What is the recommended lux level for an office?

300-500 lux for general office work per IS 3646. 500 lux for detailed paperwork. For computer work, 300 lux is sufficient with attention to screen glare.

How do I calculate the number of lights needed?

Use the lumen method: N = (E × A) / (n × F × UF × MF). Where E=required lux, A=room area(m²), n=lamps per fixture, F=lumens/lamp, UF=utilization factor(0.4-0.6), MF=maintenance factor(0.6-0.8).

IS 3646:2009 — Code of Practice for Interior Illumination

IS 3646 : 2009

Code of Practice for Interior Illumination

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Summary

IS 3646 is the primary Indian standard for interior lighting design. It specifies recommended illumination levels (in lux) for every type of space — offices (300-500 lux), classrooms (300 lux), hospital OT (10000 lux), corridors (100 lux), etc. Essential reference for electrical and architectural design.

Code of practice for interior illumination of buildings covering recommended illumination levels, glare control, colour rendering, and lighting design for various activities and spaces.

Key Values

Office (general)300-500 lux

Classroom300 lux

Drawing office750 lux

Practical Notes

! These are MAINTAINED illuminance levels — new installation should provide 20-30% more to account for lamp depreciation and dirt.

! Maintenance factor (MF) for clean office = 0.8. For dusty industrial = 0.6. Always apply MF in calculations.

! LED fixtures have changed economics — higher lux levels are now affordable. Consider exceeding IS 3646 minimums.

! Glare control is as important as lux level — specify luminaire with appropriate glare class for the task.

Cross-Referenced Codes

IS 3646:2009Code of Practice for Interior Illumination

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