Control location. Lighting controls can be placed at the door, as are standard switches, or at the worker's desktop. A study conducted by the Lighting Research Center showed strong worker preference for the desktop location.
Controls with memory. The same study showed that workers who had to manually reset their preferred light level each time they turned on the lights were less likely to dim their lights than workers whose controls at start-up automatically returned lights to the preferred level.
Ballast flexibility. Dimming systems may come with ballasts included; they may be compatible with a specific ballast, or they may work with any ballast having a 0- to 10-volt control signal.
Handheld controls. At least two companies offer personal dimming systems with handheld wireless, infrared (IR) remote controllers, similar to the remotes that control TVs and VCRs in the home (Figure 1). The units enable fixtures to be controlled individually or in groups connected by low-voltage wiring. Most building codes allow low-voltage wiring to run above a suspended ceiling without conduit.
Figure 1: System for dimming lights with handheld infrared controller
This system enables users to dim lights with handheld wireless remote controllers similar to the remotes that control TVs and VCRs.
Direct-wired controls. Direct-wired controllers are also available. These devices use a small amount of power from the ballasts for remote control, so no batteries are required. In addition, the controllers do not depend on line of sight, as do IR controllers, making them easier for users to operate. Wiring is either free-run through the walls or colocated with communications wiring.
Desktop computer controls. At least one manufacturer offers a system through which users can control lighting levels via their personal computers (PCs). Each fixture is assigned an identification number and is linked to a local area network. Selected users, such as energy managers, can control all the fixtures from a PC for systemwide monitoring or energy savings programs.