TK 4161 CM 1919 General Lighting Safety Orders UC-NRLF Issued by the Industrial Accident Commission of the State of California 525 MARKET STREET, SAN FRANCISCO Effective December 1, 1919 CALIFORNIA STATE PRINTING OJTIC1 SACRAMENTO 1919 General Lighting Safety Orders Issued by the Industrial Accident Commission of the State of California 525 MARKET STREET, SAN FRANCISCO Effective December 1, 1919 CALIFORNIA STATE PRINTING OFFICE SACRAMENTO 1919 (7800 INDUSTRIAL ACCIDENT COMMISSION OF THE STATE OF CALIFORNIA 525 Market Street, San Francisco 423 Union League Building, Los Angeles , Chairman. A. H. NAFTZGER, Commissioners. H. M. WOLFLIN, Superintendent of Safety. SUMMARY OF THE SAFETY PROVISIONS of the Workmen's Compensation, Insurance and Safety Act. Being Chapter 176 of the Laws of 1913 as Amended by Chapter 607 of the Laws of 1915, and Chapter 586 of the Laws of 1917. Sections 33 to 54, inclusive, of the Workmen's Compensation, Insur- ance and Safety Act give the Industrial Accident Commission power to make and enforce safety orders, rules and regulations, to prescribe safety devices, and to fix safety standards. It also empowers the Commission to appoint advisers who shall, without compensation, assist the Com- mission in establishing standards of safety. The Commission may adopt and incorporate in its general orders such safety recommendations as it may receive from such advisers. The Commission, carrying out its plan of obtaining the best practical ideas to incorporate in its Safety Orders, asked various interests to serve on a committee to draft Tentative General Lighting Safety Orders. COMMITTEE ON GENERAL LIGHTING SAFETY OEDEBS. ROMAINE W. MYERS (chairman), consulting engineer (electrical and illuminating), representing the National Council of Defense, Divis- ional Committee on Lighting. L. E. VOTER (vice chairman), illuminating engineer, General Electric Company, representing the Association of Electrical Manufacturers and the Lighting Fixture Association. W. W. HANSCOM, electrical and mechanical engineer, representing the National Electric Light Association, Pacific Coast Section. SMITH O'BRIEN, architect, representing the American Institute of Architects. R. H. FENKHAUSEN, electrical engineer, Bethlehem Shipbuilding Corpo- ration, Union Plant, representing the American Institute of Electrical Engineers. DANIEL C. MURPHY, president California State Federation of Labor. PAUL SCHARREXBERG, secretary-treasurer California State Federation of Labor. R. S. PRUSSIA, illuminating engineer, Westinghouse Lamp Company, representing the Association of Electrical Manufacturers. MILES F. STEEL, Benjamin Electric Manufacturing Company, repre- senting the Association of Electrical Manufacturers. S. J. LISBERGER, Engineer, San Francisco District, Pacific Gas and Electric Company, representing the Pacific Coast Gas Association. CHAS. M. MASSON, illuminating engineer, Southern California Edison Company, representing the Illuminating Engineering Society. CONSTANT MEESE, Meese & Gottfried Company, representing the San Francisco Chamber of Commerce. F. DOHRMANN, JR., Nathan-Dohrmann Company, representing the San Francisco Chamber of Commerce. HARRY GORMAN, field agent, representing the Bureau of Labor Statistics. H. B. WOODILL, president Woodill & Hulse Electric C9mpany, Inc., representing the Merchants and Manufacturers Association of Los Angeles. W. A. CHOWEN, manager California Inspection Rating Bureau, repre- senting the Casualty Underwriters Board of California. D. AYRE, superintendent inspection department, California Inspection Rating Bureau, representing the Casualty Underwriters Board of California. HAROLD MESTRE, representing the Industrial Welfare Commission. ROBT. L. ELTRINGHAM, electrical engineer, representing the Indus- trial Accident Commission. JOHN R. BROWNELL (secretary), superintendent of safety, Industrial Accident Commission. Acknowledgment is made of the assistance rendered by the Illuminating Engineering Society in the preparation of these General Lighting Safety Orders, and for the use of the various cuts which they kindly loaned. M48977 GENERAL LIGHTING SAFETY ORDERS. Order 1500. Definitions. (a) Candle (or candlepower) means the unit of luminous intensity maintained by the national laboratories of the United States, France and Great Britain. (b) Lumen means the unit of luminous flux, and is the quantity of light necessary to produce an average intensity of illumination of one foot-candle over an area of one square foot. (c) Foot-candle means the unit of illumination equal to one lumen per square foot. It is the lighting effect produced upon an object by a lamp of one candlepower at a distance of one foot. (d) Photometer means a standardized instrument suitable for making illumination measurements. (e) Lamp means that part of the lighting equipment from which the light originates. (/) Local lamps (or lighting) means lighting units located close to the work, and intended to illuminate only a limited area about the work. (g) Overhead lamps (or lighting) means lighting units installed above ordinary head-level to secure a general illumi- nation over a considerable area. (h) Brightness means the intensity of light per unit area emitted from, or reflected by, a body ; and in these Orders is expressed in candlepower per square inch. (i) Glare means any brightness within the field of vision of such a character as to cause discomfort, annoyance, interfer- ence with vision, or eye fatigue. (j) Eyestrain means a physiological condition of the eye resulting in discomfort, poor vision, or fatigue. (k) Shaded means that the lamp is equipped with a reflector, shade, enclosing globe, or other accessory for reducing the brightness in certain directions, or otherwise altering or chang- ing the distribution of light from the lamp. (I) Illumination means the quantity of light received upon a surface ; it is measured in foot-candles or in lumens per square foot of area. (m) Intensity of illumination means the quantity of light received upon a surface, expressed in foot-candles or in lumens per square foot of area. GENERAL LIGHTING SAFETY ORDERS. 5 (n) Foot-candles at the work means the intensity of illumi- nation on the object upon which work is being performed. (0) Foot-candles at floor-level means the intensity of illumi- nation on the floor of the space specified. Order 1501. General Requirements. (a) Working or traversed spaces in buildings or grounds of places of employment shall be supplied during the time of use, with either natural or artificial light in accordance with the following Orders (1502-1509). Order 1502. Natural Lighting. (a) Windows, skylights or other roof-lighting construction of buildings shall be arranged with the glass area so appor- tioned that at the darkest part of any working space, when normal exterior daylight conditions obtain (sky brightness of 1.50 candlepower per square inch) there will be available a minimum intensity equal to twice that of Order 1503, other- wise artificial light of intensities specified in Order 1503 shall be provided. (&) Awnings, shades, diffusive or refractive window glass shall be used for the purpose of improving daylight conditions or for the avoidance of eyestrain wherever the location of the work is such that the worker must face large window areas through which excessively bright light may at times enter the building. NOTE. The intensity requirements for adequate day lighting are much higher than those for adequate night lighting, because in general under daylight conditions the light reaching the eye from all surroundings in the field of vision is much brighter than at night, and hence a correspondingly more intense light must fall on the object viewed. Order 1503. Artificial Light. (a) When the natural light is less than twice the minimum permissible intensities of illumination set forth in the following table, artificial light shall be supplied and maintained in accordance with the table. NOTE. See Appendix for intensities recommended for best working conditions. Foot-candles at the floor level 1. Roadways and yard thoroughfares 0.02 2. Storage spaces, stairs, stairways, halls, hallways, passageways, aisles, exits and elevator en- trances 0.25 3. Water-closet compartments, toilet rooms, wash- rooms, dressing rooms and elevator cars 0.50 b GENERAL LIGHTING SAFETY ORDERS. Foot-candles at the work 4. Work not requiring discrimination of detail, such as handling material of a coarse nature, and performing operations not requiring close visual application 0.50 5. Eough manufacturing requiring discrimination of detail, such as rough machining, rough assem- bling, rough bench work, also work in base- ments of mercantile establishments requiring discrimination of detail 1.00 6. Rough manufacturing requiring closer discrim- ination of detail, such as machining, assembly and bench work, also work in basements of mercantile establishments requiring closer dis- crimination of detail, intermediate between 5 and 7 2.00 7. Fine manufacturing, such as fine lathe work, pat- tern and tool making, also office work, such as accounting and typewriting 3.00 8. Special cases of fine work, such as watchmaking, engraving and drafting 5.00 9. Processes otherwise safeguarded in which light is detrimental i 0.00 NOTE. Some exceptions to the intensity rule : (a) There are some operations that are performed in compar- ative darkness, as for example, photographic processes in the dark room. (6) There are some operations that are best observed by their own light, as in parts of the process of working glass. (c) Some^ operations are best observed by the "silhouette" method of lighting in which the work is seen against a lighted background in a comparatively dark room, as in some processes of working with dark threads and lamp filaments. In all such cases in which work is of necessity carried on in comparative darkness, special precautions should be taken to properly safeguard the workmen. Order 1504. Measurements. (a) For the purpose of light measurements, a standardized photometer, certified by the Industrial Accident Commission of the State of California, shall be used, and such measurements shall be made at the locations specified in the table. Order 1505. Shading of Lamps for Overhead Lighting. (a) Lamps suspended at elevations above eye level less than one-quarter their distance from any positions at which work is performed, or where places are traversed, must be shaded in such a manner that the intensity of the brightest one-quarter square inch of visible light source shall not exceed seventy-five candlepower per square inch. GENERAL LIGHTING SAFETY ORDERS. 7 NOTE. The following diagram illustrates the application of the above rule, the distances being explanatory and representing the ratio between the height of the lamp above the eye level and its horizontal distance from the eye. L /nz -7 L a/npj be/o w the l/rr?/ there shown ft 02 td/s fa/rt must" be 3O -shaded thaf the. Casrd/e Power o fthe brtghfes t 3

-47f 10 GENERAL LIGHTING SAFETY ORDERS. APPENDIX. GENERAL INFORMATION AND SUGGESTIONS. 1. The foregoing orders give in the briefest possible form the minimum requirements of lighting in factories, mills and other work places to insure reasonable safety to workmen from accident and injurious eyestrain. General information with detailed discussion of the methods of applying the orders and of obtaining adequate illumination to insure efficient production are 'presented in this Appendix. 2. When adequate and satisfactory illumination is substi- tuted for the all too prevalent poor illumination in factories, mills and other work places, the results obtained are mutually beneficial to the employees, the employers, and the country as a whole. Under proper illumination conditions, the health, contentedness, safety and skill of the employees are maintained at a high standard, the output is increased in quantity and improved in quality, while there is a proportional reduction in the cost of each unit of finished products when it reaches the public. 3. While it is desirable to have adequate light over the working areas, it is absolutely essential for the proper results to eliminate or minimize the light which otherwise would pass directly from the lamps to the eyes of the workers ; that is, one must avoid glare which is not only fatiguing to the eye but also conducive to the incorrect estimation of sizes and locations of objects in the field of view. 4. Glare effects may be caused not only by the light reaching the eye directly from the sources having a brightness greatly in excess of that of the objects viewed, but they may be pro- duced by excessive reflection from the objects within view. In factory lighting each lamp should be so located that the eye does not see it in the ordinary course of work, and so shaded or covered that brilliant reflections are avoided. The desired result can be obtained by putting over the lamp an open shade which screens it and reflects downward much of the light which would otherwise be of either no value or actually detrimental. Another way of accomplishing the same result is to surround the lamp with a diffusing globe dense enough not to reveal the form of the actual light source within, but to give the effect of GENERAL LIGHTING SAFETY ORDERS. 11 the light pouring from the globe as a whole. Specific sugges- tions for various locations are contained in this Appendix. 5. In the following descriptive matter may be found the elements of good illumination versed in such manner that it can be understood readily by the nontechnical mind. A perusal of this subject will convince one that, aside from the humanitarian standpoint, the expense incurred in obtaining satisfactory lighting will, in practically all cases, result in good financial returns. 6. Minimum and desirable illumination. The minimum foot-candles in Order 1503 specify the lowest illumination with which the employee can be properly safeguarded against acci- dent. It is to the advantage of the employer to provide the cor- responding intensities of modern practice listed in the follow- ing table of desirable illumination, as such provision results in reduced eyestrain, greater accuracy of workmanship, increased production and less spoilage. Desirable Illumination. Foot-candles at floor level Corresponding modern minimum practice Order 1503 1. Roadways and yard thor- oughfares 0.05 to 0.25 0.02 2. Storage spaces 0.50 to 1.00 0.25 3. Stairs, stairways, halls, hall- ways, passageways, aisles, exits, elevator entrances and elevator cars 1.00 to 2.00 0.25-0.50 4. Work not requiring discrim- ination of detail 1.00 to 2.00 0.50 5. Rough manufacturing re- quiring discrimination of detail 2.00 to 4.00 1.00 6. Rough manufacturing re- quiring closer discrimina- tion of detail 3.00 to 6.00 2.00 7. Fine manufacturing, ac- counting, typewriting 4.00 to 8.00 3.00 8. Special cases of fine work___ 7.00 to 15.00 5.00 12 GENERAL LIGHTING SAFETY ORDERS. 7. Table of Recommended Intensities for Detailed Operations and Processes. (Expressed in foot-candles.) Classification. Assembling. Rough assembling 2-6 Medium assembling 3-9 Fine assembling 4-12 Extra fine assembling 7-15 Automobile manufacturing. (See machine shops, paint shops, woodworking shops, etc.) Bakeries. Mixing and baking 3-9 Banks. Clerical and private offices 4-12 Desk and cage lighting 4-12 General illumination 1-3 Barber shops 4-12 Boiler, engine rooms and power houses. Boiler rooms 2-4 Coal and ash handling 2_4 Engine rooms 3-9 Auxiliary equipment 2-6 Oil switch and transformer rooms 3-9 Switchboards 3-9 Storage battery rooms 2-6 Brewing, distilling and bottling. Beer boiling 2-6 Bottling 3-9 Clearing or resting and fermenting 1-3 Cool ship 1-3 Keg washing 3-9 Keg filling 3-9 Buffing and polishing. Medium work 3-9 Fine work 4-12 Button manufacturing. Grading machines, wet and dry polishing 1-3 Grinding machines, cutting blanks and shells, card- ing buttons, hand turning, automatic machines 3-9 Sorting of waste, sorting for thickness 3-9 Grading for color and defects 7-15 GENERAL LIGHTING SAFETY ORDERS. 13 Classification. Candy making. Cooking over furnaces 3-9 Cooling slabs 3-9 Cream beater machines 3-9 Dipping (hand) 3-9 Dipping (machine) 3-9 Moulding 3-9 Revolving pan 3-9 Spinning bench 3-9 AWights and measures 3-9 Wrapping and packing 3-9 ('ii'inng and preserving. Cooking 3-9 Assorting, cleaning, cutting and peeling 3-9 Hand filling .__ 3-9 Machine filling 3-9 Chemical works. Furnaces 2-6 Tanks or cooking, extractors, percolators, nitrators- 3-9 Generators and stills 2-6 Drying 2-4 Evaporators 3-6 Filtration 3-6 Grinding 3-9 Crystallizing 3-6 Bleaching 3-6 Electrolytic cells 3-9 Clay products and cements. Enameling 3_9 Grinding 2-4 Filter press rooms 2-4 Moulding and pressing 3-6 Cleaning and trimming 3-6 Coloring and glazing 4-12 Kiln rooms 2-4 Kiln yards -J-2 Cloth products. fif &* Cutting 4-12 7-15 Sewing (machine) 4-12 7-15 Si-wing (hand) 4^-12 7-15 Pressing __^ 4-12 7-15 Inspecting 4-12 7-15 Cl>th treating (oilcloth, etc.) 3-9 4-12 14 GENERAL LIGHTING SAFETY ORDERS. Classification. Construction Building, railway, tunneling, etc. Indoor 1-3 Outdoor -2 Dairy products. Separators, evaporators, churns, moulds and presses 3-9 Pasteurizing 3-9 Bottling, canning and labeling 3-9 Ice cream freezers 3-9 Depots. Baggage rooms 1-2 Dining rooms 3-6 General offices 4-8 Waiting rooms 2-4 Loading platforms 1-2 Draughting rooms 7-15 Electric manufacturing. Coil and armature winding 4-12 Mica working 4-12 Insulation moulding 4-12 Other insulating processes 4-12 Storage battery moulding of grids 3-9 Lamp manufacturing 7-15 Wire insulating 4-12 Elevators. Freight and passenger 1-3 Fertilizer manufacturing. Cookers, pressers, fertilizer dryers, fertilizer mills- 2-6 Forge shops and welding. Rough forging 2-6 Fine forging 3-9 Drop forging 3-9 Foundries. Rough moulding 2-6 Fine moulding 3-9 Core making 3-9 Charging floor 2-4 Tumbling and cleaning 2-6 GENERAL LIGHTING SAFETY ORDERS. 15 Classification. Glass works. Mix room 2-6 Furnace room 2-6 Casting and lehr 2-6 Grinding 3-9 Fine grinding and polishing 4-12 Glass-blowing machines 39 Cutting glass to size 3-9 Glass cutting (cut glass) 7-15 Beveling 4-12 Silvering 3-9 Inspecting 7-15 Etching and decorating 4-12 Glove manufacturing. goods. goods. Sorting 1 4-12 7-15 Cutting 3-9 4-12 Stitching 4-12 7-15 Trimming and inspecting 4-12 7-15 Pressing 3-9 4-12 Knitting 3-9 4-12 Grinding, buffing and polishing. Rough work 2-6 Medium work 3-9 Fine work 4^-12 Halls, stairways, passageways and aisles 1-2 Eat manufacturing. Forming, sizing, pouncing, flanging, finish- ing and ironing 3-9 4-12 Dyeing and stiffening 2-6 3-9 Braiding 2-6 3-9 Cleaning and refining 2-6 3-9 Sewing 4-12 7-15 Hospitals. Corridors 0.5 "Wards, general (supplemented by local) 0.5 Wards, with no local lighting 1-3 Laboratories , 3-6 Operating tables 25-40 (See boiler and engine rooms, laundries, kitchens, dining rooms, storage spaces, etc.) 16 GENERAL LIGHTING SAFETY ORDERS. Classification. Hotels. Kitchens 2-6 Dining rooms 3-6 (See engine and boiler rooms, offices, storage spaces, stairways, passageways, laundries, etc.) Ice making 2-6 Inspecting. Rough inspecting 2-6 Medium inspecting 3-9 Fine inspecting 412 Extra fine inspecting 7-15 Jewelry and watch manufacturing. Bench work and extra fine machine work 715 Machine work 715 Stamping 7-15 Engraving 7-15 Jewel working 7-15 Laundries and dry cleaning. Sorting and marking 3-9 Washing 2-6 Mangles and machine ironing 3-9 Pressing and hand ironing 39 Dry and steam cleaning 3-9 Leather manufacturing. Cleaning, tanning, stretching, etc 2-6 Cutting, fleshing and stuffing 3-9 Finishing and scarfing 4-12 Vats 1-3 Leather working. * * Grading and matching 412 7-15 Cutting and scarfing 4r-12 4-8 Sewing 4-12 7-15 Pressing and winding 3-9 4r-12 Libraries 3-6 (See other classifications relating to corresponding quarters. ) Locker, toilet and wash rooms^^ : - 2-4 GENERAL LIGHTING SAFETY ORDERS. It Classification. Machine shops. Rough bench and machine work 2-6 Medium bench and machine work 3-9 Fine bench and machine work 412 Extra fine bench and machine work 715 Automatic machines (ordinary) 3-9 Automatic machines (fine) 4-12 Grinding, buffing and polishing, rough work 3-9 Grinding, buffing and polishing, medium work 4-12 Grinding, buffing and polishing, fine work 7-15 Meat packing. Slaughtering 2-6 Cleaning and cutting 3-9 Cooking 3-9 Grinding and packing ^ 3-9 Canning 3-9 Milling and grain food products. Cleaning 2-6 Grinding or rolling 2-6 Baking or roasting 3-9 Mining. (See boiler and engine rooms, power houses, halls, stairways and passageways, roadways, yard thor- oughfares, etc.) Offices 4-12 Oil refining. (See boiler and engine rooms, power houses, road- ways, yard thoroughfares, chemical works, etc.) Packing. Rough 2-6 Medium 3-9 Fine 4-12 Paint manufacturing 2-6 Paint shops. Dipping or spraying 3-9 Rubbing 3-9 Firing 2-6 Hand painting and finishing, ordinary 3-9 Hand painting and finishing, fine 4^12 Hand painting and finishing, extra fine (automobile bodies, piano cases, etc.) 7-15 3-47806 18 GENERAL LIGHTING SAFETY ORDERS. Classification. Paper 'box manufacturing. &>oas. goods. Cutting 2-6 3-9 Machine folding 2-6 3-9 Hand folding 2-6 3-9 Pasting and assembling 2-6 3-9 Paper manufacturing. Beaters 2-6 Calendering 3-9 Machine 3-6 Grinding 2-6 Finishing, cutting and trimming 4-12 Plating. Plating 3-9 Polishing and burnishing 3-9 Printing industries. Linotype and monotype 7-15 Typesetting 7-15 Composing stone 7-15 Matrix and casting 3-9 Miscellaneous machines 3-9 Proofreading 4-12 Presses, job and small automatic 3-9 Presses, rotary, flat-bed, etc 3-9 Lithographing 4-12 Electrotyping 4-12 Engraving 7-15 Receiving and shipping 2-6 Restaurants (see hotels). Roadways and yard thoroughfares 0.05-0.25 Rubber manufacturing and products. Calendering 3-9 Grinding 3-6 Vulcanizing 3-6 Washing and compounding rolls 3-9 Schools. Auditoriums 2-4 Blackboards 3-5 Classrooms, study rooms, libraries, laboratories 3-9 Gymnasiums '. 3-6 Sewing, drafting 7-15 Shop work (rough) 2-6 Shop work (fine) 4-12 Stairways, corridors, toilets, hat and cloakrooms, etc. 1-2 Storage spaces 0.5-1 GENERAL LIGHTING SAFETY ORDERS. 19 Classification. Sheet metal working. Bench work, ordinary 3-9 Bench work, fine 4-12 Punches, presses, shears, stamps and welders 4-12 Spinning 4r-12 Miscellaneous machines 3-9 Shipbuilding. ( See machine shops, sheet metal working, roadways, yard thoroughares, woodworking, assembling, etc.) 07 , Light Dark Shoe manuactunng. goods, goods. Inspecting and sorting raw material 4-12 7-15 Cutting 4-12 4-8 Stitching, machine 7-15 7-15 Stitching, hand 4-12 7-15 Lasting and welding 4-12 4-8 Hand turning 3-9 3-9 Miscellaneous bench and machine work 3-9 4-12 Soap manufacturing. Kettle houses 2-6 Framing 1-3 Cutting 2-6 Stamping, wrapping and packing 3-9 Soap chip 2-6 Soap powder 2-6 Filling and packing soap powder 3-9 Stairways (see halls) . Steel and iron mills, bar, sheet and wire products. Automatic machines 3-9 Charging floor 2-4 Casting floor 2-4 Soaking pits and reheating furnaces 2-4 Rolling mills 3-9 Shears, presses, punches and riveters 3-9 Rod mill 3-9 Wire drawing, coarse 3-9 Wire drawing, fine 4-12 Pickling and cleaning 2-6 Stone cutting. Machine cutting 2-6 Hand cutting 2-6 Carving 3-9 Polishing 3-9 20 GENERAL LIGHTING SAFETY ORDERS. Classification. Store and stock rooms. Rough stock 2-6 Medium stock 3-9 Fine stock 4r-12 Stores. (Satisfactory store lighting requires that considera- tion be given so many different factors, such as location, color of finish, size and shape, location and character of displays, as to make it impossible to compile a complete list. The following tabu- lation is general, only, and it is recommended that expert advice be obtained where any doubt exists as to the proper allowances to be made.) Automobile showrooms - 3-9 Art (light on exhibits) 5-10 Book 3-9 Baker 2-6 Butcher 2-6 China 3-9 Cigar 4-6 Clothing 4-12 Cloak and suit 4-12 Candy 3-6 Confectionery 3-6 Decorator 4r-12 Department (see each department). Drug 2-6 Dry goods 4-12 Florist 2-6 Furniture 3-9 Furrier 4-12 Grocery 26 Haberdasher (men's furnishings) 4-12 Hardware 2-6 Hat 4-12 Jewelry 4-12 Millinery 4-12 Music 2-6 Notions 3-9 Piano 3-9 Rug racks 10-20 Shoe 2-6 Stationery 2-6 Tailor 4-12 Tobacco (see cigars). GENERAL LIGHTING SAFETY ORDERS. 21 Classification. Sugar refining. (See boiler and engine rooms, power houses, halls, passageways, chemical works, etc.) Telegraph. Operating __ 4-12 Telephone. Automatic exchanges 4-12 Manual exchanges 3-9 Testing. Rough 2-6 Medium 3-9 Fine 4-12 Extra fine 7-15 Textile mills. n Light Dark OOttOn goods. goods. Opening and lapping 2-6 2-6 Carding 2-6 2-6 Drawing frame - 26 26 Roving, spooling, spinning, etc 3-9 3-9 Warping 2-6 2-6 Slashing 2-6 2-6 Drawing in 3-9 3-9 Weaving 3-9 3-9 Dyeing 3-9 3-9 Silk Winding 3-9 3-9 Throwing 3-9 3-9 Quilling and warping 3-9 4-12 Weaving 3-9 4-12 Dyeing 3-9 3-9 Finishing 3-9 4-12 Woolen Picking 3-9 3-9 Washing and combing 3-9 3-9 Carding 2-6 2-6 Twisting 3-9 3-9 Dyeing 3-9 3-9 Drawing in 3-9 4-12 Warping 3-9 4-12 Weaving 4-12 7-15 Perching 7-15 7-15 Knitting machines, ordinary and nappers 3-9 3-9 Knitting machines, flat and others 4-12 4-12 Cordage mills __, 3-9 3-9 22 GENERAL LIGHTING SAFETY ORDERS. Classification. Tin can manufacture. (See sheet metal working, machine shops, etc.) Tobacco products all operations 3-9 Warehouses 2-4 (See other classifications.) Woodworking. Rough sawing (sawmills) 2-6 Sizing, planing, rough sanding, etc 3-9 Machine woodworking, medium 3-9 Machine woodworking, fine 4-12 Bench work, medium 3-9 Bench work, fine 4-12 Fine sanding and finishing 4-12 Gluing and veneering 3-9 Cooperage 3-9 DAYLIGHT. 8. Importance of daylight. Adequate daylight facilities through large window areas, together with light, cheerful surroundings, are highly desirable and necessary features in every work place, and they should be supplied through the necessary channels not only from the humane standpoint, but also from the point of view of maximum plant efficiency. The unusual attention to gas and electric lighting in factories, mills and other work places during the past few years ; the perfection of various lamps and auxiliaries by means of which an improved quality and quantity of lighting effects are obtained; and the care which has been devoted to increasing the efficiency in various industrial operations all go to emphasize the many advantages and economies that result from suitable and ade- quate window space as a means for daylight in the proper quantities and in the right directions during those portions of the day when it is available. 9. Three considerations. Three important considerations of any lighting method are sufficiency, continuity and diffusion. With respect to the daylight illumination of interiors, suffi- ciency demands adequate window area; continuity requires (a) large enough window area for use on reasonably dark days, (6) means for reducing the illumination when excessive, due to direct sunshine, and (c) supplementary lighting equipment for GENERAL LIGHTING SAFETY ORDERS. 23 use on particularly dark days and especially toward the close of winter days; diffusion demands interior decorations that are as light in color as practicable for ceilings and upper portions of walls, and of a dull or mat finish in order that the light which enters the windows or that which is produced by lamps, may not be absorbed and lost on the first object that it strikes, but that it may be returned by reflection and thus be used over and over again. Diffusion also requires that the various sources of light, whether windows, skylights or lamps, be well distrib- uted about the space to be lighted. Light colored surroundings as here suggested result in marked economy, but their main object is perhaps not so much economy as to obtain a result that will be satisfactory to the human eye. 10. Requirements. The following requirements may now be listed for natural lighting: 1. The light should be adequate for each employee. 2. The windows should be so spaced and located that daylight conditions are fairly uniform over the working area. 3. The intensities of daylight should be such that artificial light will be required only during those portions of the day when it would naturally be considered necessary. 4. The windows should provide a quality of daylight which will avoid a glare due to the sun's rays and light from the sky shining directly into the eye, or where this does not prove to be the case at all parts of the day, window shades or other means should be available to make this end possible. 5. Ceilings and upper portions of walls should be maintained a light color to increase the effectiveness of the lighting facil- ities from window areas. The lower portions of walls should be somewhat darker in tone to render the lighting restful to the eye. Factory green or other medium colors may be used to good effect. 11. Classification. Means for natural lighting may be classed under three broad divisions as follows : (a) That case in which the windows are located on the sides of the building or in the framework of saw-tooth construction where diffused light from the sky reaches the work during a large portion of the day. (&) That case in which windows are located overhead on a horizontal or nearly horizontal plane in the form of skylights, 24 GENERAL LIGHTING SAFETY ORDERS. thus furnishing direct light from the sky during a large portion of the day. (c) That case in which prismatic glass takes up the direct light from the sky and redirects it into the working space. Method (a) is, of course, the most common of the three, and it may be noted that the saw-tooth or other roof -lighting con- structions have become very popular and result in an excellent quality and quantity of light for given window areas, provided the size and location of windows are in accord with modern practice. 12. Increasing the value of floor space. Adequate and well distributed natural light means that certain portions of the floor space which ordinarily would not be available for work, are converted into valuable manufacturing space. In a gen- eral way, therefore, the average factory, mill or other work place, if properly designed, should possess natural lighting facilities which produce the best practicable distribution of daylight illumination. 13. Wide aisles. With low ceilings and very wide aisles, workmen located at the central portion of the building must sometimes depend for their natural light on windows located at a considerable distance away from their working position. In these cases it may be possible, in general, to depend alto- gether on daylight over an entire floor space, even at those times of the day when daylight conditions would be entirely adequate under other circumstances. This statement applies to side windows rather than to skylights or to saw-tooth con- struction. Fig. 1 illustrates this feature. 14. Varying conditions. In a case of this kind, employees located next to the windows are furnished with suitable day- light in the early morning and towards the latter part of the afternoon, the upper portions of the windows being particu- larly serviceable in lighting areas at some distance away from the windows. A southern exposure, however, results in such excessive light from the sky during the middle of the day, that heavy shades are nearly always pulled down so as to cover the entire window area. This plan makes it necessary to use arti- ficial light throughout the larger part of the office during the brightest portion of the day, and reduces the daylight at those points where it would supposedly be the best, namely, near the GENERAL LIGHTING SAFETY ORDERS. 25 windows. Here the location of the windows is a large factor in the excellence of the daylight conditions, but the manipula- tion of the shades is perhaps even more important. To avoid such difficulty, adjustable translucent upper window shades with adjustable opaque lower shades might be employed. REGION OFCOM- PARITIVE ABSENCE OF DAYLIGHT. ARTI- FICIAL DAYLIGHT REQUIRED NEARLY ALL DA.Y ELEVATION /DESKS-, 000 O O -50' 000 PLAN FIG. 1. Diagram of a large office with windows on one side only. 15. Upper portions of windows. It should be further noted in this illustration that the upper portions of the windows give a reduced illumination in proportion to their areas, to the floor space near them. In rooms of moderate size, therefore, the windows should be placed as near the ceiling as practicable. When the sun shines* through windows so located, the direct light must be reduced or diffused. This may be accomplished by the use of ribbed glass in ordinary factory and mill build- ings, and in offices by the use of translucent sunshades or awnings. 16. Tempering the light. The light due to the sunshine on such shades and awnings will be as bright as ordinary skylight if the shade is well chosen, and the ribbed glass will be still brighter. If the windows are large, the illumination is likely 4 478C6 26 GENERAL. LIGHTING SAFETY ORDERS. to be too great near the windows as previously pointed out and it should be reduced. This should not be done, however, by pulling down an opaque shade over the top of the windows because the top portion of the window is the part that is par- ticularly needed to give light to the interior of the room. The better scheme is to employ an opaque shade which should be raised from the bottom of the window. This will reduce the illumination near the window without affecting it over the interior of the room to any marked degree. 17. Bench locations. Fig. 2 shows how benches are com- monly located with respect to windows, so that the light received on the work may be most satisfactory. This sets a certain < CEILING-* | 7Q . BENCH SURFACE- ] ASSEMBLY WORK; ^^~" \ "1 / },>;;,, '< ELEVATION '! 1 "VBENCH-I -i - u li I + J ( ! 1] 1 * - V -BENCH-, 1 - * l 1 ///S//SS/S/////J//) PLAN FIG. 2. Diagram showing benches located with respect to the windows so as to receive the natural light advantageously. limitation upon the possible arrangement of the work over the floor space, depending on the way daylight is furnished to the floor area. This limitation can be eliminated almost com- pletely in the case of artificial light through a uniform dis- tribution of lamps overhead. This statement applies to those cases where natural light is transmitted through side windows, and includes a feature specially noticeable in buildings of more than one story. In contrast, the work may be arranged almost independently of the natural light in buildings where the natural light is furnished by overhead windows or through the means of saw-tooth construction. 18. Window glasses. Both translucent and clear glass are employed for factory and mill windows. There is a slight reduction in the transmitted light through ordinary translucent GENERAL LIGHTING SAFETY ORDERS. 27 vvire glass, but it is often required by insurance regulations for a deduction in the fire risk where a given building is located in close proximity to other buildings. Wire glass is also used quite generally with steel window frames, here being an added protection from the standpoint of fire risk. Wire glass may be obtained in clear form, but its expense in contrast to the translucent form is such as ordinarily to prohibit its use for industrial purposes. 19. Wire glass. Wire glass, also known as ribbed glass, should be used and is advocated for practically all factory and mill windows where prisms are not required. Wires of rather open mesh cause so little reduction in light as to warrant no mention of this .feature. Special care should be taken to get such glass as is smooth both on the flat side and on the ribbed side to facilitate cleaning. Wire or ribbed glass gives better diffusion than plain glass. 20. Prism glass. Where the sky outside of the windows is obstructed by buildings, prism glass is recommended if the room is deep. Different kinds of prisms can not be used to advan- tage interchangeably. The amount of prism glass required in any case depends much upon the surroundings and to obtain excellent results, of which such glass is capable, it must be used intelligently. 21. Skylights. Skylights are sometimes installed in long narrow continuous strips in a sloping roof. The ribs of the ribbed glass are generally so arranged that it is convenient to make them at right angles to the length of the strips. The result is that the sunshine is diffused by the ribs over a narrow area parallel to the strip of skylight, thus lighting one part of the room much more brilliantly than the remainder. If the ribs are installed to run parallel to the strips, they will give a much more general distribution of the sunlight. In the foregoing, the word strip refers to the long belt of skylight and not to the individual sheet of glass. Ribbed glass in vertical windows should generally be placed with the ribs horizontal. They thus roughly fulfill some of the functions of prisms. 22. Dirt accumulations. While translucent wire or ribbed glass reduces the amount of light transmitted through the windows, the roughness of the outside surface of such glass often causes accumulations of dust and dirt, which are more 28 GENERAL LIGHTING SAFETY ORDERS. to blame for the reduction of transmitted light in some cases than the translucent nature of the glass itself. Remedies of this difficulty are to secure smooth glass and to resort to frequent cleaning. 23. Wire glass as a safeguard. Wire glass for skylights is, of course, a practical necessity as a safeguard against accidents due to accidental breakage of the glass or due to objects falling on top of the glass. 24. Sunshine not desirable. In all the work of providing natural light, it should be kept in mind that direct sunshine in itself, from the illumination standpoint, but irrespective of sanitary conditions, is not wanted. The idea that sunshine is the important item is a common but an erroneous impression. For example, in saw-tooth construction, the windows do not face the south to get all the sunshine possible, but they face the north to exclude the sunshine. Ordinarily windows, on the other hand, face all directions because not enough light can be distributed to interiors from north windows alone. Windows on the other than north fronts admit sunshine to be sure, and this makes sun shades and awnings necessary to exclude the excessive brightness. VALUE OF ADEQUATE ILLUMINATION. 25. Factory and mill owners are concerned in the matter of securing the largest output for a given manufacturing expense. An improved machine tool capable of increasing the product for given labor costs is most attractive, provided its first cost is within returnable limits out of the larger profits. Improved small tools, better methods of handling material, adequate crane service, fire protection, good shop floors, accurate and efficient timekeeping methods, and similar items, vitally concern the shop manager ; money is expended to realize excellence in these features because they afford increased economies and protection, thus resulting in a higher efficiency of the plant. 26. Energy consumption a minor item. Many arguments leading to the sale of gas and electric lamps for use in factory and mill buildings are based on reducing the lamp operation cost of substituting a new for an older system. Arguments of this kind are of value, however, only when such a reduction GENERAL LIGHTING SAFETY ORDERS. 29 in operation cost can be effected without sacrifice in the ade- quacy of the illumination. It would be a poor policy, in the extreme, to argue a saving in energy consumption by the sub- stitution of one type of lamp for another on a basis of equal candlepower in both old and new systems. 27. Effect of good light on production. Arguments of a convincing nature, which insure to the factory or mill man- ager an increased output through improved illumination service, are of importance and even greater at times than reductions in the cost of illumination for the same quantities of light. In view of the fact that resulting advantages of superior illumination on increased output are apt greatly to exceed economies in operation cost as regards the lighting system, it is a distinct advantage to direct and hold the atten- tion on the former rather than on the latter. This statement will be more apparent when interpreted into definite items as follows: 28. Advantages of good light. While the necessity of good natural and artificial light is so evident that a list of its effects may seem commonplace, these same effects are of such great importance in their relation to factory and mill management, that they are well worth careful attention. The effects of good light, both natural and artificial, and of bright and cheerful interior surroundings, include the following items: 1. Reduction of accidents. 2. Greater accuracy in workmanship. 3. Increased production for the same labor cost. 4. Less eyestrain. 5. Promote better working and living conditions. 6. Greater contentment of the workmen. 7. More order and neatness in the plant. 8. Supervision of the men made easier. In this list it will be noted that items 4, 5, 6, 7 and 8 all have a bearing on accident prevention. 29. Interpreting the advantages of good light. While the major consideration in the eyes of the factory or mill owner is undoubtedly and quite naturally the money value of good light in the larger return of both quantity and quality of work which may result from the installation of a superior as com- pared with an inferior lighting system, it should be noted that it is very difficult to interpret into dollars and cents the value 30 GENERAL LIGHTING SAFETY ORDERS. of good light made possible by such returns. This difficulty is due to the necessity of keeping all conditions in a factory or mill section absolutely constant while varying the amount of illumination from poor to good conditions, in an effort to determine the output and its dependency on the light facilities. As accurate data becomes available, giving the increases in production for certain specific improvements in artificial light- ing, it will doubtless prove helpful to a proper interpretation of adequate light and its worth to any plant. The eight foregoing points are emphasized as forming the most important features in the problem of good lighting. Although difficult to interpret into money values, and some- what intangible, they are indisputable arguments in favor of the best available illumination from the standpoint of the factory or mill owner. 30. Practical example. Continuing from the manufacturer 's point of view, it may be said that certain assumptions as to energy cost, cleaning, interest and depreciation, show that the annual operation and maintenance cost for the illumination of a typical shop bay of 640 square feet area, may be taken at $50.00. If five workmen are employed in such a bay at an average wage of say 25 cents per hour, the gross wages of the men in such a bay, plus the cost of superintendence and indi- rect shop expense, may equal from $5,000 to $7,000 per annum. In a case of this kind, therefore, the lighting will cost from fa to 1 per cent of the wages, or the equivalent of less than 4 to 6 minutes per day. We may roughly say that a poor lighting system will cost at least one-half this amount (some- times even more through the use of inefficient lamps and a poor arrangement of lamps), or the equivalent of say 2 to 3 minutes per day. Nearly all factories and mills have at least some artificial light, hence, in general, if good light enables a man to do better or more work to the extent of from 2 to 3 minutes per day, the installation of good lighting will easily pay for the difference between good and bad light, through the time saved for the workmen. 31. Actual losses. Superintendents have stated in actual instances, that due to poor light their workmen have lost much time, sometimes as much as from one to two hours per day on certain days. If good light will add an average of say one- half an hour per day to the output, these 30 additional effective GENERAL LIGHTING SAFETY ORDERS. 31 minutes represent an increase in output of 5 per cent, brought about through an expenditure equal to \ of 1 per cent of the wages for improved lighting, or a saving equal to ten times the expense. OLD AND NEW LAMPS. 32. The inadequate means available for illumination by artificial methods in the past have contributed to the slowness of an appreciation of the features of artificial light which influence the working efficiency of the eye. Open flame gas burners, carbon incandescent and arc lamps, practically the only illuminants available ten years or so ago, play but a small part in the present approved methods of factory and mill lighting. 33. New lamps. The large variety of comparatively new lamps available for factory and mill lighting includes the mercury vapor, tungsten, gas-filled tungsten, metallic flame or magnetic arc, the flame carbon arc, the quartz mercury vapor, and various types of gas arc lamps. Remarkable improvements have thus been made in both the electric and gas lighting fields, the same general rules of applying the lamps covering both of these fields. Possibilities in factory and mill lighting are now attainable which, before the intro- duction of these new lamps, were either unthought of or impossible. Consideration of the eye as a delicate organ, together with the new ideas of the items which affect its comfort and efficiency, have resulted in establishing certain principles in illumination work, and have directed attention naturally and in a growing manner to the proper use and application of these new lamps. EFFECTS ON FACTORY AND MILL LIGHTING PRODUCED BY MODERN LAMPS. 34. With the introduction of these new gas and electric lamps, broader possibilities have been presented in factory and mill lighting. The use of units of sizes adapted to the purposes, allows results which it has been hitherto impossible to obtain satisfactorily, either by the arc lamp, carbon filament or open flame gas burner, formerly available. 32 GENERAL LIGHTING SAFETY ORDERS. 35. New possibilities. It is evident that the introduction of the many new lamps has made possible what may be termed a new era in industrial illumination, a distinctive feature of which is the scientific installation of the lighting units, suiting each to the location and class of work for which it is best adapted. Before the availability in recent years of medium sized gas and electric units the choice of the size of unit for a given location was often no choice at all. In many cases, due to small clearance between cranes and ceilings, or other con- ditions making it necessary to mount the lamps very high above the floor, but one size or type of unit was available, the carbon filament or open flame gas burner in the former, and the arc lamp in the latter case. 36. Low ceilings. For low ceilings, up to 18 feet, the use either of carbon filament, open flame gas burner, or arc lamps resulted usually in anything but uniform light over the work- ing plane, and often produced merely a low general light which was practically useless for the individual machine. In such instances, individual lamps had to be placed over and close to the machines. With this arrangement, a relatively small area is lighted by each lamp and the metal shades usually employed serve only to accentuate the "spot lighting" effect. Such a form of illumination for factory and mill work is unsatisfactory and inefficient, but, as stated, was in the past in many cases the only available scheme. The absence of lamps of the proper size is no longer an excuse for the exist- ence of such conditions in industrial plants. GENERAL REQUIREMENTS OF ARTIFICIAL LIGHTING. 37. The following requirements for factory and mill lighting are made all the more important by the peculiar limitations and the wide variety of conditions to be found in factory and mill buildings and in factory and mill work : 1. Sufficient illumination should usually be provided for each workman irrespective of his position on the floor space. 2. The lamps should be installed and selected so as to avoid eyestrain to the workmen. 3. The lamps should be operated from sources of supply which will insure reliable illumination results, particularly on account of the demoralizing effect by intermittent service, just when the light may be most needed. GENERAL LIGHTING SAFETY ORDERS. 33 4. Adequate illumination should be provided from over- head lamps so that sharp shadows may be prevented as much as possible, and in such measure that individual lamps close to the work may be unnecessary except in special cases. 5. The type and size of lamp should be adapted to the particular ceiling height and class of work in question. 6. In addition to the illumination provided by overhead lamps, individual lamps should be placed close to the work if they are absolutely necessary in the eyes of a lighting expert, and in such cases the lamps should be provided with suitable opaque reflectors. These requirements may now be met by means of the new types of gas and electric lamps, one type of which can usually be found for practically each factory and mill location, espe- cially adapted to the general physical conditions of the location as typified by the clearance between cranes and ceiling and other similar items. OVERHEAD AND SPECIFIC METHODS OF ARTIFICIAL LIGHTING. 38. Factory and mill lighting may be classified under two general divisions: First, distributed illumination furnished from lamps mounted overhead ; and second, distributed illumi- nation furnished by individual lamps located close to the work. For practical purposes this classification is sufficient. In numerous cases a combination of these two methods becomes necessary. 39. Mounting the lamps high. Where the lamps are high enough to be out of the line of ordinary vision, and are of a size and so spaced as to furnish illumination at any position on the floor where work may be carried on, the system is referred to as the overhead method of lighting. This method has many advantages. Its general adoption, which has been somewhat slow, has increased with the appearance of the many new types of lamps and with the growing appreciation of the value of good lighting. 40. Where a small amount of general or overhead lighting is coupled with specific lighting from. individual lamps, a large part of the floor space in many shops is in relative darkness, and much dependence must be placed on the hand lamps close to the work. The small number of overhead lamps generally 34 GENERAL LIGHTING SAFETY ORDERS. used in such cases furnishes merely a small amount of addi- tional illumination over the floor space which is not sufficient to be of much value. However, where sufficient intensity is provided by general illumination, this is often a very effective means of lighting a large workroom. 41. Low ceiling. Locations with low ceilings, until recently, have been lighted by the individual hand lamp method, because the old carbon filament lamps, being of low candlepower, could not well be used close to the ceiling, while the old type of arc lamp was often impracticable, due to its large physical size, as well as its relatively high candlepower. This statement is subject to some modification, because low candlepower units have sometimes been used in clusters for low ceilings as a com- promise between a single small or a single large unit, this scheme being, however, usually insufficient and unsatisfactory in comparison with modern methods of lighting. In a partic- ular manner, therefore, suitable illumination has been difficult with low ceilings. 42. New types of gas and electric lamps have a range of candlepower from very low to very high values, and the over- head system with the elimination of individual lamps is thus possible ; in other words, a size of gas or electric lamp may now be selected from a large available list of sizes for nearly every factory or mill condition. VARIOUS LOCATIONS ILLUSTRATED.* 43. Figs. 3 to 12 inclusive are given to indicate how the problem of adequate illumination has been solved in a number of actual instances, and the following notes apply to some of the considerations involved. There are two main items to consider in deciding for or against high candlepower lamps for the factory or mill. First, how high are the lamps to be mounted; and second, will the light at any given point on the machines or other operations be satisfactory if it comes from a few lamps or should it come from many sources? If the ceiling or overhead construction is under 16 feet, lamps of high candlepower can hardly be used in sufficient numbers to produce uniform illumination over the floor space. If they are to be mounted at a height *Figs. 8 to 12 inclusive are, in general, arranged in the order of their mounting heights. The low mounting heights are shown in the earlier illustrations and the higher mountings in the later views. GENERAL LIGHTING SAFETY ORDERS. 35 between 16 and 25 feet, it is largely a question of whether light from a relatively few lamps will produce satisfactory results. For mounting heights over 25 feet, lamps of high candlepower possess some advantages, chief of which is their large volume of light for given energy consumed, always pro- vided the light is effectively directed towards the floor. 44. Three groupings. These three groupings by mounting heights are conveniently shown in Figs. 15, 16, 17 and 18. In Fig. 15, a single shop bay with a ceiling height of 12 feet is shown as typical of the first grouping. The single high candle- power lamp furnishes approximately the same amount of light to the machines as do the eight small lamps. Note, however, that the illumination from the large lamp is not nearly as uniform as that from the small lamps, although the spacing of both the small and the large lamps as represented in this illustration is typical of many actual installations. Note also that the shadows cast by the large lamp at certain portions of the floor space must be so marked as to make the illumination it furnishes very inferior in this respect to the illumination from the smaller lamps, because of their larger number. Here, if the number of large lamps for the given floor area be increased in an endeavor to make the illumination more uni- form and to reduce the shadows, the expense as compared with that for smaller lamps, makes the large lamps a very unfavor- able proposition. These two features are the basis for stating that in general large lamps are not desirable for mounting under 16 feet, and an analysis of conditions, together with a. careful and unbiased comparison with the illumination produced by smaller lamps, will nearly always bear out this conclusion. 45. Second grouping. In Fig. 17, a 20-foot ceiling has been selected as typical of the second grouping, a single shop bay being shown. Here the work is assumed to be rough assembly, mostly on horizontal surfaces, and the single high candlepower lamp, besides giving more nearly uniform illumination, because the light is distributed more broadly due to the increased height, is correspondingly more satisfactory as to shadows produced by the large lamp in the preceding illustration (Fig. 15), on account of the improved direction in which much of the light reaches the work. In this case, the arrangement 36 GENERAL LIGHTING SAFETY ORDERS. of both large and small lamps is typical of many existing installations. 46. In Fig. 16, however, although the height is the same as in Fig. 17, the work is quite different, being conducted on the inside of large vertical tanks. It would obviously be impos- sible to perform this work by the light from the single large lamp as Well as with that from the larger number of medium sized lamps, even if the actual amount of light from each was the same, on account of the poor direction of the light at cer- tain positions of the work from a single unit in such a case. The medium sized lamps furnish approximately the same quantity of light and yet no matter where the tanks may be placed, they will receive considerable light from the medium sized lamps directly over or nearly over them, at least far more than is apt to reach them from a single unit in every other bay (the assumed arrangement of the large lamps). 47. For this second grouping of mounting heights, then, the large lamps may or may not be adapted, depending on whether the reduction of shadows is of much importance, as is the case in Fig. 16. The large lamp is, however, more likely to be satisfactory here than in the first case (Fig. 15), because of the better distribution of the light due to the higher mounting, a fact made evident in Figs. 15 and 17 on account of the decreased number of small lamps and the increase in their size made possible in Fig. 17 as compared with Fig. 15, where the mounting is lower. By the same line of argument, it can be shown that for higher mountings, large lamps are still more likely to prove satisfactory. 48. In Fig. 16, the number of large lamps might have been increased for the given floor area, but to have done so would mean that the cost for the energy and upkeep to maintain them would be excessive in comparison with the smaller types of lamps. GENERAL LIGHTING SAFETY ORDERS. 37 FIG 3 Night view of a rather low factory section showing tungsten lamps of the 100-watt size in bowl reflectors mounted 13 feet above the iloor. FiG. 4. Night view showing lighting in low store section, 400-watt tungsten lamp in 18-Inch dense semi-indirect bowls. Ceiling height 13 feet. Note the comparative absence ef shadows. 38 GENERAL LIGHTING SAFETY ORDERS. FIG. 5. An example of yard or alleyway lighting, 200-watt tungsten lamps in reflectors with a mounting height of 20 feet. Note the evenness of illumination and the absence of shadows. Twenty-five per cent of the accidents in manufacturing plants are due to poor illumination. 6. Night view of a planing mill showing an installation of 250-watt tungsten lamps with a 16 -foot mounting. Note the excellent dis- tribution of the light and the comparative absence of shadows. This is an example of the overhead method of lighting. GENERAL LIGHTING SAFETY ORDERS. 39 FIG. 7. Night view of factory section, 400-watt bowl type reflectors with 29-foot mounting height. FIG. 8. Night view of open hearth pouring floor with 750-watt reflectors, 35-foot mounting height and 40-foot spacing. 40 GENERAL LIGHTING SAFETY ORDERS. FIG. 9. Night view of factory section with relatively high mounting of 250-watt tungsten lamps. The lamps are 20 feet above the floor. Note the excellent distribution of the light and the shielding effect of the girders which serve to reduce the glare as one looks down the aisle. FIG. 10. Night view of arc lamp installation with 40-foot mounting at center of picture and 20-foot at sides. Excellent distribution. GENERAL LIGHTING SAFETY ORDERS. 41 FIG. 11. Day view of relatively high stin, showing a system of gas lighting. FIG. 12. High section showing a system of mercury-vapor lamps. Note the excellent distribution o f . light over the floor area. 42 GENERAL LIGHTING SAFETY ORDERS. FIG. 13. Bad lighting. Bare lamps produce a glare which Is harmful and renders the Illumination very ineffective. Compare with Fig. 14. Fio. 14. Example of good tungsten lighting. GENERAL LIGHTING SAFETY ORDERS. 43 )W POWER UNITS HIGH POWER UNIT ELEVATION PLAN FIG. 15. Diagram showing alternate schemes for lighting a low factory section. This contrasts the use of large and small lamps for a mounting height of 12 feet. ELEVATION '.LOW POWER UNlTi ^ 4* JHIGH POWER UNIT i >BENCHES *--4- 4 j 4 PLAN FIG. 16. Diagram contrasting the use of large and medium sized lamps for mount- ing height of 20 feet. PLAN FIG. 17. Diagram of same factory space shown in Fig. 16, but with a different class of work. This view con- trasts the use of large and medium sized lamps for a 20-foot mounting. 44 GENERAL LIGHTING SAFETY ORDERS. 49. Third grouping. In Fig. 18, the third grouping of mounting heights is shown with the lamps about 50 feet above the floor. In this illustration the distribution of the light from the large lamps will be far more satisfactory, both for flat and tall work than in the two preceding cases. It will be noted further that the increased height of the lamp causes the light to fall in such directions as to distribute it evenly over CRANE RUN-WAY- MACHINE TOOLS AND HEAVY ASSEMBLY WORK LOCATED ON THIS FLOOR AREA'^ ELEVATION [HIGH POWER UNIT _BAYJNTER5EC1IPN: -l6'-6"--->K 33-0"-- _ ; BAY INTERSECTION-... _J. BAY INTERSECTION _i 'HIGH POWER UNIT *-$ PLAN FIG. 18. Diagram showing the use of large lamps for a mounting height of 50 feet. the entire floor space taken care of by this one lamp in much better shape than for the lower mounting heights. (See also Pigs. 19 to 23, inclusive.) LIGHTING CIRCUITS FOR ELECTRIC LAMPS AND SUPPLY MAINS FOR GAS LAMPS. 50. The question of lighting circuits is mentioned here with particular reference to factory and mill conditions, where motor loads are apt to be large in comparison to the energy GENERAL LIGHTING SAFETY ORDERS. 45 consumption of electric lamps which are in service. In some cases; the proportion of motor load to lighting .load is in the ratio of 10 to 1, in others 7 to 1, and so on, and the varying demands on the circuits by motors may greatly affect the lamps. Hence it is important to maintain strictly separate supply circuits for the lamps in order to avoid varying voltage which is apt to result if the motors are connected to the same circuits with the lamps. MEZZANINE FLOOR ' & "o k HIGH POWER* UNIT INCHES-. ! 4-,8'-tf-J T ---BE ; lAISLEl i | ELEVATION <- 40'-0- > BENCH |BENCH_! VVHIGHPOWER9 >*- UNIT " BENCH |BENCH ; MEZZANINE FLOOR POWqR UNIT' l^LOWPOWERTjNIT~5 ~ BENCHES^ PLAN FIG. 19. This shows a v e r y poor arrangement of artificial light- ing by means of large lamps mount- ed too close to the floor. Compare this poor lighting scheme with the improved plan in Fig. 20. ELEVATION 40'-0"---. ; TBENCH: =0 csi TBENCH PLAN FIG. 20. This illustration is to be compared with Fig. 19. It Indicates an im- proved scheme over that shown in Fig. 19 ; made pos- sible by the use of smaller lamps. 51. Constant voltage. In addition to the superior illumina- tion resulting 'from lamps supplied from constant voltage mains, some types operate with longer life or very much better mechanically when supplied with constant voltage than other- wise. These features will therefore generally more than offset the somewhat greater cost of maintaining separate circuits for each class of service. In like manner and for similar reasons, it is advisable to place gas lamps on supply lines separate from those delivering gas for power purposes. CONTROL OF LAMPS AND ARRANGEMENT OF SWITCHES. 52. The control of lamps in factory and mill lighting is important in all cases, but specially so where a large number of lamps is used in preference to a small number for a given 46 GENERAL LIGHTING SAFETY ORDERS. J ^ > AISLE '-LOW POWER' UNITS*' T ASSEMBLY BENCH ! HERE N ^LOW POWER UNITSr''' r ^BENCHu I ; 1 \ AISLE | i | 1 \ J ELEVATION . 4 -T- ELEVATION <3 z/ UJ ' (- 00 ^ ( 0-H -4 r . ii A '** BENCH ! t ASSEMBLY 4 H<- 16-0- - * BENCH =0 t A A A BENCH ' ^ JT'*' I t t " ^.Jo 1 BENCH N -LOW POWER/UNITS '1' ^ASSEMBLY e IS'-Q 1 '---? BENCH'S