LEDs have been extensively utilized for lighting since 2009. Prior to that, incandescent and gas-discharge lamps (incl. fluorescent lamps) with screw and pin bases were used for over a century. Numerous fixtures are designed for lamps with E17 and E26 sockets (in the US, E14 and E27 sockets in Europe), as well as G13. For these, so-called retrofits are available—LED lamps that can be installed in place of a traditional lamp without needing to modify the fixture (with minimal mods for G13 sockets). On a household level, retrofits are often referred to as just "lamps," but from a lighting engineering perspective, they are fully functional fixtures that include a driver, light source, and optical system.
Despite the availability of LED fixtures, people often still buy new fixtures initially designed for regular lamps just to install retrofits into them. Let’s explore the pros and cons of this methodology.
Disadvantages of Retrofits
For a retrofit to be installed seamlessly in place of an incandescent or fluorescent lamp, it must fit within certain size restrictions. This necessitates using simplified driver designs and smaller electronic components. The smaller the components, the more susceptible they are to voltage spikes in the grid. A diminutive capacitor size usually means low capacity. Size limitations for the heat sink and the close placement of the driver to the light source lead to overheating of electronic components. Consequently, compared to fully integrated LED fixtures, retrofits have a shorter lifespan, are more prone to failure from voltage spikes, and have higher flux pulsations.
Another issue is that the light distribution of a retrofit is often different from that of a regular lamp. This can affect the uniformity of the lighting.
Why Are Retrofits Installed in New Fixtures?
Innovative design solutions often originate from small companies lacking expertise in electronics. So, they create fixtures with the electrical side including just a plug, power cord, switch, and a standard socket. Major lighting manufacturers, on the other hand, take this approach to fulfill mass market demands. People often rely on their past experiences and are skeptical about fixtures that do not allow for lamp replacement.
Low-Voltage Lamp Fixtures
The above-mentioned disadvantages apply to retrofits for 120V (US, 230V for European countries) AC voltage. However, there are also fixtures designed for halogen lamps with a 12V AC power supply, usually with G4 or G5.3 sockets. When retrofits are installed in such fixtures, the step-down transformer is replaced with a power supply that provides 12V DC. Since the power supply is DC, smoothing out flicker is unnecessary. Low voltage allows for high reliability, even with miniature electronic components. Consequently, fixtures with retrofits replacing halogen lamps at 12 VDC have superior technical characteristics. Unfortunately, halogen lamps with 12V DC are rarely used in stationary fixtures, which limits the impact of this method for transitioning to LED lighting.
