressure mercury discharge. High pressure mercury discharge created more useful light but the same deficit of no red and orange light was present so the light was still unsatisfactory. Low pressure mercury discharge is very efficient but not in outputting visible light, it is on UV-light emission. This UV-light is useless if it cannot be converted to visible light.

Flourescent powders were developed to convert UV-light into visible light. Some of these powders were capable of emitting light at some wavelengths, making specific colours to be cast around but they had to be quite resistant to UV-light and efficient. This meant that some time passed until the advent of halophosphate based colours that made possible the first daylight T12 flourescent lamps, around late 1930s. This was a major achievement as such lamps had the capability of directly competing with incandescent lamps and offer better efficiency and longer life.

Subsequent developments improved lamp life and created a wide variety of flourescent powders that cast white light with different colour appearances from warm and neutral to cold and daylight. Higher and lower power lamps were created and standardization established. The preferred lamp gear turned from incandescent ballasting or mixed light to magnetic or reactive ballasts, which improved system efficiency. In the late 1970s, following requirements for higher energy efficiency due to the world oil crisis of 1973, there were major advances in technology.

The advent of high efficiency tri-band or tri-phosphorous lamps was the most important landmark. Successful development of flourescent powders that had peak UV to visible light conversion at blue, red, and green colours with peaks near the ideal wavelengths made it possible to release lamps with specific colour appearances. This high energy in light conversion was complemented by changes in the lamps gas's fill from argon to Krypton, reducing thermal losses with a slight increase in operating voltage and starting voltage. The TL5 lamp technology was an improvement on TL-D types based on the existing TL Mini lamp range. Of course, major gas fill, mercury vapor operating pressures had to determined.

Due to the lamp's requirement of a different gas fill and diameter to length ratio meant that conventional, inductive, lamp gears were not optimal and newer, electronic lamp gears, had to be specified and used. This is the secret that allowed tremendous lamp performance improvements compared with similar TL-D lamps on standard gears. It should be noted, however, that retrofiting electronic lamp gears on any standard TL-D flourescent lamp automatically improves efficiency and reduces lamp power by around 15%, and this is not specified in any chart or comparison pertaining on TL-D vs. TL5 lamps. All this meant that benefits of TL5 technology was around less than 10% when comparing the best lamp gear and technology on the TL5 and TL-D or T8 format. This meant that only around mid 2000s TL5 lamps were reasonably competitive when taking into account also improved luminaires that could not be specified on the TL-D format or when size, weight or warehousing space were important.

Manufacturing specificities

Philips flourescent lamps had very good manufacturing tolerances and the lamp's construction along with flourescent powder quality made reliable, predictable operation entirely ensured. Other world manufacturers were capable of similar performance. However, some slight differences were noticeable. For instance, Philips had slightly less powerful red phosphorus than Osram, which means that entirely equivalent lamps from both manufacturers had slightly different colour appearance. On the other side, Chinese branded lamps were much inferior in terms of flourescent powder quality and colour reproduction as well as efficiency and service life.