Terminology

• Continuous run: joined fixtures forming one line with concealed joints
• Nominal length: 2 ft, 4 ft, 8 ft modules; exact-length or field-cut runs available
• Direct / indirect / direct-indirect: light downward, upward, or both
• Lumens per foot: output metric for linear products
• Lens types: frosted, opal, microprismatic, louvered; set glare and appearance
• UGR: unified glare rating for discomfort glare in workspaces
• Flange / flangeless (trimless): recessed edge visible or plastered flush
• Wall slot / grazer: linear products that wash or graze walls
• Power feed: location of electrical feed in a run; affects ceiling coordination

Standards

Ratings

• Efficacy: commercial LED luminaires commonly 90 to 110+ delivered lumens per watt; DLC listing for rebates
• Color: CCT 3000K to 4000K common in offices and schools; CRI 80 to 90+
• Lumen maintenance: L70 or L90 from LM-80 and TM-21
• Light loss factor: design for end-of-life lumens, 0.7 or less per IES guidance

Test standards

• UL 1598 and UL 8750
• IES LM-79, LM-80, TM-21
• DLC SSL technical requirements (V6.0 effective January 2026)

Components

• Housing: extruded aluminum or formed steel
• LED boards and driver: dimmable drivers with 0-10V, DALI, or integrated sensors
• Optics: lenses, louvers, and asymmetric reflectors
• Mounting: recessed frames, surface brackets, aircraft cable or rod pendants, wall brackets
• Joiners and end caps: alignment hardware for continuous runs

Detailing

• Coordinate run lengths with room dimensions, ceiling grids, and structure; avoid odd fractional pieces
• Locate power feeds and drivers for access
• Use flangeless recessed versions in drywall with plaster-in kits
• Check glare (UGR) for workspaces and direct views from long corridors
• Integrate sensors and emergency drivers in runs where required
• Align with millwork, columns, and ceiling changes for a clean result

Uses

Specific uses

• Open offices and classrooms
• Corridors and circulation
• Retail and showrooms
• Architectural lines in lobbies
• Wall washing and grazing

Pros and cons

Pros

• Efficient, even general lighting
• Strong architectural expression
• Continuous runs simplify layouts
• Many mounting and optical options

Cons

• Long runs need careful coordination and tolerances
• Custom lengths increase lead time and cost
• Glare from low-quality lenses
• Field cutting limited to certain products

Manufacturing and cost

Construction

• Housings extruded and cut; LED boards and drivers installed; lenses and end caps fitted
• Installed with mounting frames, cables, or brackets; joined and wired in place

Main manufacturers and suppliers

• Acuity Brands (Peerless, Mark Architectural Lighting)
• Signify
• Cooper Lighting Solutions
• Focal Point
• Prudential Lighting
• Visa Lighting

Trade associations: Illuminating Engineering Society and DesignLights Consortium.

Typical costs

• Commercial linear LED pendant fixture, material: $150 to $600 each; architectural custom runs priced per foot
• Commercial interior lighting installed (fixtures, labor, controls): roughly $3 to $15 per sq ft of floor area depending on scope

Sources

• CSE Magazine: specifying LED luminaires, https://www.csemag.com/specifying-led-luminaires/
• Leotek: LM-80 and TM-21 explained, https://leotek.com/lm-80-and-tm-21-for-streetlights-what-the-test-results-do-and-do-not-prove/
• PacLights: commercial building lighting fixtures guide, https://www.paclights.com/learning-center/commercial-building-lighting-fixtures-guide/
• DOE: LED standards overview, https://www1.eere.energy.gov/buildings/publications/pdfs/ssl/richman_standards_lightfair2014.pdf
• DesignLights Consortium: technical requirements, https://designlights.org/
• Wikimedia Commons: Dialedtube20251109.svg, by OnionBulb (CC BY-SA 4.0), https://commons.wikimedia.org/wiki/File:Dialedtube20251109.svg