The nitty-gritty details regarding downlights and linear luminaires
By Norma Frank
When upgrading the lighting in an existing building, the owner must decide whether to retrofit or replace the luminaires. Retrofit can be a simple and cost-effective path, but it imposes risks stemming from installing LED technology in luminaires and ballasts designed for a different light source.
In a NALMCO webinar about maintenance broadcast last year by the IES, NALMCO President Chris Frank covered the nitty-gritty of LED retrofits in a key section contributed by GE Senior Lighting Application Specialist Sri Rahm. As this nitty-gritty has major implications, it bears repeating in this column.
Summarized below, the considerations cover two popular retrofit targets: downlights and linear luminaires. Of course, Mr. Rahm’s recommendations are provided for educational purposes only; for more information, contact the appropriate manufacturer.
Screw- or plug-in LED downlight retrofit lamps promise up to 80% energy savings. These luminaires often house 120-V halogen PAR or A-line lamps, though self-ballasted CFL or HID lamps or plug-in CFLs may be found. Some luminaires may include a medium screw socket but one that connects to a ballast.
The lowest-risk path is to simply replace the luminaire with one properly designed for thermal management and optics required by the LED source. If retrofit is chosen, Mr. Rahm said there are four key potential risks:
- Improper matching. First is improper matching of the lamp to the luminaire. Just because a lamp screws into the socket and makes electrical contact does not mean that contact is electrically sound. While the majority of screw-base LED lamps are designed to operate on 120 volts, the socket may have 277 volts or an HID ballast behind it. The result of improper matching may be performance failure, which can take days to reveal.
- Excessive temperatures. Another potential issue is excessive operating temperatures that can reduce light output or the useful life of driver electronics. These temperatures may result from the downlight having inadequate air circulation. Mr. Rahm recommended either avoiding retrofit of very tight cans or enclosed luminaires, or verifying that based on the lamp’s wattage, the downlight is thermally appropriate for it.
- Incompatibility with dimmers. The third issue is incompatibility with dimmers. While the LED may promise to be dimmable, it may use a different dimming method such as 0-10-V or forward- or reverse-phasecontrol dimming. For good performance, one must verify the exact lamp-dimmer pairing is compatible. One way to accomplish this is to ensure both the lamp and the dimmer use the same dimming method and are otherwise designed to the NEMA SSL-7A standard.
- Quality. Finally, as with any retrofit, good quality is essential. If a retrofit lamp is a low-quality product, it may provide low-quality performance and fail prematurely.
Tubular LED (TLED) lamps are growing in popularity as a replacement for fluorescent T12, T8 and T5/T5HO lamps to generate up to 40%-plus energy savings. This option is particularly well suited to projects where the owner has a limited budget, wants the same space appearance, or is spot relamping a large facility.
The lamp houses the light source, optics and heat sinking. As they are directional, the lamp has an “up” and “down,” and must be installed properly so that the light is emitted toward the task plane.
Additionally, the lamp may be configured as UL Type A, B or C. Type A lamps are plug-and-play or drop-in lamps that operate on the existing ballast. Type B single- or double-ended lamps bypass the ballast and operate on an internal driver. Type C lamps operate on an external driver. Hybrid designs such as AB and AC are also available, which install as Type A but can then be configured for a different mode of operation after the ballast fails.
Mr. Rahm noted four potential risks related to these retrofits:
- Lamp choice. First, is choosing the wrong lamp for the job. The TLED replacement must not only save energy but maintain or improve lighting quality. The new lamp should be verified as able to produce the light output, visual comfort and distribution required by the application.
- Shock hazard. A second risk is TLED lamps can pose a shock hazard and therefore must be handled with more caution than fluorescent lamps. Mr. Rahm recommended turning OFF power to the luminaire during installation. If this isn’t done, when inserting one end into the socket, assume the other end has become electrically hot.
- Lamp/ballast compatibility. Another consideration is if a Type A lamp is used, the lamp and ballast must be specifically rated as compatible, or else risk poor performance and even catastrophic failure. It pays to confirm interoperability before committing to a big installation. Also be sure to check all the luminaire types that are installed. For example, emergency luminaires may have different ballasts installed. Further, be sure to inspect the existing luminaires to determine all components that may require replacing. If the existing ballasts are older, consider changing them out as well, which could be dedicated LED ballasts that are unable to operate fluorescent lamps. Existing sockets may also need replacing for good contact.
- Labeling and training. Finally, the project will require proper luminaire labeling and maintenance personnel training. If any TLED lamp type other than A is installed, labeling must be affixed to the luminaire to warn personnel not to install fluorescent lamps. With Type B lamps, line voltage is fed to the sockets, presenting the hazard of catastrophic failure if re-installing fluorescent lamps in the future. Mr. Rahm pointed out that this issue is compounded when using Type AB lamps, which install as Type A but then can be rewired for Type B when the ballast fails. This can result in TLED lamps in the same space, with some operating as Type A and others as Type B. For this reason, it’s essential that any rewiring and cautions be clearly displayed on a new luminaire label, and that maintenance personnel are trained to read and understand all safety labeling on the luminaire.
Type C has its own issues, as the lamp and driver are typically matched, which can be problematic if maintenance personnel try to operate another manufacturer’s lamp on the driver. Additionally, as LED technology advances, lamp operating currents and voltages may change, requiring good documentation. Further to this, documentation should include driver current, voltage and date of installation. Some owners may find it beneficial to purchase spare drivers as replacement stock as insurance against the possibility equivalent product will not be readily available.
Devil in the Details
Retrofitting recessed downlights and linear luminaires with LED lamps can provide a simple and cost-effective path to energy cost savings, but care should be taken to mitigate any associated risks.
Proper product selection, installation and documentation/labeling will ensure that maintenance proceeds smoothly and safely, and focuses on preserving system life rather than addressing installation issues.