Cree estimated that there are around 2 billion linear fluorescent sockets installed around the globe that can be retrofitted with LED-based tubes for energy and maintenance savings and better light quality leading to the introduction of the UR Series LED Upgrade Kit. But Cree sought to eliminate concerns over other retrofit tubes in terms of whether LED tubes can be safely mounted in existing fluorescent sockets that are connected to the AC line. The Cree tubes are attached using self-tapping screws and connected to an external driver.
The most common LED tubes on the market integrate a driver in each tube and either connect to the existing fluorescent ballast, or more commonly, require the electrical disconnection of the ballast and the direct connection of AC power to the sockets. While many retrofits have been accomplished using such technology, many in the industry have questioned the safety of such an approach. Concerns range from whether the old sockets in a troffer can safely hold a heavier LED tube to dangers associated with exposing AC power in the sockets.
Cree's approach may seem a bit more complex in terms of installation scenario, but should eliminate safety concerns. Installers will first replace the existing ballast with an LED driver. Then the tubes are mounted using the self-tapping screws driven into the troffer sheet metal through a pair of clips. The clips even have a magnet on the back side that can temporarily hold the tubes in place leaving the installer with hands free to drive the screws. The company has produced a video (see below) that shows the entire process.
"The new Cree UR Series LED Upgrade Kit is a real breakthrough," said Bruce Curtis, president of Pearl Street LED Lighting Systems. "The use of magnetic mounting clips on the lightbars and the simple quick connects from the driver make this the fastest LED upgrade kit we’ve seen. We tested both lensed and parabolic fixtures replacing three T8 lamps with the Cree UR2 upgrade kit and not only maintained our light levels but saved over 50% in energy. This is an LED retrofit kit that actually works."
Broader beam spread
There are other advantages to the Cree approach according to product portfolio manager Jeff Hungarter. He said the fact that Cree didn't have to include a driver in the tube allowed for more lens surface and a broader light distribution. The UR offers a 220° beam spread whereas most LED tubes are in the 120° range according to Hungarter. The broader beam means the UR tubes are capable of a one-for-one replacement of fluorescent tubes — a capability in which LED tubes have struggled according to testing such as the US Department of Energy Caliper tests.
With the UR Series, Cree is primarily targeting the parabolic and lensed troffer sub segments that Hungarter said makes up about half of the fluorescent installed base. The tubes can also be used in some wrap, strip, industrial, and volumetric-basket applications.
The UR Series delivers efficacy of 102 lm/W including the driver. That allows the upgrade kit to hit Cree's target of 90 lm/W out of all fixture types since some induce additional optical losses through lenses and/or reflectors.
Cree's product designers undertook the project knowing that the kit would need to deliver the efficacy to be able to match fluorescent light output. Hungarter said, "We needed to hit 4000 lm to have a product that fits in 90% of the 4-ft fixture market."
Payback will vary based on each installation scenario, but Cree said in a one-for-one tube retrofit of standard 4-ft 32W fixtures that 1.5 years would be typical without rebates. Hungarter said that in parabolic retrofits a one-for-one replacement is generally needed because light must fill each reflector cell. He said that in some lens-based troffers, customers may be able to replace three tubes with two of the UR series, perhaps resulting in a slight but acceptable decrease in light output, but also in faster payback.
At launch Cree will offer a total of eight models – four 2-ft and four 4-ft versions. In each length, the company will offer a choice of 3000K or 4000K CCTs, and either two or three lamps. All of the lamps have a CRI above 80 and come with a seven year warranty.