Electrical Thumb Rules-Illumination-(Part-17).


Lighting levels

Chartered Institution of Building Services Engineers (CIBSE)

Building Lux
Areas common to most buildings
Entrance hall, lobby, waiting room 200
Enquiry desk 500
Corridor, passageway, stairs 100
Atria 50-200
Changing room, cloakroom, lavatory 100
Rest room 150
Canteen, cafeteria, dining room 200
Kitchen 300
Commercial offices  
General offices 500
Computer workstations 300-500
Conference rooms, executive offices 500
Computer and data preparation rooms 500
Filing room 300
Banks and building societies  
Counter, office area 500
Public area 300
Entrance halls 100
Reception, cashiers and porters’ desks 300
Bars, coffee bars, dining rooms, grill rooms, restaurants, lounges 50-200
Cloakrooms, baggage, rooms 100
Bedrooms 50-100
Bathrooms 150
Kitchen 150-300
Small retail outlets 500
Grocery/vegetable stores 500
Showrooms 1000
Covered arcades and malls 500-700
Fashion 500-750
Supermarket 750
Restaurant 200
Bookshop, chemist, jeweler 500
Superstore 1000
Electrical/furniture store 750
Arcades and malls 50-300
Places of public assembly
Cinema and theatre foyer 200
Booking office 300
Auditoria 100-150
Library 150-300
Museum art gallery 50-300
Lecture theatre 300
Church 100-300
School and College  
Computer Room 300
Classroom and Tuition Centre 350
Technical Drawing Room 750
Museum and Science Centre  
General Area and Corridor 150
Common Toilet and Restroom 200
Special Lighting for Paintings 300
Special Lighting for Sculptures 750
Retail Shop and Outlet  
Sales Area and Premises 400
Gift Wrap Station 450
Cash Register Counter 500
Commercial Space and Office  
Lift Lobby 200
Corridor 300
Toilet and Restroom 150
Cafeteria 350
Plant Room (AHU, Genset etc.) 150
Store Room 180
Lift Lobby 200
Corridor 250
Waiting Area and Lobby 300
Common Toilet and Restroom 250
Waiting rooms 200
Counseling Room 200
Breast-Feeding Room 200
Intensive Care Unit 300
High Dependency Unit 300
Isolation Room 300
Isolation Room – Ante Room 300
Delivery Suite – Labor Room 300
Simple examination room 300
Operating Theatre – Air-Lock 300
CSSD/TSSU – Sterilization Area 300
CSSD/TSSU – Packing Area 500
Patient Ward – Room 300
Patient Ward – Toilet 150
Operating theatre 1000
Conference Room 400
Catering Dept – Main Kitchen 400
Catering Dept – Beverage Kitchen 300
Catering Dept – Refuse Holding 150
Nursing Homes
Entrance lobbies 200
Lounges (communal) 300
Kitchens 300
Bathrooms 150
Toilets 100
Corridors 100
Staircases 100
Quiet / rest rooms 100
Dining rooms 200
Stores 100
Hotel and Restaurant  
Lift Lobby 150
Corridor 150
Common Toilet and Restroom 150
Bar 150
Bedroom 200
Conference Room 400
Exhibition Hall 500
Cinema, Concert Hall and Theatre  
Entrance Foyer 200
Auditorium 150
Toilet and Restroom 200
Dress Change 300
Make-Up Room 400
Residential Buildings  
Living Room 200
Dining Room 250
Kitchen 250
Bedroom 180
Bathroom 150


Lighting Levels

Chartered Institution of Building Services Engineers (CIBSE)

Area Illuminance (lux)
Lifts 100
Corridors and stairs 100
Toilets 100
Canteens 300
Mess rooms 150 – 300
Plant rooms 150 – 300
Store rooms 100


Recommended Lighting Levels

Singapore Standards SS 531-1 : 2006 (2013)

Type of area, task or activity Lux
Shipyards & Docks  
Shipyard area, storage areas 20
Short term handling of large units 20
Ship hull cleaning 50
Ship hull painting and welding 100
Mounting of electrical and mechanical components 200
Building Sites  
Clearance, excavation and loading 20
Construction areas, drain pipes mounting, auxiliary and storage tasks 50
Framework element mounting, light reinforcement work, wooden mould and framework mounting, electric piping and cabling 100
Element jointing, electrical machine and pipe mountings 200
Very Low Risk: Storage areas with occasional traffic in industrial outdoor 5
Low Risk: Occasionally used platforms and stairs in petrochemical industries 10
Medium Risk: Pre-Fabrication yards, Vehicle storage, Fuel storage 20
High Risk: Areas with pits / excavations, Valves, compressors area, regularly used staircase and platforms 50
Office Interior  
Filing, copying 300
Writing, reading, Data processing 500
Technical drawings 750
CAD work stations 500
Conf& Meeting rooms 500
Reception desk 300


Recommended Lighting Levels 


Area Lux
General Area
Entrance halls 100
Lounges 200
Circulation area and corridors 100
Stairs, escalators, travelators 150
Loading ramps/bays 150
Canteens 200
Rest rooms 100
Rooms for physical exercise 300
Cloakrooms, washrooms, bathrooms, toilets 200
Sick bay 500
Rooms for medical attention 500
Plant rooms, switch gear rooms 500
Dispatch packing handling areas 300
Control station 150
Agriculture building
Loading and operating of goods handling equipment and machinery 200
Building for livestock 50
Sick animal pens, calving stalls 200
Feed preparation, dairy, utensil washing 200
Preparation and baking 300
Finishing, glazing,decorating 500
Cement, concrete, & bricks industry
Drying 50
Preparation of materials,work on kilns and mixers 200
General machine work 300
Rough forms 300
Ceramics and glass industry
Drying 50
Preparation, general machine work 300
Enameling, rolling, pressing, shaping simple parts, glazing 300
Grinding, engraving, glass polishing, shaping precision parts, manufacture of glass instruments 750
Decorative work 500
Grinding of optical glass, crystal hand grinding and engraving, work on average goods 750
Precision work e.g decorative grinding, hand painting 1000
Manufacture of synthetic stones precious 1500
Chemicals, plastics and rubber industry
Remote operated processing installations 50
Processing installations with limited manual intervention 150
Constantly manned work places in processing installations 300
Precision measuring rooms, laboratories 500
Pharmaceutical production 500
Tire production 500
Color inspection 1000
Cutting, finishing, inspection 750
Electrical industry
Cable and wire manufacture 300
Wending -large coils 300
Wending-medium-sized coils 500
Wending-small Coils 750
Coil impregnating 300
Galvanizing 300
Assembly work-rough e.g. large transformers 300
Assembly work- medium e.g. switchboards 500
Assembly work- fine e.g. telephones 750
Assembly work-precision e.g. measuring equip. 1000
Assembly work-Electronic workshops, testing, adjusting 1500
Prayer Area, Mosques 300
Arrival and departure halls, baggage claim areas 200
Connecting areas, escalators, travelators 150
Information desks, check in desks 500
Customs and passport control desks 500
Waiting areas 200
Luggage store rooms 200
Security check areas 300
Air traffic control tower 500
Air traffic rooms 500
Testing and repair hangars 500
Engine test areas 500
Measuring areas in hangars 500
Platforms and passenger subways (underpasses) 50
Ticket hall and concourse 200
Ticket and luggage offices and counters 300
Waiting rooms 200
Health care premises
Waiting rooms 200
Corridors: during the day 200
Corridors: during the night 50
Day rooms 200
Staff office 500
Staff rooms 300
 Wards-General lighting 100
 Wards-Reading lighting 300
Wards-Simple examination 300
Examination and treatment 1000
Night lighting, observation lighting 5
Bathrooms and toilets for patients 200
Examination room general 500
Ear and eye examination 1000
Reading and Color vision test with vision charts 500
Scanners with image enhancers and television systems 50
Dialysis rooms 500
Dermatology rooms 500
Endoscopy rooms 300
Plaster rooms 500
Medical baths 300
Massage and radiotherapy 300
Pre-operation and recovery rooms 500
Operating theatre 1000
Intensive care- General lighting 100
Intensive care- Simple examinations 300
Intensive care-Examination and treatment 1000
Intensive care– Night watch 20
Dentists- General lighting 500
Dentists- At the patient 1000
Dentists- Operating cavity 5000
Dentists- White teeth matching 5000
Color inspection (laboratories) 1000
Sterilization rooms 300
Disinfection rooms 300
Autopsy rooms and mortuaries 500
Autopsy table and dissecting table 5000
Educational buildings
Play school room 300
Nursery class 300
Nursery craft room 300
Classrooms, tutorial rooms 300
Classroom for evening classes and adults education 500
Lecture hall 500
Black board 500
Demonstration table 500
Art and craft rooms 500
Art rooms in art schools 750
Technical drawing rooms 750
Practical rooms and laboratories 500
Teaching workshop 500
Music practice rooms 300
Computer practice rooms 500
Language laboratory 300
Preparation rooms and workshops 500
Student common rooms and assembly halls 200
Teachers rooms 300
Sports halls, gymnasiums and swimming pools 300
Public car parks (indoor)
In/out ramps 300
In/out ramps (at night)  75
Traffic lanes 75
Parking areas 75
Ticket office 300
Bookshelves 200
Reading area 500
Counters 500
Places of entertainment
Theatres & concert halls 200
Multipurpose halls 300
Practice rooms, dressing rooms 300
Museums (general) 300
Restaurants and hotels
Reception/cashier desk, porters desk 300
Kitchen 500
Restaurant, dining room, function room 200
Self-service restaurant 200
Buffet 300
Conference rooms 500
Corridors 100
Sales area small 300
Sales area large 500
Till area 500
Wrapper table 500


Illuminance values

As per IES

Area Type Lux
Corridors, Passageway 100
Lift 150
Stairs 150
Escalator 150
External Covered Ways 30
Entrance halls, lobbies, waiting rooms 150
Enquiry desk 500
Gate houses 300
Foods stores 150
General 500
Controlled entrance halls or  exit gate 150
Entrance and exit car park 30
Stores, stockyards 30
Industrial covered ways 50
Centre cafeterias, dining room 300
Consultant room, treatment areas 500
Medical stores 100
Rest room 150
Changing locker and cleaner’s room, cloakrooms lavatories 150
Rest rooms 150
Telecommunication board,switchboard rooms 500
Cordless switchboard 300
Apparatus rooms 150
Teteprinter rooms 500
Aircraft engine testing 750
Inspection and repairs (hanger) 500
External apron general 50
Pumps 300
Parking areas (interior) general repairs servicing 30
Greasing, pits washing, polishing 500
Exterior walkways and platforms 50
Exterior stairs and ladders 100
Retort house, oil gas plants, watergas plant purifier, indoor coke 100
Booster and exhauster houses 150
General 1000
Rough work e.g. counting rough Checking of stock parts 300
sub-assemblies 500
Fine work e.g. radio and telecommunication equipment, calibrated scales, precision mechanism, instruments 1000
Very fine work e.g. gauging and inspections of small intricate parts 1500
Minute work e.g. very small instruments 3000
Living rooms general 50
Casual reading 150
Sewing darningsrudies desk and protuged 300
Bedroom general 50
Bed lead kitchen 150
Bathrooms 100
Halls and landings 150
Stairs 100
Workshops 300
Garages 50
Athletics, basketball, bowls, judo 300
Hockey 700
General  Table special lighting 100
Top pool 500
Spectator areas 150
Club recreational 300
Changing rooms showers, lookers rooms 150
Club 300
Recreational 200
Ward unit bed heads general 30
General 150
Nurse station evening 300
Pharmacies dispensing bench 500
Shelves 150
Reception general 300
Enquiry desk 500
Laboratories 500
Operating theatre suits general 400
Operating area 30-50
X-ray department radio diagnostic and rooms fluoroscopy 500
Airport coach and railway station
Reception areas (desk),customs and immigration halls 500
Railway stations booking offices 500
Railway station parcel and left luggage offices counters 300
Circulation area 150
Waiting area 300
Assembly halls general 300
Teaching spaces general 300
Teaching spaces general 300
General where also used for further education 500
Chalkboard 500
Beedlework rooms 500
Laboratories 500
Workshop 300
Gymnasium 300
Music practice rooms 300
Exhibits insensitive to light 300
Light sensitive exhibits 150
Specially light sensitive exhibit 50
Shelves, book stack 150
Reading table 300
Reading rooms, newspaper and magazines 300
Reference libraries 500
Counters 500
Cataloging and sorting 500
Binding 500
Closed book store 100
Theatre and concert halls 100
Cinemas 50
Multipurpose 500
Conventional with counters 500
Conventional with wall display 500
Conventional with wall display 500
Self service 500
Supermarkets 500
Hypermarkets 500
General 500
Executive office 500
Computer rooms 500
Punch card rooms 750
Drawing offices drawing boards 750
Reference table and general 500
Print room 300
General office with mainly clerical task and typing office 500
Deep plan general offices 750
Business machine and typing 750
Filling room 300
Conference rooms 750
Aircraft Industry
Maintenance area 750
Inspection area 1000
Paint Shop 1000
Testing area 750
Instruments assembly 1500
Electrical assembly 1500
Explosives Manufacturing
Furnaces, Boiling Tanks, Driers 200
Mechanical furnaces, mechanical driers, generators 500
Paint Shop
Simple spraying 200
Fine finishing 500
Extra fine finishing 2000
Paint Manufacturing
Processing 200-500
Mix comparison 1000-2000
Electricity generating station
Boilers area 50
Cooling towers 50
Fuel handling 50
Storage tanks 10
Transformer yards 50
Turbine areas 50
Petroleum, Chemical and Petrochemical Industry
Process areas
General process units
Pump rows, valves, manifolds 50
Heat exchangers 30
Maintenance platforms 10
Operating platforms 50
Cooling towers (equipment areas) 50
Furnaces 30
Ladders and stairs (inactive) 10
Ladders and stairs (active) 50
Gauge glassed 50
Instruments (on process units) 50
Compressor house 200
Separators 50
General area 10
Control rooms and houses
Ordinary control house 300
Instrument panel 300
Console 300
Back of panel 100
Central control house 500
Instrument panel 500
Console 500
Back of panel 100
Specialty process units
Electrolytic cell room 50
Electric furnace 50
Conveyors 20
Conveyor transfer points Change house 50
Locker room, shower 100
Lavatory 100
Clock house and entrance gatehouse Card rack and clock area 100
Entrance gate, inspection 150
General 50
Eating 300
Serving area 300
Food preparation 300
General, halls, etc. 100
Garage and firehouse
Storage and minor repairs 100
First aid room 700
Iron and Steel Industry
Open hearth
Stock yard 100
Charging floor, Pouring side , Slag pits 200
Control platforms 300
Mold yard 50
Kilns (operating area) 50
Extruders and mixers 200
Non process areas
Loading, unloading, and cooling
water pump houses
Pump area 50
General control area 150
Control panel 200
Boiler and air compressor plants
Indoor equipments 200
Outdoor equipments 50
Tank fields (where lighting is required)
Ladders and stairs 5
Gauging area 10
Manifold area 5
Loading racks
General area 50
Tank car 100
Tank trucks, loading point 100
Electrical substations and switch yards
Outdoor switch yards 20
General substation outdoor 20
Substation operating aisles 150
General substation indoor 50
Switch racks 50
Plant road lighting (where lighting is Required)
Frequent use (trucking) 4
Infrequent use 2
Plant parking lots Aircraft obstruction lighting 1
Laboratories Qualitative, quantitative and physical test 500
Research, experimental 500
Pilot plant, process and specialty 300
ASTM equipment knock test 300
Glassware, washrooms 300
Fume hoods 300
Stock rooms 150
Warehouse and stock rooms
Indoor bulk storage 50
Outdoor bulk storage 5
Large bin storage 50
Small bin storage 100
Small parts storage 200
Counter tops 300
Repair shop
Large fabrication 200
Bench and machine work 500
Craneway, aisles 150
Small machine 300
Sheet metal 200
Electrical 200
Instrument 300
Hot top 300
Hot top storage 100
Checker cellar 100
Buggy and door repair 300
Stripping yard 200
Scrap stockyard 100
Mixer building 300
Calcining building 100
Skull cracker 100
Rolling mills
Blooming, scabbing, hot strip Hot sheet 300
Cold strip, plate 300
Pipe, rod, tube, wire drawing 500
Merchant and sheared plate 300
Tin plate mills Tinning and galvanizing 500
Cold strip rolling 500
Motor room, machine room Inspection 1000
Black plate, bloom and billet chipping Tin plate and other bright surfaces 2000


Electrical Thumb Rules-Illumination-(Part-16).

Illumination Requirements per Building & Fire Codes

Walking Surface or Area Lighting Level (Lux) Lighting Level (Lux)
NFPA 1 & 101 IFC/IBC / ICC 
New stairways 10.8 10.8
Floors & other walking surfaces (not stairs) 10.8 10.8
Assembly areas during performances 2.2 2.2


Illumination Level

Lux Level Work Activity and Function Example of User Area
20 – 80 Public walking Public parks and open-air car parks
100 – 140 Casual non-visual task Corridors, changing rooms, office restrooms
150 – 180 Some perception of detail Warehouses, stores, plant rooms, lift lobbies
200 – 240 Continuous occupation Entrance halls, dining rooms
250 – 300 Very easy visual task Public toilet, classrooms
300 – 400 Moderately easy visual task Private office, libraries, lecture theatres
500 – 600 Moderately difficult visual task Offices, laboratories, retail outlets
750 – 900 Difficult visual task Supermarkets, technical drawing offices
1000 – 1300 Very difficult visual task Operating theatres, polishing and painting plant
1500 – 1800 Extremely difficult visual task Assembly plants, inspection plants
> 2000 Exceptionally difficult visual task Precision assembly, fine work inspection


Illumination Level

Australian Standard AS/NZS 1680.2.2 under Table 3.1

Areas and Activities Examples Illumination (lux)
Interiors rarely visited where lighting is only required to aid movement and orientation Pass-though corridors and walkways; cable tunnels; indoor storage tanks 40
Areas of intermittent use for tasks of coarse detail Movement, orientation and tasks of coarse detail in areas such as change rooms, storage rooms, loading bays etc. 80
Areas that are continually used for tasks of coarse detail Simple tasks such as occasional reading of clearly printed documents for short periods or rough bench or machine work in areas such as waiting rooms and entrance halls etc. 160
Continuously occupied interiors used for ordinary tasks with high contrasts or large detail Food preparation areas; counters for transactions; school boards; medium woodworking 240
Areas where visual tasks are moderately difficult and include moderate detail with low contrast Routine office tasks such as reading, typing and writing in office spaces or enquiry desks 320
Medium level inspection work such as fine woodwork or car assembly 400
Areas where visual tasks are difficult with small detail with lower contrast Visually difficult tasks including most inspection tasks such as proofreading, fine machine work or fine painting 600
Areas where visual work are very difficult and involve very small detail with very low contrast Very difficult tasks such as fine inspection, paint retouching or fine manufacture 800
Areas where visual work is extremely difficult with extremely small detail with very low contrast Extremely difficult tasks that may require visual aids such as graphic arts inspection; hand tailoring; inspection of dark goods; extra-fine bench work etc. 1200
Areas where visual work is exceptionally difficult with exceptionally small detail with very low contrast Exceptionally difficult tasks where visual aids would be of advantage such as the assembly of minute mechanisms and jewellery and watch making 1600


Illumination Level

Illuminance Example
Full moon overhead 1 lux
Family living room 50 lux
Hallway/toilet 80 lux
Very dark overcast day 100 lux
Sunrise or sunset on a clear day. Well lit office area 400 lux
Overcast day, typical TV studio lighting
Full daylight (not direct sun) 10000-25000 lux
Direct sunlight 32000-130,000 lux


Illumination Level

IS 3646 (PART-1) 1992

Types of interior or activity illuminance (lux)
Entrance Halls, Lobbies, Waiting Rooms 150-200-300
Inquiry desks  300-500-750
Gatehouses  150-200-300
 Circulation Areas
Lifts 50-100-150
Corridors, Passageway, stairs 50-100-150
 Escalator, travellators 100-150-200
Medical and First aid Centers
Consulting Rooms, Treatment Rooms 300-500-750
Rest Rooms 100-150-200
Medical stores 100-150-200
 Staff Rooms
 Changing, locker and cleaner Rooms, Cloakrooms, lavatories 50-100-150
 Rest Rooms 100-150-200
 Staff Restaurant
Canteens, cafeterias, dining rooms Mess rooms 150-200-300
Servery, vegetable preparation, washing-up area 200-300-500
Food preparation and cooking 300-500-750
 Food stores, cellars 100-150-200
Switchboard rooms 200-300-500
Telephone apparatus room 100-150-200
Telex room, post room  300-500-750
Reprographic room  200-300-500
Building Services
 Boiler houses General 50-100-150
Boiler front 100-150-200
 Boiler control room 200-300-500
Control rooms 200-300-500
Mechanical plant room 100-150-200
Electrical power supply and distribution Room 100-150-200
Store rooms 50-100-150
Car Parks
 Floors 5 to 20
 Ramps and Corners 30
Entrances and Exits 50-100-150
Control Booths 150-200-300
 Outdoor Car Parks 5-20 5 to 20
Ticket counters, checking, desks And Information desks 300-500-750
Departure lounges, other waiting Areas 150-200-300
 Baggage reclaim 150-200-300
 Baggage handling 50-100-150
 Customers and immigration halls  300-500-750
Concourse 150-200-300
Railway Stations
Ticket office 300-500-750
Information Office 300-500-750
Parcels office, left Luggage Office General 50-100-150
Counter  150-200-300
Waiting rooms 150-200-300
Concourse 150-200-300
Time table 150-200-300
Ticket Barriers  150-200-300
Platforms (covered) 30-50-100
Platforms (open) 20
 Ticket offices 300-500-750
Information offices  300-500-750
Concourse  150-200-300
Loading Areas 100-150-200
 Assembly Halls
General  200-300-500 3
Teaching Spaces
General  200-300-500
 Lecture Theatres
 General 200-300-500
Demonstration benches  300-500-750
Seminar Rooms  300-500-750
 Art Rooms 300-500-750
 Needlework Rooms  300-500-750
 Laboratories  300-500-750
Libraries 200-300-500
Music rooms  200-300-500
 Sport halls  200-300-500
 Workshops 200-300-500
Public rooms, Village Halls, Worship Halls 200-300-500
 Concert Halls, Cinemas and theatres
 Foyer 150-200-300
Booking Office 200-300-500
Auditorium 50-100-150
Dressing Rooms 200-300-500 
Projection Rooms 100-150-200
 Body of church 100-150-200
Pulpit, Lectern 200-300-500
 Choir Stalls 200-300-500
Alter, communion table, cancel 100-150-200
Vestries  100-150-200
 Organ 200-300-500
Anesthetic Rooms-General 200-300-500
Anesthetic Rooms-Local 750-1000-1500
 Consulting Area- General 200-300-500
 Consulting Area-Examination 750-1000-1500
Corridors-General 100-150-200
Ward corridors-Day, screened from bays  150-200-300
Ward corridors- Day, open to natural light 150-200-300
Ward corridors- Morning/evening 100-150-200
Ward corridors- Night 5 to 10
Cubicles- General  200-300-500
Cubicles-Treatment 750-1000-1500
Examination- General 200-300-500
Examination- Local inspection  750-1000-1500
 Intensive therapy-Bad head 30-50
 Intensive therapy- Circulation between bed ends 50-100-150
 Intensive therapy- Observation 200-300-500
 Intensive therapy- Local observation 750-1000-1500
 Intensive therapy- Staff base(day) 200-300-500
 Intensive therapy- Staff base(night) 30
 Laboratories-General 200-300-500
 Laboratories-Examination 300-500-750
Nurses stations- Morning/day/evening 200-300-500
Nurses stations- Night desks 30
Nurses stations-Night, medical trolleys 50-100-150
Operating theatres- General 300-500-750
Operating theatres-Local  10000 to 50000
Pathology department- General 200-300-500
Pathology department-Examination 300-500-750
Pathology department- Pharmacies 200-300-500
Pathology department-Reception/ inquiry 200-300-500
Pathology department-Recovery rooms 200-300-500
 Ward circulation-Day 50-100-150
 Ward circulation-Morning/evening 50-100-150
 Ward circulation-Night 3 to 5
Ward bed head-Morning/Evening 30-50
Ward bed head- Reading  100-150-200
Night- Adult 0.1-1
Night-Pediatric 1 to 5
Night-Psychiatric 5
X-ray Areas-General 150-200-300
X-ray Areas-Diagnostic 150-200-300
X-ray Areas-Operative 200-300-500
X-ray Areas- Process dark room 50
Surgeries-General 200-300-500
Surgeries-Waiting rooms  100-150-200
Dental Surgeries- Chair Special lighting Special lighting
Dental Surgeries-Laboratories 300-500-750
Consulting rooms- General 200-300-500
Consulting rooms- Desk 300-500-750
Consulting rooms-Examination 300-500-750
Consulting rooms-Ophthalmic wall & nearvision 300-500-750
Entrance Halls 50-100-150
 Reception, cashiers and porters Desks 200-300-500
 Bars, coffee base, dinning rooms, grill, rooms, restaurants, lounges 50-200
Cloak room 50-100-150 3
Bed room 30-50-100
 Bathroom 50-100-150
General 200-300-500 1
Counters 300-500-750
 Bookshelves 100-150-200
 Reading rooms 200-300-500
 Reading tables  200-300-500
Catalogues- Card 100-150-200
Catalogues- Microfiche/visual display units 100-150-200
Reference libraries- General 200-300-500
Reference libraries-Counters 300-500-750
Reference libraries- Bookshelves  100-150-200
Reference libraries- Study tables, carrels 300-500-750
Reference libraries- Map room 200-300-500
Display and exhibition- Exhibits insensitive to light 200-300-500
Library workrooms- Book repair and binding 300-500-750
Library workrooms- Catalogue and sorting 300-500-750
Library workrooms- Remote book stores 100-150-200
Museums and Art Galleries- Exhibits insensitive to light 200-300-500
Museums and Art Galleries- Light sensitive exhibits, for e.g., oil and temper paints, undyed leather, bone, Ivory, wood, etc 150
Museums and Art Galleries-  Extremely light sensitive exhibits ,For e.g., textiles, water colors, prints and drawing, skins, botanical specimens, etc 50
Museums and Art Galleries-  Conservation studies and workshops 300-500-750
Museums and Art Galleries- Multi-purpose sports hall 300-750
Inspection of farm products where Color is important 300-500-750
Other important tasks 200-300-500
 Farm workshops
 General 50-100-150
Workbench or machine 200-300-500
 Milk premises 50-100-150
Sick Animal Pets, Calf Nurseries  30-50-100
Other Firm and Horticulture Building 20-30-50
General plant
 Turbine houses (operating floor) 150-200-300
Boiler and turbine house basements 50-100-150
Boiler house, platforms, areas around Burners 50-100-150
Switch rooms, meter rooms, oil plant Rooms, HV substations (indoor) 100-150-200
 Control room  200-300-500
 Relay and telecommunication rooms 200-300-500
Diesel generator & compressor rooms 100-150-200
Pump houses, water treatment plant Houses 100-150-200
 Battery rooms, charges, rectifiers  50-100-150
Precipitator chambers, platforms, etc  50-100-150
Cable tunnels & basements, Circulating Water culverts & screen chamber 30-50-100
 Coal Plant-Conveyors, gantries, junction towers, Unloading hoppers, ash handling plants, Setting pits, dust hoppers 50-100-150
 Coal Plant-Other areas where operators may be Attendance 100-150-200
Nuclear Plants-Gas circulation bays, reactor area, boiler Platform, reactor charges and discharge 100-150-200
Structural steel Fabrication-General 200-300-500
 Structural steel Fabrication-Marking off 300-500-750
 Sheet Metal Works- Pressing, punching, shearing, stamping, spinning, folding 300-500-750
Bench work, scribing, inspection 500-750-1000
 Machine and tool shops-Rough bench and machine work 200-300-500
 Machine and tool shops- Medium bench and machine work 300-500-750
 Machine and tool shops-Fine bench and machine work  500-750-1000
 Machine and tool shops- Gauge rooms 750-1000-1500
 Die Sinking Shops-General  300-500-750
 Die Sinking Shops-Fine Works  1000-1500-2000
 Welding and soldering shops-Gas and arc welding, rough spot welding 200-300-500
 Welding and soldering shops-Medium soldering, brazing, spot welding  300-500-750
 Welding and soldering shops- Fine soldering , fine spot welding 750-1000-1500
Assembly Shops- Rough work for example, frame and heavy machine assembly 200-300-500
Medium work, for example , office Machinery assembly 300-500-750
 Fine work, for example, office machinery assembly 500-750-1000
Very fine work, for example, instrument assembly 750-1000-1500
 Minute work for example, watch making 1000-1500-2000
Inspection and Testing Shops
Coarse Work, for example, using go/on go gauge, inspection of large sub-assembly 300-500-750
Medium work for example, inspection of painted surfaces 500-750-1000
Fine work, for example, using calibrated scales, inspection of precision mechanism 750-1000-1500
 Very fine work, for example, inspection of small intricate parts 1000-1500-2000
 Minute work, for example, inspection of very small instruments 2000
Points Shops and Spray Booths- Dipping, rough spraying 00 200-300-5
Points Shops and Spray Booths-Preparation, ordinary painting, spraying & finishing 200-500-750
 Fine painting,. Spraying and finishing  500-750-1000
Inspection, retouching and matching 750-1000-1500
 Plating shops-Vats and baths 200-300-500
 Plating shops- Buffing, polishing burnishing 300-500-750
 Plating shops- Final buffing and polishing 500-750-1000
Electrical Equipment manufacture
 Manufacture of cables & insulated wires, winding, varnishing & immersion of coils, assembly of large machines, simple assembly work 200-300-500
 Medium assembly , for example Telephones, small motors 300-500-750
 Assembly of precision components for e.g., telecommunication equipment ,adjustment, inspection and calibration 750-1000-1500
Assembly of high precision parts 1000-1500-2000
Electronic Equipment Manufacture
Printed Circuit Board
 Silk Screening 300-500-75
 Hand insertion of components, soldering 500-750-1000
 Inspection  750-1000-1500
Assembly of wiring harness, clearing Harness , testing and calibration 500-750-1000
Chassis assembly 750-1000-1500
 Inspection and testing
 Soak test 150-200-300
Safety and functional tests  200-300-500
 Slaughter houses
 General 200-300-500
 Inspection 300-500-750
Canning, Preserving and Freezing 500-750-1000
Grading and sorting of raw materials  Preparation  300-500-750
 Canned and bottled goods Retorts  200-300-500
Automatic processes 150-200-300
 Labeling and packaging 200-300-500 3
 Frozen labeling
 Process area 200-300-500
Packaging and storage 200-300-500
 Bottling, Brewing & Distilling
Keg washing and handling, bottle  Washing 150-200-300
Keg inspection 200-300-500
Process area 200-300-500
 Bottle filling 500-750-1000
Edible oils and Fats Processing
Refining and Blending 200-300-500
Production  300-500-750
Mills-milling, Filtering and Packing 200-300-500
 General 200-300-500
Hand decorating, icing 300-500-75
Chocolate and Confectionery Manufacturer
 General  200-300-500
Automatic processes 150-200-300
 Hand decoration, inspection, wrapping and packing 300-500-750
Tobacco Processing
Material preparation, making and packing 300-500-750
 Hand processes 500-750-1000
Leather Manufacture-Cleaning, tanning and stretching, vats, cutting, fleshing, stuffing 200-300-500
 Finishing, scarfing 300-500-750
 Leather Work General  200-300-500
 Pressing, glazing  300-500-750
 Cutting, splitting, scarfing, sewing 500-750-1000
Clothing Manufacture
Preparation of cloth 200-300-500
 Cutting 500-750-1000
 Matching  500-750-1000
 Sewing  750-1000-1500
 Pressing 300-500-750
 Inspection  1000-1500-2000
 Hand tailoring  1000-1500-2000
Hosiery and Knitwear Manufacture
Flat bed knitting machines 300-500-750
Circular knitting machines  500-750-1000
 Lock stitch and over locking machine 750-1000-1500
Linking or running on 750-1000-1500
 Mending, hand finishing 1000-1500-3000
 Inspection 1000-1500-2000
Glove Manufacture
Sorting & grading 500-750-1000
Pressing, knitting, cutting  300-500-750
Sewing 500-750-1000
Inspection 1000-1500-2000
 Hat Manufacture
Stiffening, braiding, refining, forming, Sizing, pounding, ironing 200-300-500
 Cleaning, flanging, finishing 300-500-750
 Sewing 500-750-1000
 Inspection 1000-1500-2000 –
Boot and Shoe Manufacture Leather and Synthetics
 Sorting and Grading 750-1000-1500
Clicking, closing  750-1000-1500
Preparatory Operations 750-1000-1500
Cutting tables and pressure 1000-1500-2000
Bottom stock preparation, lasting, Bottoming finishing, show rooms 750-1000-1500
Washing, compounding, coating, drying Varnishing, vulcanizing 200-300-500
Lining, making and finishing 300-500-750
 Work stores  100-150-200
 Unpacking, sorting 150-200-300
 Large item storage  50-100-150
 Small item rack storage 200-300-500
Issue counter, records, storemans desk 300-500-750
Warehouses and bulk stores
Storage of goods where identification requires only limited preparation of details 50-100-150
 Storage of goods where identification 100-150-200
 Automatic high bay rack stores  Gangway 20
Control station 150-200-300
 Packing and dispatch  200-300-500
 Loading bays 100-150-200
 Cold stores
 General 200-300-500
Breakdown, make-up and dispatch 200-300-500
 Loading bays 100-150-200
General Offices  300-500-750
Deep plan General offices 500-750-1000
Offices Computer Work station  300-500-750
Offices- Conference Rooms, Executive Offices 300-500-750
 Computer and data preparation Rooms 300-500-750
Filling rooms 200-300-500
Drawing Offices-General  300-500-750
Drawing Offices- Drawing Board  500-750-1000
Print rooms 200-300-500
 Counter, office area  300-500-750
Banks and building societies- Public area  200-300-500
SERVICES Workshop  Garages
(Garages)Interior parking areas 20-30-50
(Garages) General repairs, servicing, washing, polishing 200-300-500
(Garages) Workbench 300-500-750
(Garages) Spray Booths  300-500-750
 External apron-General  30-50-100
Pump area (retail details )  200-300-500
 Workshop- General 200-300-500
 Workshop- Workbench 300-500-750
 Workshop-Counter 200-300-500
 Workshop- Stores 200-300-500
Commercial laundries- Receiving, sorting, washing, drying, Ironing, dispatch, dry-cleaning, bulk Machine work 200-300-500
Commercial laundries-Head ironing, pressing, mending, spotting, inspection 300-500-750
Commercial laundries-Launderettes 200-300-500
Commercial laundries-Walkways 30-50-100
Commercial laundries-Process areas 50-100-150
Small Shops with Counters 300-500-750
Small Self Service shops with island displays 300-500-750
 (Supper-Markets) , Hyper-Markets)General  300-500-750
(Supper-Markets) , Hyper-Markets)Checkout 300-500-750
(Supper-Markets) , Hyper-Markets)Showroom for large objects, for e.g. Cars, furniture 300-500-75
(Supper-Markets) , Hyper-Markets)Shopping precincts and arcades 100-150-200

Selection of Various Types of Inverter-(Part-3)

How to select Right Inverter

  • Before buying an inverter for, It is very important to understand what is the right inverter for our requirement for that we do understand the basics criteria of Inverter.
  • In order to make a good estimate of your power needs, you’ll need to take a look at all of the devices you plan on plugging into your new inverter.
  • If we only need to use one device at a time, then that’s the only one you’ll need to look at. However, you’ll need to add together the numbers from multiple devices (like an LCD screen and a video game system) if you plan on using them at the same time.

(A) Power Requirement:

  • One of the most important factors that we must know before buying an inverter is Power requirement.
  • Power requirement means all electrical appliances (like fan, tube lights, television,Pumps, CFL etc.), we want to run at the time of power failure. The power requirement is simply addition of the power consumed by various electrical equipments.
  • The thing we must understand that Inverter is not a Generator. Inverter has its own limitations. If power requirement is more than our estimation, then an inverter alone cannot create demands effectively.
  • High power inverter can run our refrigerator and air conditioners, but battery will not last more than few hours. Hence it better to estimate Inverter Load Carefully
  • The selection of correct size Inverter is very important, If we need to power small appliances like energy efficient light bulbs, we do not need to buy a 2000W power inverter because it will consume more power even in standby mode and work very inefficiently with small appliances. On the other hand, if we connect a coffee machine to a 150W inverter we will quickly blow a fuse, Therefore power estimation is important thing.
  • The size of Inverter depends on the watts (or amps) of what we want to run. It is recommend that we choose at least 10% to 20% more than our requirement.
  • Suppose you want 1No Fans, 1No Tube lights, 1No CFL and 1No television to operate at the time of power failure. Therefore the total power requirement to be (1×90 + 1×50 + 1×25 + 1×120) = 285 watts. Here Total Load is 285 watts.

(B) Surge Power (Starting Power):

  • Starting and running power requirement of all electric appliances are different.
  • Starting power of Electrical Equipment is several times greater than their normal working power.
  • An 18 Watts CFL takes around 25 Watts power to start and after few seconds it works on 18 Watts. Some appliances like Refrigerator, Washing Machine etc take almost double power to start as compared to the normal running power.
  • For example Gridding Machine have normal working power 1000W, their starting power is higher than 4000W, so inverters with continuous power 2000W are not suitable because their peak power is limited by 4000W.
  • For selecting right Inverter, Always take into account starting power requirements of your equipment, especially devices with electric motors, Electronics Choke, Capacity, inductive
  • The Size of the inverter should be chosen based on the power consumption of your load.
  • Resistive loads: All resistive loads like toaster, coffee maker, electric range, iron, Incandescent lamps, flood lighting. Laser Printers use Nichrome resistance wire in their heating
  • The Starting Power or Surge Power rating should be 6 times the Watt rating
  • Inductive Loads: All Inductive Load like induction motor, reciprocating pumps and compressors, refrigeration, air-conditioning, Oxygen Concentrators have more starting current.
  • The Starting current (LRA) should be 5 times the full load current (FLA).
  • Capacitive Loads: Switched Mode Power Supplies (SMPS), electronic equipment like battery chargers, computers, audio and video devices, radio etc.
  • The Starting Power or Surge Power rating should be  3  times the Watt rating
  • Microwaves :
  • The Initial power consummation by the microwave will be 2 times the cooking power.
  • A Water Supply Pump:
  • The starting surge can be 3 times the normal running rating of the pump
  • The inverter should, therefore, be sized adequately to withstand the high inrush current. 

 Starting Factor

Type of Device Starting Factor
Air conditioner 5
Refrigerator / Freezer 5
Air Compressor 4
Sump Pump / Well Pump / Submersible Pump 3
Dishwasher 3
Clothes Washer 3
Microwave 2
Furnace Fan 3
Industrial Motor 3
Portable Kerosene / Diesel Fuel Heater 3
Circular Saw 3
Bench Grinder 3
Incandescent / Halogen / Quartz Lamps 3
Laser Printer / Other Devices using Quartz Lamps for heating 4
Switched Mode Power Supplies 3
Photographic Strobe / Flash Lights 4

  (C) Rating (VA rating) of the inverter:

  • It stands for the Volt ampere rating. It is the voltage and current supplied by the inverter to the equipments.
  • If an inverter operates with 100% efficiency, then the power requirement of the electrical items and power supplied by inverter is same. But 100% or ideal conditions does not exist in real.  Most inverters have the efficiency range from 60 % to 80%. This efficiency is also called power factor of an inverter and is simply  the ratio of power required by the appliances to power supplied by an inverter. Power factor of most inverters ranges from 0.6 to 0.8.
  • Rating of inverter (VA) =Power consumed by equipments (watts) / Power factor (efficiency).
  • Power of inverter (VA) = 535/0.7 = 765 VA
  • In the market 800 VA inverters are available. So Size of an inverter with 800 VA.

 (D) Type of Battery

  • The performance and Life of an inverter depends on the battery Quality.
  • Battery stores the energy needed to run appliances during power cut.
  • There are three Type of Battery
  • Lead Acid Battery
  • Tubular Battery
  • Maintenance Free Battery
  • Normally high power Lead Acid batteries are used to power inverters.

 (E) Battery Capacity (Ah):

  • Capacity of a battery is expressed in terms of Ampere Hour (Ah). It is decide the back up hours of Inverter.
  • It indicates the rate of current a battery can supply for a given duration. If the capacity of a battery is 100 Ah, that battery can supply 100 Ampere current for 1 Hour or 1 Ampere Current for 100 Hrs
  • Battery capacity = Power requirement (watts) x Back up hours (hrs) / Battery Voltage (volts) x Battery Efficiency x No of Battery
  • Example: If Inverter Load is 390 Watt, We need 3 hours back up and Battery Voltage is 12V, Battery Efficiency is 90%
  • Battery Capacity = (390 x3) / 12×0.9×1 = 109 Ah
  • Therefore a battery capacity of 120 Ah.
  • In reality battery performance degrades with usage, so you are recommended to buy 5-10% higher capacity battery.
  • Therefore a battery with a capacity of 150 Ah is suitable for our requirement.
  • If we use series – parallel battery combination for backup is
  • Backup capacity(hours) = N series X Volts X Battery Ah X N parallel / (UPS capacity in VA)
  • Where, N series = no. of batteries in series and N parallel = no. of parallel battery banks

 (F) Backup Time (Hr):

  • Backup (hours) = Battery Ah X Battery Voltage X Inverter Efficiency / Total Load (Watt)

(G) Battery Voltage (12V, 24V or 48V):

  • We can choose Battery Voltage of 12V, 24Vor 48V for inverter. The selection is very important for Voltage drop and Cable size of Inverter.
  • To control load current within limit, as load increase, we should select higher size of Battery Voltage.
  • Let’s take example.
Watt Volt Amp Cable Resistance(Ω) Voltage Drop (V)
1000 12 83 0.01 0.8
2000 24 83 0.01 0.8
4000 48 83 0.01 0.8
  • As per above table, as the load increase, by selecting higher voltage,load current within limit.
  • Let’s take example of selecting different voltage for same load (Watt)
Watt Volt Amp Cable Resistance(Ω) Voltage Drop (V)
4200 12 350 0.01 3.50
4200 24 175 0.01 1.75
4200 48 87.5 0.01 0.88
  • At Higher Load (Watt), by selecting lower voltage (12V).The load current is high. The higher the current needs the bigger the components. High currents require large diameter cables and fuses, which are expensive and the entire system is not safe.
  • By only doubling the voltage we can get double the power (Watt) at the same current.
  • 12 Volt used to be a standard for extra low voltage power systems. Today, mostly systems are 24V or 48V and include a 230V AC inverter. This means the wiring of the house does not have to be different from any other grid-connected household and cabling cost is greatly reduced.
  • The Battery Cost for higher Voltage is not more for same rating of Battery. For 12KW Load, Instead of buying a battery which has a capacity of 1000AH at 12V, (12KWH) we can rearrange the battery as a 24V 500AH (12KWH) or 48V 250AH (12KWH). The total power available from the battery is exactly the same, but with lower losses in the cabling and inverter.
  • A higher volt inverter will be more expensive than a lower volt one, and for small setups, that extra expense is unnecessary.  If we are going to have high load demands, it makes more sense to go with a higher-volt inverter for a variety of reasons. 

(H) Battery Charger:

  • The battery capacity is limited to the size of the charger. Usually, the battery capacity should be no more than 12x the maximum charge current i.e. a 5A charger can only accommodate 60AH of batteries (5 x 12 =60).
  • If discharges are expected to be less frequent than once in every 10 days, We may use formula of 20x the maximum charge current.

(I) Discharge Rate:

  • Lead acid batteries have few Amps hour if the discharge rate is fast.
  • Generally, the lead acid battery discharge rate is slow. It is 20 hours.
  • At high discharge rate, the capacity of the battery drops steeply. Suppose the battery is 10 Ah and its discharge rate is 1C. One hour discharge of the battery at the rate of 1C (10 Amps in 1 hour), the capacity reduces to 5 Ah in one hour.
  • Suppose we want to run a load at 20 Amps for 1hour. Then the capacity of the battery is 20A x 1 Hour = 20Ah.
  • Keep discharge rate to maximum 80%. Then the battery capacity should be 20Ah / 0.8 = 25 Ah
  • So a 25 Ah battery can give 20 Amps current for 1 hour to run the load.
  • But it is better to drain the battery to 50% only then, 25 Ah / 0.5 = 50 Ah.
  • Hence it is better to use a 50Ah battery to run the load at 20 Amps per Hour to keep 50% charge in the battery.
Battery Capacity Hours of Discharge
100 20
90 10
87 8
83 6
80 5
70 3
60 2
50 1



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