task lights

8/16/2019 Task Lights

1/4

T a s k

L i g h t i n g

introduction

In the past, a tasklight could be anything from a draftsman’s lamp to a table lamp brought fromhome. It has typically been used to supplement the ambient lighting when it was not sufficient in aparticular area. Because it was not part of a larger plan, it did not always solve the lighting problem.Mounting the fixtures correctly or controlling glare was not always possible.

task / ambient systems Tasklights are now being used as a planned part of the overall electric lighting in what is called a‘task/ambient’ lighting system. This type of system utilizes an overall ambient light level between 30-50 footcandles from light fixtures that are either recessed in the ceiling, surface mounted or pendant hung. Additional light is provided at designated tasks by a tasklight. The tasklight can take many forms depending on the furniture configuration and the task. Mounting options, shielding andlamp type can all be specified. On the attached pages are some typical tasklight configurations witha brief description of how they are best used and how they are commonly misused.

Tasklights will either be fluorescent, standard incandescent or halogen incandescent. Gener-ally speaking, the fluorescent can provide more satisfactory service with its cooler operation, longer life and higher lumen output. An asymmetric reflector in the fixture helps direct light to the task andthe best reflector designs typically use a compact fluorescent source. The compact fluorescent source

also guarantees a high color rendition.Below: Typical tasklight configuration. Fixture is located directly in front of the user. Most of thelight is concentrated directly under the fixture which is typically not the task area. A small amount of light escapes at an angle which bounces light directly into the viewer’s eye, resulting in reflectedglare.


2/4

lighting design lab • 400 e pine st suite 100 • seattle wa 98122 • 206-325-97112

Above: If the task is primarily a horizontal paper task, 1 or 2 tasklights mounted to the side of the primary task area with asymmetric reflectors will cross light the desk. This cross lighting pattern will put the main beam of light in thetask area, not directly under the fixture. It also minimizes glare. If only one fixture is used, it should be mounted op-posite the side of the writing hand.

Below: If only one tasklight is used, it’s mounting type should be flexible enough to allow it to be moved to the op-posite side of the desk should the occupants change and have different writing hands. Common mounting types areC-clamps, grommets and weighted bases. Some fixtures have rail or standard mounts that can be used with furniture

systems.


3/4

lighting design lab • 400 e pine st suite 100 • seattle wa 98122 • 206-325-9711 3

Above: Even with an efficient source many tasklights are inefficient because so much of the light the lamp producesis trapped within the fixture. A solid box with a lens below is less efficient than an open box with an asymmetric re-flector. It is not uncommon that two 13 watt lamps produce considerably more light at the task than a single 40

watt fluorescent lamp in a box-type fixture even though the rated lumens are 1800 and 3000 respectively.

Below: The illustration is typical of tasklights that come with furniture systems. This is acceptable, only if it is light-ing a secondary work surface. The primary purpose of the lamps in this case is to cut the shadow created by the over-head storage bins. If it is a primary work surface, it should be set up as in the configuration to the right.


4/4

lighting design lab • 400 e pine st suite 100 • seattle wa 98122 • 206-325-97114

Below: When tasklighting around a computer, the tasklight should deliver light locally only to the area of the paper task. Any light that spills light onto the screen will reduce its legibility. A tasklight mounted to the copy stand is oneoption. For those who do not use copy stands, an adjustable tasklight with a small head and a parawedge louver canbe used to illuminate the task. The parawedge louver directs the light in a focused downward area with little spilllight. For an even more efficient system, an occupancy sensor that turns the tasklight off when the desk is unoccu-pied could be used.

sponsored by:

northwest energy efficiency alliance

seattle city light

u.s. department of energy

british columbia hydro

state of alaska

task lights

Documents