UC-NRLF ENGIN. LIBRARY B 3 112 . ricot Engineering Library THE ELECTRICAL CONTRACTOR McGraw-Hill BookCompany Electrical World The Engineering and Mining Journal Engineering Record Engineering News Railway Age Gazette American Machinist Signal Engineer American Engneer Electric Railway Journal Coal Age Metallurgical and Chemical Engineering P o we r THE ELECTEICAL CONTRACTOR PRINCIPLES OF COST-KEEPING AND ESTIMATING, WIRING AND. ILLUMINATION CALCULATIONS AND OTHER TECHNICAL PROBLEMS OF THE BUSINESS BY LOUIS W. MOXEY, JR. VICE-PRESIDENT, KELLER-PIKE CO. PHILADELPHIA, PA. FIRST EDITION McGRAW-HILL BOOK COMPANY, INC. 239 WEST 39TH STREET, NEW YORK 6]AND 8]BOUVERIE STREET, LONDON, E. C. 1916 /A Engineering Library COPYRIGHT, 1916, BY THE McGRAW-HiLL BOOK COMPANY, INC. /iu: c A < x THK MAI'LK I'KKSS YORK PA PREFACE Only a few years ago the electrical contractor was an individual mechanic. The period of evolution to the organized business of today has been too short to permit of much standardization in systems of methods of han- dling work, and many men are suffering today the costly consequences. The need of better methods in both the commercial and technical phases is evident to anyone who comes in contact with the average contractor's organization and work. In the hope that the essentials of the writer's system, developed during the past twenty years, and the tech- nical data accumulated in connection therewith, may be of assistance to other contractors, the author has ven- tured to publish this material in book form. Much of the material has already appeared in the Electrical World. L. W. M., JR. PHILADELPHIA, PA, February, 1916. 338063 CONTENTS PAGE PREFACE v CHAPTER I. Profit and Overhead Expense 1-6 II. Bookkeeping 7-13 III. Cost-keeping 14-40 IV. Estimating 41-45 V. Calculating Wire Sizes for D. C. Currents 46-52 VI. Calculating Wire Sizes for A. C. Currents 53-61 VII. Illumination Calculations 62-73 VIII. General Data 74-80 INDEX 81 vn THE ELECTRICAL CONTRACTOR CHAPTER I PROFITS AND OVERHEAD EXPENSE PROFITS The two primary requisites for achieving success in the conduct of an electrical-contracting business are a knowledge of business principles and methods and a knowledge of electrical construction and the related engineering problems. Each of these factors is of equal importance, and real success in the electrical-contract- ing business cannot be obtained if either of these two factors be lacking. Of primary importance to every contractor and every business man is the subject of profits. Every man in business desires to make a profit, but many have only a vague idea of the meaning of the word. To illustrate what is meant by the word " profit" take the case of a corporation. It has not made a profit on its year's business unless the amount of money received or assur- able of collection without cost within a reasonable length of time exceeds the amount of money expended during the year. The amount of money expended by a cor- poration doing, for example, an electrical-contracting business includes not only the amount paid for labor and material actually used on its jobs but all amounts l 2 THE ELECTRICAL CONTRACTOR paid for labor and material whether chargeable to any particular job or not. In other words, the material item should embrace the cost of engines and dynamos as well as ink and pencils, and the labor item should include not only the pay of the journeymen and helpers but also the salaries of the president and other officers. If a corporation makes a profit on its year's business only under the conditions outlined, an individual or a group of individuals can make a profit only under the same conditions. The error which many persons who do a small business make is that they fail to include in the amount of money expended for labor during the year a salary for themselves. This should be equal to the sum that they would have to pay a person or persons for doing their work and producing the same results. Hence many persons doing a small business and neglect- ing to include a salary for themselves in the labor item do not make a profit. What appears to be profit may merely be a salary perhaps meager at that. OVERHEAD EXPENSE There are two items which combined compose the cost of conducting an electrical-contracting business. These must be taken into consideration when figuring profits. The first item includes the cost of materials and labor actually used on jobs, such as engines, dy- namos, panelboards, conduit, wire, etc., together with the salaries of the foreman, journeymen, helpers and apprentices. This item may be called, for convenience, shop or raw cost. The second item includes the cost of materials and labor expended in securing a contract and in the exe- cution of the job. It embraces the salaries of the officers, PROFITS AND OVERHEAD EXPENSE 3 bookkeeper, stenographer, bill clerk, draftsman, super- intendent, etc., and the cost of rent, heat, light, taxes, insurance, stationery, postage, telephone and the like. This item is called manufacturer's expense or overhead charge. The shop or raw cost is always more or less an uncertain one and will be dwelt upon in detail in Chap. Ill, while overhead charges can be fairly well determined. From a collection of data compiled by the National Electrical Contractors' Association on the costs of con- ducting an electrical-contracting business, it appears that the overhead expense of an electrical contractor lies between about 15 and 25 per cent, of his shop cost and that the average profit is figured at from 5 to 15 per cent, of the gross cost, depending upon the terms of the contract and the nature of the work. The following outline gives a list of items which enter into a contractor's overhead expense: Officers' salaries. Salaries of office employees. Salary of superintendent. Estimating and selling expense (car fare, railroad fare, entertaining, etc.). Stationery and sundries. Postage, telephone, telegrams. Depreciation of tools and furniture. Insurance on property, furniture, stock, etc. Liability and compensation insurance (if any). Interest on investment. Rent (if owner of building, taxes and depreciation). Heat and light. Repairs. Attorneys' fees. License fees (if any). Association dues. Miscellaneous. 4 THE ELECTRICAL CONTRACTOR This list may be said to include the items which almost every electrical contractor must include in figuring his overhead expense, but not necessarily all the items which he must include. Most contractors find it necessary to employ one or more automobiles in their business. If such is the case, the interest on the investment made for automobiles, the depreciation of the machines, the cost of garaging, the cost of operating and the cost of upkeep must be included in the overhead expense. Some con- tractors have other expenses, such as advertising, etc., that are properly considered as items in overhead ex- pense. Hence, the list given is not complete but merely suggestive of the items which enter into a contractor's overhead expense. METHOD OF COMPUTING AND APPLYING OVERHEAD EXPENSE AND PROFIT From the preceding paragraphs it can readily be seen that any estimate for work which does not include, in addition to an estimate of shop cost, an item for manu- facturer's expense is one that will result in a loss to the contractor. The writer has found it more convenient and logical to compute the manufacturer's or overhead expense as a percentage of the shop cost, instead of as a percentage of the selling price. An estimate of overhead expense should be made at least once or twice a year and the per- centage thus obtained added to the shop cost in all esti- mates made in the succeeding period to obtain the real cost. For example: Shop cost: Pay of foremen, journeymen, helpers and apprentices $80,000.00 Cost of material, engines, generators, conduit, wire, etc. . 200,000.00 Total shop cost $280,000. 00 PROFITS AND OVERHEAD EXPENSE 5 Overhead expense: Salaries of employers, co-partners or officers $30,000.00 Salaries of office employees bookkeepers, clerks, etc 8,000.00 Salaries of superintendent, draftsman and engineer 10,000.00 Stationery, telephones, taxes, insurance, rent, etc 8,000 . 00 Total manufacturer's expense $56,000.00 Manufacturer's or overhead expense as a percentage of shop cost equals $56,000 -T- $280,000, or 20 per cent. The real cost, therefore, of the year's business would be the shop cost, $280,000, plus the overhead expense of $56,000, or $336,000. Should the selling value of this work be $369,600, the contractor has made a profit of 10 per cent, on the investment made. Should the selling value, however, be only $334,992, he has lost 3 per cent, on his investment. A true estimate should, therefore, be made for any job as follows: Shop cost $10,000.00 Overhead expense at 20 per cent 2,000. 00 Real cost $12,000.00 Profit at 10 per cent 1,200 . 00 Amount of proposal. $13,200.00 Some contractors figure their overhead expense as a percentage of the selling price. If a contracotr's over- head expense is 20 per cent, of his selling price and he desires to make a profit of 10 per cent, on the selling price, he would not make it if he used the following method: Shop cost $1,500.00 20 per cent, overhead expense plus 10 per cent, profit 450 . 00 Amount of proposal $1,950 . 00 To get the results desired namely, 20 per cent, of selling price as overhead expense and 10 per cent, of 6 THE ELECTRICAL CONTRACTOR selling price as net profit the estimate should be made in the following manner: If the shop cost is $1,500, this amount must represent 70 per cent, of the selling price, for the overhead expense is taken as 20 per cent, of the selling price and the profit is taken as 10 per cent, of the selling price. Hence the selling price should be ($1,500 -r- 70) X 100, or $2,142. The overhead expense is 20 per cent, of $2,142, or $428, and the profit is 10 per cent, of $2,142, or $214. The sum of these two items, $642, subtracted from the selling price leaves the origi- nal shop cost of $1,500. Hence the previous method of estimating was in error by $2,142 - $1,950, or $192, as shown. But the entire principle of applying overhead expense and profit as percentages of the selling price is wrong. Profit on a job is actually interest on an investment. The investment in the contractor's business is the sum of the shop cost and the overhead expense. Hence the profit should be computed as a percentage of this sum. CHAPTER II BOOKKEEPING Different systems of bookkeeping are, of course, in use by electrical contractors. Some lack merit and others are of great usefulness. In designing any book- keeping system it should be borne in mind that the simpler the system can be made the more satisfactory and efficient it will prove to be, provided that it gives all the information that the contractor should have about his business, such as overhead expense, cost of labor and materials for each individual piece of work and the gross profit of the same. The system of bookkeeping to be described is the one employed by the firm with which the writer is connected. This system has been found very satisfactory and requires the minimum of labor. Upon the receipt of an order for performing a certain piece of work, an order card (Fig. 1) is filled out and turned over to the credit department, where the rating, financial responsibility, etc., of the prospective customer is examined. If the result of this inquiry is satisfactory, the card is passed to the bookkeeping department, where the information contained on the card is entered in the contract ledger and the card filed in the order- card index file. In the contract ledger, under the entry for the job, are charged all labor and material actually used on the job until the work is completed, no entry being made, how- ever, for office expense. 7 ELECTRICAL CONTRACTOR * c. . /"" "N Q r n D ff III tt ^> V. J c. _c i : d i/> ca 1 ' 3 a a a> E M 'i 1 Z r> E " E 1 ill A a cc * cT 2, s i Q. (A E M i 0> M 2 fi 111 J c 1 1 "2 | s s 1 J a> jQ | 1 1 U LJ 1 D = _ F c a 1 Q | JC i td I 2 i! c3 1 a 5 o U _ 1 Q 2 -SI -1 CD c- e a 1 c 5 D H si ? rH j -a | s "c . , d S D i: c5 a o a C j= J "c _ C 5 .2 Is a Z ra a ** r C. " "c to "C . g -S a "S3 o I 1 1 c u c S 1 1 i-e id .2 5 fe 5? |i * I - s 1? L a> c: -0 >% * E H- "5 E id Z o c c a E n Z i . Location BOOKKEEPING 9 After the plans and specifications for the work are received the engineering department lays out the work, straightens out any discrepancies between the plans and the specifications, and secures any other information which may be necessary for the construction depart- ment to know before proceeding with the actual work. The plans and specifications are then turned over to the construction department, the superintendent of which fills out a job card (Fig. 1) with the name of the man who has been selected to be foreman of the work. The card then becomes the foreman's order for the work and is kept by him until the completion of the job. When the card is returned, the bookkeeping department knows the job has been completed and is ready for billing. This process is repeated in the case of any ex- tra work which may be ordered by the customer, no foreman or workman being permitted to do any extra work on a contract until a job card for the same has been issued. When the construction department starts a piece of work the superintendent fills out a stock-requisition sheet (Fig. 2). To guide him in ordering materials a copy of the estimate showing the estimated amounts of materials needed is also given him. Upon the receipt of the material at the job a second list is filled out on a special receipt form and receipted by the man in charge. After a job is completed, the surplus material is again listed and returned to the stock room, where the stock clerk enters the amount of material received on another special receipt form. Sheets such as those described are also filled out by the foreman in charge when material is transferred from one job to another and does not pass through the stock room. 10 THE ELECTRICAL CONTRACTOR Note: -No material will be given Separate sheets must be n taken that no writing or it Materials can not always be but must be purchased. Thereto much ahead as possible of the d actually needed. In urgent case available make requisition by ph written sheet to confirm it. Try requisitions in at least as early ials are needed. Stockroom is o No. JOB NAME O PAl STOCK-REQUISITION SHEET Week Ending without a requisition neatly and completely filled out. lade out for each job or extra, and in making out requisitio larks be made in right hand column. sent from our stockroom, re make requisitions as ate when materials are 8 whern K telephone ia rpt nt* W JB us care .ed Sii must be [nature .aree. one, and send in the particularly to have all as the day before mater- >en at 7.30 a.m. KELLER-PIKE CO. KELLER-PIKE CO.Gentlemen:-Please send the following material for use on job of which I have c Ordered Amoun' Filled From Supply Amount Filled From Stock Amount Wanted DESCRIPTION OP Amount /alue from Stock Order No ARTICLES WANTED Brought Fwd. FIG. 2. Requisition sheet for construction materials. BOOKKEEPING 11 By referring to the stock-requisition sheet (Fig. 2), it will be noticed that the amount of material desired is placed in the fourth column from the left, the amount of that material supplied from the stock room in the next column, and in the adjoining two columns the amount of that material furnished by any local supply house, together with the initials of the supply house and the contractor's order number to the supply house. All material going to a job is, therefore, entered, but only that portion of the materials supplied from the stock room is valued on the sheet, the amount being credited to the stock room and charged to the job. The material furnished by the supply house is billed by the supply house, whose account in the main ledger is cred- ited and the amount charged in the contract ledger. The list of materials on the requisition sheets becomes, therefore, the bookkeeping department's " sheet of origi- nal entry," and these sheets are filed in an indexed loose- leaf ledger. The other material sheets mentioned are, on the other hand, simple memoranda for checking and receipts for materials. To charge the stock room and credit a job on the return of materials, or to credit one job and charge another where materials have been transferred without passing through the stock room, a sheet similar to the requisition form, but of different color, is filled out in the office from the data contained on the other types of material sheets mentioned. The bills for work done can be made out readily, the price being already established. In time-and-material work it is necessary for the billing clerk to refer to his contract ledger and copy down all material and labor items which have been charged to the work, giving the 12 THE ELECTRICAL CONTRACTOR DISTRIBtlTIO'N OF PAYROLL WEEK Els rnrvn 19 NAME OF JOB LABOR EXTRAS TOTAL _r \_ (^\ \J TTI V^ (~\ LJ TOTAL FIG. 3. Form of payroll (itemized). BOOKKEEPING 13 price at which the same were charged and noting whether the material was furnished from the stock room or from a supply house. This bill is made out in pencil and turned over to the construction department, by which it is examined and, if found correct, passed to the person pricing the material and labor. The distribution of the labor on various jobs is made by the pay-roll clerk on a pay-roll sheet (Fig. 3), and the various jobs are charged and the cash account cred- ited from this sheet. CHAPTER III COST-KEEPING In order to obtain figures on costs it is necessary for a contractor to employ such cost-keeping systems as will enable him to know the unit costs of performing the various operations entering into the execution of any wiring contract. Unless a contractor does employ such cost-keeping methods, he can hardly be said to be en- gaged in business, for he is merely playing a game of chance with his entire investment and business future at stake. In estimates for work there are two items of costs : 1. Costs of material. 2. Costs of labor. No accurate figures for use in estimating the cost of the materials used on a job can be given, owing to the constant changes in price of most of these materials, such as wire, conduit, etc. On the other hand, while the rates paid for labor change, the changes are not of frequent occurrence and tables of labor costs can be worked out on the present rates for labor and any in- crease or decrease of rates can be taken- care of by employing a percentage correction factor. For engines, generators, motors, transformers, etc., it is always best to secure a bid on the apparatus direct from the manufacturer, especially if a reasonable time be given the contractor to prepare his estimate. It is preferable to have these quotations include the cost of 14 COST-KEEPING 15 the apparatus delivered and erected in position, as well as the cost of foundations, templets, bolts, painting, etc. There are two reasons for this procedure: First, unless the percentage of profit is large, the contractor should not undertake the risk of accepting the apparatus f.o.b. point of delivery and taking the responsibility for any damage that may occur to the same before it is accepted by the owner. Second, the contractor is very likely to omit a number of items in estimating on such apparatus, and these items combined may amount to a considerable sum even though each is small itself, Should, however, the job be a large one and the time for preparing an estimate be short, the approximate cost of the apparatus could be determined if the con- tractor has prepared curves of cost for the various sizes of such apparatus in the past and had frequently checked them. Such checking is absolutely necessary, as apparatus may vary considerably in price within comparatively short periods of time. Fig. 4 shows how these curves should be prepared. Separate curves or tables should be prepared for directly connected and belted, single and four-valve or Corliss engines, also for directly connected and belted, direct-current and alternating-current generators of various types, as well as for motors of low, medium and high speeds, etc. The same method could be followed for figuring the cost of certain other kinds of materials, although greater accuracy must be used in plotting some curves, for in some cases price differences of a few cents may be de- sired. This method is not intended to be pushed to its logical conclusion and made to apply to such items as switches, outlet boxes, receptacles and the like, the 16 THE ELECTRICAL CONTRACTOR 4UU 4600 4400 4200 4000 3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600 / / / . 7 / / / *,/ / t^ 1 / y / y" <: / .p* *"/ / f ^ r y h ^< ^ / ^ / /' s ~? / if x X / y / x / / ' / x / V / / '/ , ^ ) 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 40 Sizes of Generators in K.V.A. FIG. 4. Curves showing the cost of directly connected engine-driven direct-current and alternating-current generators installed under ordi- nary conditions, the bases being furnished by engine contractor. COST-KEEPING 17 prices of which the contractor generally has at his finger tips, but it can be applied advantageously to such mate- rial as panel boxes, panelboards, doors and trim, an- nunciators, watchmen's clocks, etc. For checking purposes or naming approximate costs to an owner for work being done on a time-and-material basis, this method can be used with the labor and material costs, combined as the data for these costs can be secured in the contract ledger from the completed jobs. Take the following example, which is the cost for wiring a new residence of brick-and-joist construction b*y the concealed-conduit method. The service cables were run down the outside wall, the meter being in- stalled in the basement. The system was three-wire, 110-220-volt, single-phase. The panelboards were of slate with 30-amp. type B switches, mounted in iron boxes, with wooden doors and trim. The switches were of Cutter manufacture and the receptacle of the flush wall type and of Pringle manufacture. The wire was rubber-covered and of the National Electrical Code standard. The shop cost as shown by the contract ledger was $400.75, the cost items being as follows: Materials $254 . 36 Labor 136 . 74 Car fare, etc 9 . 65 Shop cost $400.75 The residence had 32 light outlets, 28 switch outlets and 20 receptacle outlets. The cost of a switch plus the labor of installing it was $1 and the cost of a recep- tacle plus the labor of installing it was $1.10. If all outlets were light outlets, the shop cost would 18 THE ELECTRICAL CONTRACTOR have been approximately $400.75 - [(28 X $1) + (20 X $1.10)] or $350.75. Dividing $350.75 by the total number of outlets, which is 80, $4.38 is obtained. Hence $4.38 is the cost of wiring per light outlet. The cost of wiring a switch outlet is $4.38 + $1, or $5.38, and the cost of wiring a receptacle outlet is $4.38 -f $1.10, or $5.48. This method is fairly accurate for small-residence work, and any number of costs per outlet may be com- piled to cover the various types of wiring construction, wiring systems, etc. Tables I to XI, 1 inclusive, give data from which such curves can be plotted, or, if desired, the data may be retained in tabular form. Too much emphasis, however, cannot be laid on the advisability of preparing such tables and curves from one's own records. 1 Figures in Tables I, II, III and V are the figures the electrical con- tractor would secure from his subcontractors. Tables IV, VI, VII, VIII, IX, X and XI include the contractor's overhead expense and profit. TABLE I. COST OF ENGINES AND THEIR FOUNDATIONS INSTALLED READY FOR STEAM-PIPE CONNECTIONS 1 Horsepower rating Single Tandem-compound Four-valve 50-100 100-200 300 and above $16.00 15.00 14.00 $26 . 00 24.00 $25.00 23.00 1 Installed ready for steam-pipe connections under ordinary condi- tions. The figures given are based on data from the Ames Iron Works, Oswego, N. Y. COST-KEEPING 19 TABLE II. COST OF DIRECTLY CONNECTED DIRECT-CURRENT AND ALTERNATING-CURRENT GENERATORS 1 Direct-current Alternating-current Rating, kw. Cost per kw. Rating, kva. Cost per kva. 25 $25.00 50 $16.00 35 23.00 75 14.00 50 20.00 125 13.00 75 16.00 135 12.00 100 15.00 185 10.00 125 14.00 250 9.00 150 13.00 312 9.00 200 12.00 350 8.00 250 12.00 375 and above 8.00 300 and above 12.00 1 These prices are based on engine-driven generators installed under ordinary conditions, the sub-bases for the erection of the generators being furnished by the engine contractor. The values given are based on data obtained from the General Electric Company. TABLE 111. COST OF SWITCHBOARDS, INCLUDING DYNAMO AND FEEDER PANELS, 220 VOLTS OR LESS 1 Direct-current Alternating-current Rating, kw. Cost per kw. Rating, kva. Cost per kva. 25- 50 50-100 100 and above $5.00-$10.00 4.00- 8.00 3.00- 6.00 50-125 125-350 350 and above $4.00-$6.00 3.00- 4.00 2.00- 3.00 1 The range of prices is due to variations in the grade of materials and workmanship, the number of instruments, switches, etc. These figures include the switchboards erected complete and ready for the connection of generator cables, power and light feeders, etc. The prices are based on data obtained from the Walker Electric Company, Philadelphia. 20 THE ELECTRICAL CONTRACTOR TABLE IV. COST OF DYNAMO CONNECTIONS' Direct-current Alternating-current Rating, kw. Lead-sheathed rubber insulation Rubber-covered cable in conduit Rating, kva. Lead-sheathed rubber insulation Rubber-covered cable in conduit 25- 50 50-100 100 and above $50.00-$ 150. 00 75.00- 250.00 100.00- 350.00 $25.00-$125.00 50.00- 225.00 75.00- 325.00 50-125 125-350 350 and above $100.00-$300.00 200.00- 400.00 300.00- 500.00 $75.00-8275.00 175.00- 375.00 275.00- 475.00 1 The average flat distance between dynamo and switchboard has been assumed as 25 ft. TABLE V. COSTS PER HORSEPOWER OF MOTORS AND NECESSARY RHEO- STATS AND CONTROLLERS ERECTED 1 Direct-current Alternating-current Horsepower Cost Horsepower Cost 1 3 $50 . 00 1 - IH $60.00 5 - 7H 40.00 IK- 2 50.00 7K- 10 30.00 2-3 40.00 10 - 15 25.00 3 - 7H 30.00 15 - 25 20.00 7^-10 25.00 25 - 50 18.00 10 -20 20.00 50 -100 15.00 20 -35 18.00 100 -250 13.00 35 -75 15.00 250 and above 12.00 100 and above 13.00 1 Motors are assumed to be of standard speeds, voltage, etc., and to be erected on floor, cost of foundations not being included. The costs include delivery and erection ready for wiring connections and are based on data obtained from the General Electric Company. COST-KEEPING 21 TABLE VI. COSTS OF WIRING AND CONNECTING MOTORS, INCLUDING ALL LABOR AND MATERIALS 1 Horsepower Porcelain Molding Conduit 1- 5 $7 . 50-$75 . 00 $10.00-$100.00 $15.00-1150.00 5-10 30.00-120.00 40.00- 170.00 60.00- 240.00 15-25 75.00-250.00 90.00- 300.00 150.00- 300.00 25-50 100.00-400.00 125.50- 500.00 200.00- 500.00 50 and over 150.00-500.00 200.00- 600.00 300.00- 600.00 1 The range of figures is due first to structural difficulties, second to the type of motor panel desired, third to the voltage, and fourth to the circuit distance. The lower figures represent the minimum structural difficul- ties, with fused switches in an iron box and with starting device mounted exposed on wall to side of motor, 220-volt service and 50-ft. to 100-ft. circuit distance. The higher figures represent the maximum structural difficulties, motor panels with circuit-breakers, 110-volt service and 150-ft. to 300-ft. circuit distance. The figures do not include the cost of motors, rheostats and regulators. TABLE VII. AVERAGE COSTS PER OUTLET FOR WIRING FOR LAMPS IN NEW BUILDINGS 1 Outlets Exposed porcelain Wood Metal conduit molding molding Light .... $4 . 00-S8 . 00 $5.00-$10.00 $8.00-$16.00 $7.00-$14.00 Switch. . . 1 5.00-10.00 6.00- 12.00 9.00- 18.00 8.00- 16.00 Wall receptacle 5.00-10.00 6.00- 12.00 9.00- 18.00 8.00- 16.00 Floor receptacle 7.00-14.00 8.00- 16.00 11.00- 22.00 10.00- 20.00 Fan 6.00-12.00 7.00- 14.00 10.00- 20.00 9.00- 18.00 Iron 9.00-18.00 10.00- 20.00 13.00- 26.00 12.00- 24.00 Electric heater 7.00-14.00 8.00- 16.00 11.00- 22.00 10.00- 20.00 Vacuum control switch 2 12.00-24.00 13.00- 26.00 16.00- 32.00 15.00- 30.00 1 For use where the total cost of the work is about $2,000. For residences the lower figures should be used. For public buildings, such as banks, office buildings, churches and the like, a figure midway be- tween the range of figures given should be used. Where best grade of material and workmanship is required the higher figures should be used. Prices do not include costs of fixtures or appliances, but do include switches and receptacles. For wiring old buildings where porcelain work and conduit work is concealed the figures given should at least be doubled. If porcelain or conduit work is to be installed exposed in either old or new buildings, the figures should be increased at least 25 per cent., the difference of cost depending upon the purpose for which the building is or was designed. 2 Includes automatic starter at motor. 22 THE ELECTRICAL CONTRACTOR TABLE VIII. AVERAGE COSTS FOR SIGNAL SYSTEMS RUN CONCEALED IN NEW BUILDINGS 1 Costs per outlet (connected Bell wiring as one outlet) Porcelain Conduit Per push-button and bell $6.00 4.00 $12.00 8.00 Per drop on annunciator 1 For work on old buildings the figures given above should be doubled- The cost of push-buttons, bells and annunciators is included. TABLE IX. AVERAGE COSTS OF PRIVATE TELEPHONES Porcelain Per desk telephone . Per wall telephone . $30-$50 25- 45 Conduit $40-$60 35- 55 TABLE X. AVERAGE COSTS OF PUBLIC TELEPHONES IN NEW BUILDINGS, CONCEALED WORK* Conduit Per outlet. . $5 . 00-$ 15 . 00 1 Cost of wires is not included since the electrical contractor very seldom does the wiring. The range of the figures is due to variations in the dis- tances between outlets. Instruments are assumed to be furnished and installed by the telephone company. TABLE XI. COST OF INSTALLING MISCELLANEOUS WoRK 1 Apparatus Porcelain Conduit Time clocks $30 00-$45 00 $35 . 00-$50 . 00 per clock Time stamps Fire alarms Watchmen's stations 65.00- 85.00 20.00- 30.00 25.00- 35.00 70 . 00- 90 . 00 per stamp 25 . 00-35 . 00 per alarm 30 . 00- 40 . 00 per station 1 The range of the figures given above is due to differences in the grades of workmanship and materials. For old buildings the figures given should be increased from 25 to 50 per cent. These figures include the cost of apparatus as well as the cost of all conductors, conduits and labor. COST-KEEPING 23 WEEK ENDING 1 LABOR >'CONDT. 1 LABOR 2"CONDT. LABOR ^C14. D.W O * 3 s LABOR OUTLET BOXES LABOR FIX.SUP'P. LABOR SW.BOXES LABOR SWS. LABOR PANEL BOXES LABOR PANEL B'D. LABOR DOOR & TRIM LABOR METER B'D. &SW. TOTAL LABOR y z c. 2 C. 14 D. %w. LT.B. F.S. SW.B sw. P.B.B P.B. D.&T M.B. . FIG. 5. Unit cost sheet compiled by clerk. 24 THE ELECTRICAL CONTRACTOR It is essential for the contractor to know the unit costs of labor for performing the various operations entering into the execution of any wiring contract as the method previously described will not give this information. The labor item in the electrical-contracting business is subject to changes due to variations in the price of labor resulting from increases or decreases of rates and to variations in the unit costs with the nature of the building construction. The latter variations may amount to 100 per cent, or more. The cost of labor can be determined with a fair degree of accuracy for buildings of various types, such as those of brick-and-joist construction, structural-steel construc- tion with terra-cotta or concrete floors, and reinforced- concrete construction, by the following method, which may be worked out as elaborately as necessary and made to cover not only the labor required for installing dif- ferent sizes of conduit, wires, etc., but also the labor required for connecting various sizes of wires to switch- boards, dynamos, lugs, etc. When a contract is secured in which the unit price of labor for certain parts of the work is not accurately known to the contractor, this information being desired for future use, he should endeavor to obtain these data by having a sheet such as shown in Fig. 5 prepared for his pay-roll clerk. A copy of this sheet should be given to the foreman on the job with instructions to mark his time sheets according to the symbols for the labor items as shown in Fig. 5, the time sheet thus marked being shown in Fig. 6. At the end of the week the pay-roll clerk inserts on his unit-cost sheet the amount of money expended dur- ing that week for the various labor items on the job COST-KEEPING 25 Pom 8-W-6J TIME I y-i- H 8. H. L _..___ Wf fi( f^ fling ,., M Notice Pay Roll close. Wednesdays. Time not then reported, will not be paid until the - following week. Hours:8 to 12 A.M. 12.30 to 4.SO P.M. KELLER-PIKE CO. Hour DESCRIPTION OF WORK EXPENSES 1 ^ 72." C ' 1 fy 2* C ff- >5//r &. 1 1 Tuesday ! /j * J? Total /(, -. Do Not Write la Sp*ce Below -8l Signature &&* Am*2^ /I Job Hw. <^xp. ^ si Total "~* MrtitAJLAtL*^ Unfits &0, Ik ET P . "~~~* FIG. 6. Time sheets showing symbols for labor items. 26 THE ELECTRICAL CONTRACTOR under way, the total of these items equaling the total pay-roll for that job. This process is carried on until the completion of the work, at which time the total labor for each item is ascertained. Dividing the total labor for installing a certain material by the total amount of the materials installed, as ascertained from the con- tract ledger, a unit price is obtained for installing that material. It is very often desirable, however, to know what the unit price of labor is at the end of each week, especially if the job is some distance from the contractor's office and is visited by his superintendent only once or twice during the progress of the work. This can be accom- plished by the use of material sheets (Fig. 7) issued to the foreman. Taking, for example, the report on con- duit work, the foreman fills out the lines marked A, B, C and D for the first week, after which only the lines A, B and C are filled out. The line A designates the job. The line D, which is filled out only when the first slip is issued, indicates the amount of conduit on the job at the time the foreman arrives, while the line 5, which is filled in by the fore- man every week, indicates the conduit received during that week. Now, the line C, which is filled out by the foreman every week, indicates the amount of conduit on hand at the end of the week. Hence, the sums of the amounts of materials entered on the lines B and D minus the amounts entered on C, that is, B -\- D C, for the first week indicate the amounts of the different sizes of conduit installed during that week. After the first week the sums of the amounts of con- duit along the line D of the first week's report and along the line B of all subsequent weekly reports, minus the COST-KEEPING 27 REPORT ON CONDUIT WORK THE FIRST WEEK THE FOREMAN WILL FILL OUT THE LINES A. B. C AND O. AFTER THAT THE LINES A. B ANO C ONLY. KELLER-PIKE CO. Z i e & .S 3 s o (H O d & a - REPORT ON WIRE WORK L FILL OUT THE LINES A. B. C AND D. AFTER THAT THE LINES A. B AND C ONLY. KELLER-PIKE CO. 1 2 i 5 i * REPORT ON OUTLET WORK THE FIRST WEEK THE FOREMAN WILL FILL Our THE LINES A. B. C. AND D. AFTER THAT THE LINES A. a ANO C ONLY. KELLER-PIKE CO. z ! i g o O 5 8 e j X y s ii .8' I o 3- JL ill o J t y a 1 Q e. 1 CD I $ i! I 1 5 Q 1 2 I! j S 9cS 1 n * O i ii Q m _ < i 1 I 5 i J o \\ III 1- I IP f j]| Q m 8 * iii s O ll - 28 THE ELECTRICAL CONTRACTOR amounts along the line C of the last report, indicate the amounts of the different sizes of conduit installed up to the time of the last report. The labor costs from the weekly time sheet (Fig. 6) are then inserted along the line marked ' 'labor cost," and the unit prices are accurately figured and placed along the line marked " price per unit." If the price per unit for any item is higher than the estimated price, the head of the construction department indicates this by placing a red cross opposite the particular item to which he desires to call the attention of the superin- tendent. The latter immediately investigates the mat- ter, reporting on any possible causes for the increased costs and on the possibility of reducing the unit price. This same process is carried out for wire work and outlet work. In the usual installation these items of conduit work, wire work and outlet work are by far the largest portion of the labor item, so that the work on signal systems, bells, etc., can be neglected. Otherwise the cost involved for ascertaining unit prices on the minor work would far overbalance the benefits of know- ing these particular labor costs. In Tables XII to XXIX as obtained by the above method are given the unit costs of labor. The data, however, cannot be considered general in their applica- tions, for conditions vary widely in the electrical con- tracting field. Every contractor should make his own tables and curves, utilizing his records for the purpose. In all the following tables it is assumed that the rates for labor are 55 cts. per hour for foremen, 45 cts. per hour for wiremen, and 25 cts. per hour for helpers. All figures given include an allowance for what has been COST-KEEPING 29 found to be necessary supervision by the foreman in the class of work under consideration. TABLE XII. COST PER KILOWATT FOR ERECTING BELTED GENERATORS Size in kw. Normal condition Easy Difficult Cost of painting 1 - 5 $1.00 $0.75 $1.50 $0.60 5 -12^ 1.00 0.75 1.50 0.60 12^-25 " 1.00 0.75 1.50 0.50 25 -50 1.00 0.75 1.50 0.40 75 0.80 0.60 1.25 0.30 100 0.75 0.60 1.20 0.25 150 0.60 0.50 0.90 0.20 200 0.50 0.40 0.80 0.18 300 0.40 0.30 0.60 0.15 500 30 20 50 12 TABLE XIII. COST PER KILOWATT OF FOUNDATIONS FOR BELTED GENERATORS 1 Size in kw. Normal condition Easy Difficult 1-5 $2.00 $1.50 $3.00-$4.00 5 -12K 2.50 2.00 3.75- 5.00 12^-25 2.00 1.50 3.00- 4.00 25 -50 1.50 1.00 2.25- 3.25 75 1.20 0.85 1.80- 2.80 100 1.00 0.75 1.50- 2.50 150 0.85 0.60 1.25- 2.25 200 0.75 0.60 1.00- 2.00 300 0.60 0.50 0.90- 1.80 500 0.50 0.40 0.75- 1.50 1 The items under this heading include the cost of labor and materials, which is the usual method of estimating this class of work. The figures are based on the average cubical contents of foundations specified by generator makers. If the electrical contractor is to furnish the belt or belts, the labor for putting them in place should be included. 30 THE ELECTRICAL CONTRACTOR TABLE XIV. LABOR FOR ERECTING SWITCHBOARD PANELS Dynamo panel without sub-base Dynamo panel with sub-base Feeder panel without sub-base Feeder panel with sub-base Cost per panel $10.00 $12.00 $12.00 $15.00 TABLE XV. LABOR PER LEAD FOR CONNECTING SWITCHBOARD AND DYNAMO LEADS 1 Size, B. & S. Paper and lead Rubber and lead Rubber or slow-burning insulation 14-8 $0.33 $0.30 $0.21 6 0.45 0.41 0.28 5 0.55 0.50 0.33 4 0.66 0.60 0.40 3 0.80 0.72 0.49 2 0.87 0.79 0.53 1 0.92 0.84 0.56 1.00 0.90 0.60 00 1.04 0.94 0.63 000 1.08 0.98 0.65 0000 1.14 1.03 0.69 Circ. mils 250,000 1.18 1.08 0.72 300,000-350,000 1.34 1.22 0.78 400,000-450,000 1.43 1.30 0.84 500,000-550,000 1.60 1.44 0.90 600,000-650,000 2.10 1.90 1.00 700,000-750,000 2.50 2.25 1.25 800,000-850,000 2.95 2.65 1.50 900,000-950,000 3.30 3.00 1.75 1,000,000 3.75 3.40 2.00 1 These figures are the labor costs for soldering cables into lugs at the switchboard and generators, also for soldering light and power cables into lugs of switches on the switchboard. They include the cost of arranging the cables in a neat and workmanlike manner at these locations. COST-KEEPING 31 TABLE XVI. LABOR COSTS (IN CENTS) PER FOOT OF CONDUIT WORK [ Size of conduit Steel-terra-cotta construction Concrete construction Slow-burning construction Exposed Concealed Exposed Concealed Exposed Concealed Small am't Large am't Small am't Large am't Small am't Large am't Small am't Large am't Small am't Large am't Small am't Large am't \ effective lumens per lamp where S = the number of square feet floor area of the room and 7 = the required average intensity of illumi- nation required in foot-candles. The term " effective lumens per lamp" refers to the total light flux from lamps that is available for illumination purposes. To illustrate this method the following examples may be cited. A storeroom to be lighted measures 40 ft. by 100 ft. Considering the goods to be sold, it is decided, 72 THE ELECTRICAL CONTRACTOR after referring to the table of foot-candle intensities recommended for various classes of service (Table XXXIX), that 3 ft.-candles is sufficient for general illumination. Then the total lumens of light flux re- quired would be three times the area in square feet, or 40 X 100 X 3, which is equal to 12,000 lumens. By turning to Table XL of effective lumens for tungsten- filament lamps it is found that under ordinary conditions the number of 25-watt, type B lamps necessary would be 12,000 -5- 120, or 100. With 40-watt lamps 12,000 -T- 200, or 60, would be required. These calculations are subject to correction for color of the wall and ceilings, types of reflectors used, etc. For example, if clear holophane reflectors are to be used in the store referred to above, and the walls and ceiling are of medium tint, the effective lumens from the lamps may be considered as 10 per cent, greater. If opaque reflectors were used instead of clear glass, the increase in illumination resulting from light ceilings and walls would be negligible, while if certain kinds of opal glass shades were used the influence of color of the ceiling and walls would be greater. It is somewhat difficult to estimate the difference in resulting illumination with different color decorations, and in residence work, where the wall paper may be changed from time to time, it is not wise to rely too much on reflection from surfaces. For lighting by the use of indirect-lighting fixtures the writer has found the flux-of-light method to be very satisfactory when based on 0.4 watt per foot- candle for each square foot of horizontal surface to be illuminated. To find the proper type of reflectors to be used curves like those shown in Fig. 15 may be employed. To find ILLUMINATION CALCULATIONS 73 the proper shade to be used, knowing the height of the unit above the floor level and the spacing between units, follow the vertical line representing the spacing between s OC / / /^ / / / / / / 32 / / / / // / f / ' S 28 t> A / o y / / ? 7 J/ / ^3 / / 1 $/ / / ^ x^ I" // // ,,^ / ^ ^ bd C -.0 / / / y ^ ^ f.p lo C / / & ' C& ^ ^ 1 / / / f > ^ 19 / A / ^ JX 10 / , / / x V / / / / s ^ A // / ^ ^ 246 10 12 14 16 18 20 22 24 26 28 30 32 34 Spacing Between Outlets in Feet 40 42 FIG. 15. Curves for selecting type of reflector. units until it intercepts the horizontal line marked "mounting height,' 7 and use the shade which is shown by the diagonal line to be nearest the point thus located. CHAPTER VIII GENERAL DATA Such data as have been found necessary for the esti- mating and laying out of both large and small interior and underground electrical installation is included in this chapter. Data such as can usually be obtained from tables in the National Electric Code and from manu- facturers' literature are, in general, omitted. INTEKIOR CONSTRUCTION Conduit, Elbows and Couplings. Dimensions referring to this material are omitted as the same can be obtained in the conduit manufacturers' catalogues. Wire. The diameters, weights and resistances for different sizes of wire can likewise be obtained in the wire manufacturers' catalogues. TABLE XLI. OUTSIDE DIAMETERS OF BUSHINGS AND LOCKNUTS Size, in. Outside diameter of bushings, in. Outside diameter of locknuts, in. Thickness of bushings, in. Thickness of locknuts, in. H 1 1H Ke H H 1K6 IKe % >^ i Ifc w H ^2 IK 1% 2Ke He Ke 1H 2H 2^6 KG 2 2^ 3>^ % %6 2y 2 3^ 3% M KG 3 4 4% % KG 3>i 4Ke 5M 1 KG 4 5 5% 1 KG 74 GENERAL DATA 75 Locknuts and Bushings. It is usually necessary to know the outside diameter of locknuts and bushings the diameters of which establish the spacing distances of conduits entering junction boxes, etc. Panelboards. The approximate sizes of panelboards are included as such sizes very often determine their location. TABLE .XLII. APPROXIMATE SIZES OF PANELBOARDS 1 Number of circuits Two-wire mains, two-wire branches, dimensions, inches Three-wire mains, two- wire branches, dimensions, inches, 110 volts 110 volts 220 volts 2 5.75 X 12 7 X 12 5.75 X 13.5 4 8.00 X 12 10 X 12 8.00 X 13.5 6 10.25 X 12 14 X 12 10.25 X 13.5 8 12.50 X 12 17 X 12 12.50 X 13.5 10 14.75 X 12 21 X 12 14.75 X 13.5 12 17.00 X 12 24 X 12 17.00 X 13.5 14 19.25 X 12 27 X 12 19.25 X 13.5 16 21.50 X 12 30 X 12 21.50 X 13.5 18 23.75. X 12 34 X 12 23.75 X 13.5 20 26.00 X 12 37 X 12 26.00 X 13.5 22 28.25 X 12 40 X 12 28.25 X 13.5 24 20.50 X 12 43 X 12 30.50 X 13.5 26 32.75 X 12 47 X 12 32.75 X 13.5 28 35.00 X 12 50 X 12 35.00 X 13.5 30 37.25 X 12 53 X 12 37.25 X 13.5 1 For panels where N.E.C. inclosed fuses of 30 amp. and under are employed. No switches are assumed to be used on branch buses, and the main buses are assumed to be without switches or fuses. 76 THE ELECTRICAL CONTRACTOR TABLE XLIII. APPROXIMATE SIZES OF PANELBOARDS, DIMENSIONS IN INCHES 1 Number of circuits Two-wire mains, two-wire branches Three-wire mains, two- wire branches, 110 volts 110 volts 220 volts 2 7 X 22 7 X 22 7 X 22 4 11 X 22 11 X 22 11 X 22 6 15 X 22 15 X 22 15 X 22 8 17 X 22 ' 20 X 22 17 X22 10 20 X 22 23 X 22 20 X 22 12 23 X 22 27 X 23 23 X 22 14 27 X 23 32 X 23 27 X 23 16 29 X 23 35 X 23 29 X 23 18 32 X 23 39 X 23 32 X 23 20 35 X 23 44 X 24 35 X 23 22 39 X 23 48 X 24 39 X 23 24 41 X 24 52 X 24 41 X 24 26 44 X 24 56 X 24 44 X 24 28 48 X 24 60 X 24 48 X 24 30 52 X 24 64 X 24 52 X 24 1 For panels where fuses and switches of 30 amp. and under are em- ployed for branches and where no fuses or switches are provided on the main buses. Knife Switches. TABLE XLIV. AVERAGE OVERALL DIMENSIONS OF N.E.C. FUSED AND FUSELESS SWITCHES, FRONT-CONNECTED l Size Double-pole, inches Three-pole, inches Four-pole, inches Five-pole, inches Fuseless switches. H. W. D. H. W. D. H. W. D. H. W. D. 30 11 7 291s 11 10 29fe 11 12 29i6 11 15 29ie 60 13 8 2% 13 11 2% 13 14 2% 13 17 2^ 100 15 9 3H 15 12 3K 15 15 3}4 15 19 3H 200 19 10 4^6 19 13 4$i6 19 17 4*1 6 19 21 4*A6 Fused switches. . . H. W. D. H. W. D. H. W. D. H. W. D. 30 11 7 2iMe 11 10 2i?l6 11 12 2i?ie 11 15 2iMa 60 13 8 3?6 13 11 3H 13 14 3H 13 17 3H 100 17 9 4ft 17 12 4ft 17 15 4# 17 19 4H 200 21 10 5 21 13 5 21 17 5 21 21 5 Data furnished by the Walker Electric Company, Philadelphia. GENERAL DATA 77 From the above table the sizes of iron boxes for knife switches may be obtained. General. Such data as the carrying capacity of wires, the number of wires in a single conduit, the sizes of such conduits and so forth can be found in Rules 18 and 28, 1915 National Electrical Code, as issued by the National Board of Fire Underwriters. UNDERGROUND CONSTRUCTION Excavation. The average contractor sublets this por- tion of his work, the cost of which will average between 50 cts. and $2 per cubic yard depending upon the soil. Concreting. What has been said regarding excava- tion applies to this item likewise, the cost of which will average between $9 and $15 per cubic yard. For con- tractors' estimates on their own concrete work the fol- lowing table giving the various amounts of concrete, sand and stone per cubic yard of rammed concrete in different proportions, will be found useful. TABLE XLV. AMOUNTS OF CEMENT, SAND AND STONE REQUIRED PER CUBIC YARD OF RAMMED CONCRETE Stone, mixtures 1 in. and under Screened-out amounts Concrete Sand Stone Concrete, bbls. Sand, cu. yd. Stone, cu. yd. 1 2.0 4 1.46 0.44 0.89 1 2.5 5 1.19 0.46 0.91 1 3.0 5 1.11 0.51 0.85 1 3.0 6 1.01 0.46 0.92 1 3.0 7 0.91 0.42 0.97 1 4.0 7 0.83 0.51 0.99 1 4.0 8 0.77 0.47 0.93 Brick Work in Manholes. What has been said regard- ing the above items applies to this item likewise, the 78 THE ELECTRICAL CONTRACTOR cost of which will average between 75 cts. and $1.50 per cubic foot. Vitrified Ducts. TABLE XLVI. OUTSIDE DIMENSIONS OF VITRIFIED DUCTS Type Bore, round or square, in. Outside dimensions, in. Single-way 3U 5 X 5 X 18 Two-way Three-way Four-way 3^ 3^ 3U 4 X 9 X 24 5 X 13 X 24 9 X 9 X 24 Six-way 3U 9 X 13 X 36 Nine-way Nine-way 3>i 2 13 X 13 X 36 9 X 9 X 36 Telephone Cables, The usual literature of wire manu- factures does not give the outside diameters of paper- covered lead-encased telephone cables. The following table applies to type G lead-covered telephone cables as manufactured by the Western Electric Company. TABLE XL VII No. of pairs Outside diameter, in. No. of pairs Outside diameter, in. 5 H 40 2 %2 10 KG 50 % 15 X 60 7 A 20 %6 75 15 /16 25 % 100 IKe 30 5 /8 120 1^2 35 ll Ae 150 1%2 200 1% Electric Light and Power Cables. The usual literature of wire manufactures does not give the outside diameters of rubber-covered, lead-encased cables. GENERAL DATA 79 Single Conductor. TABLE XL VIII. OUTSIDE DIAMETERS OF CABLES FOR 600 VOLTS PRESSURE OR LESS Size Thickness of rubber, in. Thickness of lead, in. Outside diameter Solid, in. Stranded, in. 14 %4 %4 0.28 0.30 12 %4 %4 0.30 0.31 10 %4 %4 0.33 0.34 8 %4 %4 0.35 0.38 6 KG KG 0.47 0.47 5 KG KG 0.50 0.50 4 KG KG 0.52 0.52 3 KG KG 0.53 0.55 2 KG KG 0.56 0.58 1 %4 KG 0.63 0.66 %4 KG 0.69 00 %4 KG 0.73 000 %4 KG 0.78 0000 %4 KG 0.84 250 M 3 /32 %4 0.95 300 M 3 /32 %4 1.02 350 M 3 /B2 %4 1.08 400 M 3 /32 %4 1.11 450 M 3 /32 ^4 1.19 500 M 3/ 32 %4 1.20 550 M %4 %2 1.33 600 M %4 %2 1.34 650 M %4 3 /32 1.38 700 M %4 %2 1.41 750 M %4 %2 1.44 800 M %4 %2 1.47 850 M %4 %2 1.50 900 M %4 % 1.53 950 M / D 4- %4 Xo Z %2 1.56 1000 M %4 %2 1.59 80 THE ELECTRICAL CONTRACTOR Duplex Conductor. TABLE XLIX. OUTSIDE DIAMETERS OF CABLES FOR 600 VOLTS PRESSURE OR LESS Size Thickness of rubber, in. Thickness of lead, in. Outside diameter, stranded, in. 14 %4 H4 0.30 X 0.50 12 X* H4 0.31 X 0.53 10 H4 H* 0.34 X 0.59 8 %4 KG 0.41 X 0.69 6 KG KG 0.47 X 0.81 5 KG KG 0.50 X 0.88 4 KG KG 0.52 X 0.91 3 KG KG 0'.55 X0.97 2 KG H4 0.61 X 1.06 1 W4 H4 0.69 X 1.22 H4 %4 0.72 X 1.28 00 4 H4 0.77 X 1-.38 000 H4 %4 0.81 X 1.47 0000 H4 ^4 0.88X1.59 250 M %i Ha 0.95 X 1.64 300 M 3 /32 Hi 1.02 X 1.88 350 M 3 /32 Ha 1.08 X 2.00 400 M 3 /32 %2 1.11 X 2.06 450 M 3 /32 .H2 1.19 X 2.22 500 M 3 /32 H? 1 . 20 X 2 . 24 Triplex Conductor. Size Thickness of rubber, in. Thickness of lead, in. Outside diameter stranded, in. 14 H4 KG 0.59 12 %4 KG 0.63 10 %4 KG 0.70 8 %4 KG 0.77 6 Ke %4 0.94 5 KG ^4 1.00 4 KG ^4 1.03 3 KG %4, 1.09 2 KG Hi 1.13 1 %4 */32 1.19 %4 H 2 1.28 00 %4 H 2 1.38 000 %4 %2 1.50 0000 %4 H2 1.64 INDEX AMPERES PER H. P. FOR A.-C. MOTORS 57 ANNUNCIATOR SYSTEMS, COST OF. ..." 22 B BELL SYSTEMS, COST OF 22 Bookkeeping 7-13 Bills and billing 9, 11, 13 Contract ledger 7, 11, 17, 26 Main ledger 11 Pay-roll distribution 12, 13 Order cards for jobs 7, 8 Order cards for workman 8, 9 Requisition sheet 9-11 Transferring materials on jobs 9,11 BUSHINGS, DIMENSIONS OF 74 Cables. Cost of connecting at dynamo and switchboard 30 Cost of pulling and splicing 39, 40 Dimension of single-conductor electric 79 Dimension of double-conductor electric 80 Dimension of three-conductor electric 80 Dimension of telephone 78 Candle Power. Curves of 64, 65 Definition of 62, 63 Concreting. Cost of 77 Various proportions used in 77 Conduit. Cost of laying rigid 38 Cost of running rigid 31 Cost of running flexible 31 Construction Department. Method of checking weekly costs 26-28 81 82 INDEX Requisition sheets 9,10 Special receipt sheets 9,11 Stockroom 9,11,13 Sup't 9,26,28 Time sheet 25 Workman's order card 8, 9 Costs 14-40 Curves of 15-17 Items of 14 Method for obtaining approximate 15-18 Method for obtaining unit 23-29 Pay-roll clerk's sheet of unit 23 Tables of approximate 18-22 Tables of unit 29-40 Time sheet lor ascertaining unit 25 Weekly sheets of unit 26, 27 CROSS-ARMS, COST OF ERECTING 37 CURVES, METHOD OF PREPARING 15-17 D Ducts. Cost of laying 38 Dimension of 78 DOUBLE NEUTRAL MAINS 49 Dynomas. Cost of 19 Cost of connecting cables 20, 30 Cost of erecting belted 29 Cost of foundations for belted 29 E ENGINEERING DEFT., WORK OF 9 ENGINES, COST OF 18 Estimates 41-45 Detail of branches 42 Detail of mains 43 Interior construction 41-42 Logical arrangement 41, 42, 44, 45 Overhead construction 44, 45 Underground construction 44 EXCAVATING, COST OF 77 Expenses (Manufacture or Overhead} 1-6 Items of 3, 4 Meaning and nature of 2, 3 INDEX 83 Method of applying 5, 6 Method of computing 4, 5 National electrical contractors association, data of 3 FAN OUTLET, COST OF INSTALLING 21 FIRE ALARM SYSTEMS, COST OF INSTALLING 22 FIXTURE SUPPORTS, COST OF INSTALLING 34 FOOT CANDLES, DEFINITION OF 63 FOOT CANDLES, TABLE OF 71 FLUX OF LIGHT METHOD 70-72 G GLOBES, ABSORPTION OF LIGHT BY 69 H HEATER OUTLET, COST OF INSTALLING 21 HENRY'S METHOD OF CALCULATING 58, 59 Illumination 62-73 Absorption of light by globes 69 Calculating size of units 68-71 Candle-power, definition of 62, 63 Candle-power, curves 64, 65 Desirable size of squares for spacing 69 Effect of reflection from walls 67, 68 Foot-candles 63, 71 Flux of light method 70-72 Indirect lighting-watts per foot-candle 72 Intensity of illumination 63-66, 71 Lumens, definition of 70 Lumens, table of effective 71 Reflectors 72, 73 IMPEDANCE 59 INDUCTANCE 53-59 IRON OUTLET, COST OF INSTALLING 21 J JOBS, TRANSFERRING MATERIALS ON 9, 11 84 INDEX K Knob-and-tube Work. Cost per foot for concealed 35 Cost per foot for exposed 36 L LABOR, VARIATIONS IN COST OF 24, 28 LIGHT OUTLETS, COST OP INSTALLING 21 LOCKNUTS, DIMENSION OP 74 LOSSES A.-C. circuits 53-61 LOSSES D.-C. circuits 46-52 LOSSES at contacts 50 LUMEN, DEFINITION OF 70 LUMEN, TABLE OF EFFECTIVE 71 M MANHOLES, COST OF . 77, 78 MOLDING WORK, COST OF 36 Motors. Cost of 20 Cost of installing and connecting 33 Cost of installing and connecting control apparatus .... 34 Cost of wiring and connecting 21 Current consumption of A.-C 57 MULTIPLYING FACTORS FOR A.-C. CIRCUITS 56 O OHM'S LAW 47 ORDER CARDS JOB 7, 8 ORDER CARDS WORKMAN 8, 9, 10 OUTLETS, COST OF WIRING VARIOUS 21, 22 Outlet Boxes. Cost of installing light 34 Cost of installing switch 34 Cost of installing receptacle (floor) 34 Cost of installing receptacle (wall) 34 P Panel Boards. Cost of installing 33 Dimension of .' 75,[76 PAY-ROLL, DISTRIBUTION SHEET FOR INDEX 85 POLE LINE CONSTRUCTION 44, 45 Poles 37 Cost of digging holes for 37 Cost of erecting (iron) 37 Cost of erecting (wood) 37 Cost of erecting cross-arms on 37 Cost of guying 37 Cost of shaving 37 Cost of stepping 37 Profit 1-6 Meaning and nature of 1,2,5,6 Method of applying 5, 6 National Electrical Contractors Association, data of .... 3 Power-factor. Definition of 53, 54 Table of averages 54 R REACTANCE 58, 59 RECEIPTS SPECIAL 9, 11 Receptacles. Cost of installing and connecting 33 Cost of installing boxes for 34 Cost per outlet for floor 21 Cost per outlet for wall 21 REFLECTORS, CURVES OP PROPER 72, 73 REQUISITION SHEETS 9, 10 Resistance. Method of approximating 48 Of 1/0 wire 48 Of a circuit carrying a given current 51 S SELF-INDUCTION 58 SHOP OR REAL COST 2 SIGNAL SYSTEMS, COST OF 22 SKIN EFFECT 53 STOCK ROOM 11 Switches (Push button). Cost per outlet 21 Cost of installing and connecting 33 Cost of installing boxes for 34 SWITCHES (KNIFE), DIMENSION OF 76 86 INDEX Switchboards. Cost of 19 Cost of connecting cables at 20, 30 Cost of erecting 30 T TELEPHONE SYSTEMS, COST OF 22 THREE-WIRE BALANCE SYSTEM 48, 49 TIME CLOCK SYSTEMS, COST OF 22 TIME SHEETS 25 TIME STAMP SYSTEMS, COST OF 22 U UNDERGROUND CONSTRUCTION 44 V VACUUM CONTROL OUTLETS, COST OF 21 VOLTAGE LOSSES ON A.-C. CIRCUITS 53-61 VOLTAGE LOSSES oisi D.-C. CIRCUITS 46-52 W WATCHMAN'S CLOCK SYSTEMS, COST OF 22 Wire. Calculating sizes for A.-C. circuit 53-61 Calculating sizes for D.-C. circuit 46-52 Cost per ft. fishing conduits and pulling 32 Cost per ft. stringing 38 Method of approximating resistance of 48 Multiplying factor for A.-C. circuits 56 Relative sizes of for D.-C. and A.-C. . 55 t 3380 153 Engineering Library - UNIVERSITY OF CALIFORNIA LIBRARY