Dimming TLED and LED HID Replacement Lamps

When evaluating an existing lighting system, the owner can do nothing, something or everything. Doing nothing abandons operating cost savings. Doing something entails replacing lamps and installing some automatic controls. Doing everything involves installing a new lighting and control system.

As many owners opt for the “something” option, demand for LED replacement lamps continues to grow as the technology becomes increasingly viable. This necessitates understanding control options when planning LED lamp retrofits. Combined, these lighting and control solutions can deliver excellent energy savings while capitalizing on LED benefits such as instant-ON operation, long life, good color quality and universal operating position.

Tubular LED (TLED) lamps designed to replace linear fluorescents can generate up to 40+ percent energy savings, retrofit kits up to 50+. LED lamps designed to replace high-intensity discharge (HID) lamps can produce up to 50 percent energy savings. Incorporating controls, meanwhile, can result in an additional 24-38 percent average lighting energy savings while economizing on labor and maximizing utility rebates. Otherwise, the overriding retrofit goal should be to save energy while improving or maintaining lighting quality.

TLED lamps

TLED lamps are ideally suited to applications where the owner wants to maintain a similar space appearance, has a limited budget, or is spot relamping a large facility. The complete unit integrates the light source, optics and heat sinking. The majority are bi-pin T8 lamps designed to replace 2-ft., 4-ft. and U-bend T8 and T12 lamps, though some target T5 and T5HO lamps. While some lamps imitate the distribution and appearance of fluorescent lamps, the majority are directional.

TLED lamps are typically classified as UL Type A, B and C, all of which are compatible with automatic shutoff controls but vary in ease and compatibility with dimming control.

UL Type A: This “drop in” option operates on the existing ballast. Despite simple installation, it requires lamp-ballast compatibility, ballast losses reduce energy savings, and the ballast remains a point of failure.

Further, controllability is limited as it is recommended these lamps not be paired with fluorescent dimming ballasts.

UL Type B: This TLED lamp bypasses the ballast and operates using an internal driver that converts incoming AC to DC. The installer removes the ballast and brings line voltage to the sockets, necessitating safety labeling.

The lamp may be dimmable, though more difficult to implement, and should be specified with a high-quality driver to provide smooth, flicker-free dimming.

UL Type C: This TLED lamp bypasses the ballast and operates using an external driver. Low-voltage wiring connects the driver to the sockets. While requiring the most labor to install, Type C lamps offer high efficacy and multi-lamp driver operation.

These lamps typically provide easier implementation of and broader lighting control capabilities. As with Type B lamps, however, the lamp should be specified with a high-quality dimming driver.

Retrofit kits: This option packages the LED light engine assembly or lamp with optics and electrical components to produce a repeatable solution that enhances distribution and aesthetics, resulting in close to a new luminaire. The kits offer easier-to-implement and broader control capabilities.

LED HID replacement lamps

LED HID replacement lamps are ideally suited to applications where the owner has a limited budget or is spot relamping an existing facility, or where the luminaires are in relatively good condition. The majority of these lamps feature a “corncob” design that imitates the distribution of an HID lamp, while directional PAR lamps often feature a flat chip-on-board (COB) design. LED retrofit kits often feature a COB design and, along with new luminaires, are well suited to applications where the luminaires are older and in relatively poor condition.

LED HID replacement lamps are generally available in 30-400W to replace 50-1000W HID lamps. A common retrofit is replacing a 400W metal halide lamp with a 150W 17,000-lumen or 200W 21,000-lumen LED lamp. These products are available in 2000-5000K correlated color temperature (CCT) and a color rendering index (CRI) rating typically in the low 80s. The majority offer a 50,000-hour (L70) service life and are backed by a five- to 10-year warranty.

Similarly to a TLED lamp, LED HID lamps operate on an existing ballast or bypass it.

Ballast-driven LED HID replacement lamps operate on the existing ballast, offering a quick and easy “drop in” solution, though the ballast reduces energy savings by adding 40-60W of load, continues a point of failure, and requires confirmation of lamp-ballast compatibility.

Line-driven LED HID replacement lamps bypass the ballast and operate on line voltage. Energy savings may be higher but typically so is the labor cost, as the installer must bring line voltage to the socket.

These lamps are friendly with automatic shutoff strategies such as occupancy sensors, providing an advantage over HID lamps in that the LED lamp is instant ON. However, the majority of LED HID replacement lamps are not dimmable, limiting control options. If dimming desired, LED HID retrofit kits often package standard drivers featuring 0-10V leads able to connect with control systems.

A role for controls

Controls should be considered as part of any lighting upgrade as a way to increase energy cost savings, maximize rebates, more effectively modernize and add value to the lighting system, and gain flexibility. Because different LED replacement lamp retrofit options present varying degrees of controllability, be sure to include controllability as part of product selection and retrofit planning.