The workhorse luminaire of offices, schools and hospitals, sized to lay into standard ceiling grids at 2x4, 2x2 or 1x4 feet, or 600 x 600 mm in metric markets. The name blends trough and coffer. Fluorescent troffers hold tubes behind prismatic lenses or parabolic louvers; LED versions use edge-lit or direct-lit panels and center-basket designs.
Replace the 2x4 parabolic troffers with the center-basket LED ones, same grid, half the wattage.
Also heard as
- lay-in
- 2x4
- 2x2
Related terms
Luminaire
The whole light fixture as one product: light source, optics, housing, driver or ballast and power connection.
UGR
Unified Glare Rating: a calculated index of discomfort glare from interior luminaires, where lower numbers mean less glare.
Ballast
The device that starts and limits current to fluorescent and HID lamps, which would otherwise draw unlimited current.
Driver
The electronic power supply that converts line voltage into the regulated current or voltage an LED needs.