LED Tube Lights

An LED tube light is a type of LED retrofit lamp designed to replace traditional linear fluorescent lamps in existing lighting fixtures. These LED tubes are engineered to fit into the same sockets as fluorescent tubes, effectively converting fixtures originally designed for fluorescent lighting into more energy-efficient and longer-lasting LED systems. This retrofit capability simplifies the process of upgrading lighting systems in various settings. LED tubes are specifically developed to address the need for retrofitting existing fixtures, offering a straightforward solution for transitioning to LED technology without the need for extensive modifications or replacements of entire lighting fixtures. They are compatible with a wide range of fixtures, including recessed troffers, wraparound fixtures, linear high bay lights, shop lights, and vapor-tight fixtures. Despite the growing trend towards designing LED luminaires as integrated performance systems, LED tubes remain widely used in commercial, industrial, and institutional buildings. These buildings include offices, hospitals, schools, shopping centers, retail establishments, warehouses, manufacturing facilities, and assembly plants. LED tubes serve as the "workhorse" in such settings, providing energy-efficient lighting solutions while leveraging existing infrastructure and reducing installation costs.

LED tube lights inherit the form factor and lamp base of linear fluorescent lamps, making them compatible with existing fixtures. Historically, fluorescent lamps came in two common sizes: T12 and T8. T12 lamps, 1.5 inches (3.81 cm) in diameter, were prevalent until around 1980. The introduction of T8 lamps, with a diameter of 1 inch, led to their widespread adoption due to their increased efficiency and brightness. T8 lamps utilize the G13 medium bi-pin base, making them interchangeable with T12 lamps. This interchangeability, combined with their superior performance, established T8 lamps as the dominant linear lighting source for new construction and renovation projects. They are available in lengths of 2, 3, 4, and 5 feet (or 600 mm, 900 mm, 1200 mm, and 1500 mm). When discussing LED tube lights, the term often refers to T8 LED lamps by default, although LED replacements for T5 fluorescent lamps also exist. T5 LED lamps, 5/8 inch or 16 mm in diameter, differ from T8 LED tubes in both size and pin spacing. The shorter length and the use of different pin spacing on the bases (T5 uses G5 miniature bi-pin bases) prevent interchangeability between T5 and T8 LED lamps.

A fluorescent light fixture traditionally consists of three main components: the housing, an electronic ballast, and one or more fluorescent tubes. Transitioning these fixtures to use LED technology, particularly in T8 setups, necessitates careful attention to the existing ballast's functionality. This adaptation process is crucial to successfully switch from fluorescent to LED lighting while using the original fixture structures. The ballast in a fluorescent fixture plays a crucial role; it regulates the current that passes through the lamp, which is vital for starting and safely operating the lamp. This regulation is necessary to maintain appropriate current levels, preventing it from rising uncontrollably due to the negative resistance characteristic of fluorescent tubes, which can otherwise lead to electrical hazards. There are several types of electronic ballasts, each suited to different needs. Instant-start ballasts use a high voltage to ignite the lamp without preheating the electrodes, offering the most energy efficiency and are widely used due to their operational benefits. Rapid-start ballasts heat the electrodes simultaneously while applying voltage, which is beneficial for environments where lamps are frequently turned on and off, thereby extending the lifespan of the lamps. The most sophisticated, programmed-start ballasts, preheat the cathodes before applying a higher starting voltage, optimizing the lamp's lifespan without significantly compromising on energy efficiency.

When retrofitting to LED, the existing ballast configuration becomes a significant consideration. Options include bypassing the ballast, which involves technical rewiring by a qualified electrician and ensures that LED tubes are not constrained or damaged by incompatible ballasts. Alternatively, ballast-compatible LED tubes can be used; these are designed to operate with the fluorescent ballast and are popular for their simplicity and cost-effectiveness, as they reduce the complexity and cost of installation. However, potential issues can arise from using existing ballasts with LED tubes, such as electrical incompatibilities that might affect the safety, efficiency, and reliability of the lighting system. Another important consideration in retrofitting is the compatibility of lamp holders. Shunted lamp holders, used with instant-start ballasts, connect both pins together, while non-shunted lamp holders, used with rapid-start ballasts, allow for separate connections for each pin, facilitating independent control and power flow. LED tubes typically require non-shunted lamp holders, aligning more closely with rapid-start ballast configurations.

Upgrading lighting systems, particularly transitioning from fluorescent to LED technologies, requires a comprehensive assessment that includes financial, installation, operational, and maintenance considerations. One of the critical decisions in this process involves the handling of the existing fluorescent ballasts, which influences not only the initial installation costs but also impacts the long-term energy efficiency, electrical safety, functionality, and maintenance needs of the retrofit. There are four main types of LED tube lights categorized by their compatibility with existing ballasts and their driver integration. Type A (ballast compatible) LED tubes are designed to work directly with the existing fluorescent ballasts. This option is appealing because it allows for easy installation without significant rewiring—essentially a plug-and-play solution. However, the energy efficiency and performance of Type A tubes depend heavily on the compatibility with the old ballast, and potential mismatches can lead to reduced performance or increased maintenance. Type B (ballast bypass) LED tubes require the existing ballast to be removed or bypassed, which involves some rewiring. While this requires more effort and cost upfront, it eliminates dependency on the old ballasts, often resulting in better energy efficiency and fewer maintenance issues since the LED tube operates directly off the line voltage with its internal driver. This option also reduces the points of failure within the lighting system. Type C (external driver) LED tubes do not use the existing ballast and instead are powered by an external driver. This setup allows for optimal energy efficiency and performance control because the external driver can be finely tuned to the specific needs of the LED tubes. Installation is more complex and costly as it involves removing the existing ballast and setting up the external driver, but it often results in the best overall functionality and lowest running costs. Dual Mode (Type A + Type B) LED tube lights offer flexibility. They can operate with or without a ballast, which is beneficial during transitional phases or in environments where future upgrades might necessitate a switch from one mode to the other without replacing the tubes. This category provides a versatile solution that can adapt to various electrical setups and changing future needs. The choice among these options should align with the specific goals and constraints of the lighting upgrade project, taking into account the current infrastructure, budgetary considerations, and desired operational outcomes.

LED tube lights are available in two primary housing types: hybrid aluminum/plastic and full plastic/glass constructions. In hybrid aluminum/plastic housing, the tube comprises an exposed aluminum housing, often D-shaped, integrated with a polycarbonate lens to form a tubular structure. This design incorporates an extruded aluminum housing with a cavity for the driver circuit, insulated to prevent contact with metal parts. A linear LED module, consisting of SMD LED packages mounted on a metal-core printed circuit board (MCPCB), attaches to the bottom of the aluminum housing. The aluminum housing's bottom can be slotted to receive the LED module, with angled sides shaping the beam and providing optical reflection. Conversely, LED tubes with full plastic or glass housing feature a built-in aluminum plate to hold the linear LED module and facilitate heat dissipation. In this design, the driver circuit is side-mounted into one of the end caps, which are longer than those used in hybrid constructions. The aluminum housing of the hybrid type efficiently dissipates heat from the LEDs, enhancing convective heat transfer due to its exposed surface area. However, the proximity of the driver to the heat source may stress it, potentially leading to issues such as light flickering or compromised isolation ability due to degradation of electrolytic capacitors used in LED drivers. On the other hand, full plastic or glass tubes with an internal end-cap driver offer improved thermal management by relocating the driver away from the LEDs, reducing thermal stress and enhancing electrical insulation. However, the enclosed housing limits convective heat transfer, potentially causing bending or warping, especially in longer lengths. Glass constructions provide rigidity, often coated with PET for protective purposes. Depending on the application, the lens may be frosted or clear, with frosted lenses aiding in uniform light distribution but resulting in some optical loss, while clear lenses offer higher optical efficiency but can be visually harsh. The beam angle of LED tubes varies, and rotatable end caps allow for optical aiming as needed. Overall, the choice between housing types depends on factors such as thermal management requirements, optical preferences, and durability considerations for specific applications.

The design of an LED driver involves numerous factors, each impacting the performance, efficiency, and safety of the lighting system. These variables include cost, size, parts count, efficiency, power factor (PF), total harmonic distortion (THD), input voltage range, flicker, dimming capabilities, electromagnetic interference (EMI), and operating temperature. LED tubes typically operate using a constant current source, often configured as a switching mode power supply (SMPS). AC mains-connected LED drivers can be single-stage or two-stage designs. Single-stage LED drivers integrate power factor correction (PFC) and switching regulation into a single circuit, offering advantages such as reduced parts count, size, and cost, as well as improved circuit efficiency. However, they may not completely suppress the alternating waveform after rectification, leading to output current ripple and potential light flicker at twice the line frequency. In contrast, two-stage LED drivers feature separate PFC and DC-DC conversion circuits. While this design increases complexity, cost, and size, it offers benefits such as near-unity power factor, minimized ripple in the output current, and superior light output quality with less flicker, enabling smooth and deep dimming across various output current ranges. The DC-DC converter stage of LED drivers typically utilizes buck-boost, Cuk, SEPIC, or flyback topologies to generate the required DC power. However, the high-speed switching operation of these converters can produce electromagnetic emissions, necessitating additional EMI filtering for mitigation. Furthermore, for safety purposes, it is advisable to provide galvanic isolation between the input and output circuits. Low-cost LED drivers often lack galvanic isolation, posing potential electrical shock hazards in case of dielectric breakdown. In contrast, galvanically isolated LED drivers offer enhanced protection against transient voltages and power surges for both the driver and downstream components, ensuring safer operation and reliability. Thus, while LED driver design involves trade-offs between factors like cost, efficiency, and safety, prioritizing quality and safety features ensures optimal performance and longevity of LED lighting systems.

The mid-power LEDs employed in LED tubes exhibit variations in luminous efficacy, thermal performance, and color quality. Plastic-molded lead frame LED packages dominate the market due to their cost-effectiveness and high luminous efficacy. These LEDs typically consist of one or two small InGaN dies mounted onto a metal-plated lead frame within a polymer cavity filled with phosphor-mixed silicone. The reflective cavity and lead frame minimize light absorption, facilitating efficient photon extraction and yielding superior luminous efficacy compared to other LED package types. However, the thermal stability and photo resistance of the polymer used in these LEDs are limited, making them susceptible to thermal degradation and photo-oxidation, leading to discoloration—a primary cause of chromaticity shift and lumen depreciation in LEDs. To meet cost constraints, LED tube lights often utilize LED packages made of thermally unstable polymers and operate fewer LEDs at higher drive currents to achieve the required lumen output. In the absence of specific requirements, the spectral power distribution (SPD) of LEDs is typically optimized for high efficacy operation, compromising color quality. An acceptable color rendering index (CRI) of 80 is commonly targeted for applications with no special emphasis on color reproduction. The choice of correlated color temperature (CCT) may be influenced by application needs or efficacy requirements. Cool white LEDs, with minimal Stokes losses, offer higher luminous efficacy than neutral and warm white LEDs. To ensure uniform intensity and color consistency across the linear emitting surface and multiple fixtures, LEDs must be sorted or binned based on chromaticity, lumen output, and forward voltage. This sorting process helps achieve consistent performance and appearance in LED lighting systems.