Numerous illustrative examples are worked out in detail in the foregoing sections of this Cyclopedia - in order to show the application of the various methods and principles. Accompanying these are examples for practice which will aid the reader in fixing the principles in mind.

In the following pages are given a large number of test questions and problems which afford a valuable means of testing the reader's knowledge of the subjects treated. They will be found excellent practice for those preparing for College, Civil Service, or Engineer's License. In some cases numerical answers are given as a further aid in this work.

## Review Questions On The Subject Of Electric Wiring

1. Explain the three-wire system of wiring.

2. In case a test shows excessive leakage, or a ground or short circuit, how would you locate the trouble and remedy it?

3. Describe the construction and use of outlet-boxes.

4. What is the principal difference between alternating and direct-current circuits, so far as concerns the wiring system?

5. Compare the advantages of the two-wire and three-wire systems of wiring. 6. Under what general heads are approved methods of wiring classified?

7. A single-phase induction motor is to be supplied with 25 amperes at 220volts; alternations 12,000 per minute; power factor .8.

The transformer is 200 feel from the motor, the line consisting of No. 4 wire, 9 inches between centers of conductors. The transformer reduces in the ratio 2,500/ 250, has a capacity of 30 amperes at 220 volts, and, when delivering this current and voltage, has a resistance-E.

M. F. of 2.5 per cent, and a reactance E. M. F. of 5 per cent. Calculate the crop. (Use table and chart.)

8. What are the distinctive features of the different kinds of metal conduit?

9. Suppose power to be delivered, 300 K. W.; E. M. F. to be delivered, 2,200 volts; distance of transmission, 15,000 feet; size of wire, No. 00; distance between wires, 24 inches; power factor of load, .7; frequency, 100 cycles per second. Calculate line loss and crop in per cent of E, M. F. delivered. (Use table and chart.)

10. In installing A. C. circuits, what requirements are insisted on as to the placing of conductors in conduits?

11. Describe the manufacture, use, and special advantages of the different kinds of armored cable.

12. Describe three different methods of testing? Which is to be preferred?

13. What conditions determine whether a two-wire or three-wire system of wiring should be used?

14. In locating cut-out cabinets and distributing centers, what requirements should be fulfilled?

15. What is "knob and tube" wiring? Explain its use and discuss its advantages or disadvantages.

16. How far apart should insulators be placed?

17. What tests should be made before an electric wiring equipment is finally passed for acceptance? Give reasons.

18. What regulations govern the use of fibrous tubing?

19. What is meant by mutual induction?

21. Describe and illustrate by sketches proper methods of supporting and protecting conductors.

22. Discuss the advantages of running conductors exposed on insulators.

23. Illustrate by diagram, proper and improper methods of grouping conductors of two two-wire circuits.

24. What dangers are inherent in the use of moulding? What precautions should be taken to avoid them?

25. Describe the proper methods of laying out branch circuits, (a) in fireproof buildings; (b) in wooden frame buildings. Give sketches.

26. What methods of installing wiring are best adapted for the following classes of buildings, (a) fireproof structures; (b) mills, factories, etc.; (c) finished buildings; (d) wooden frame buildings?

27. What is skin effect? Its bearing on the problem of wiring?

28. In selecting runways for mains and feeders, what precautions should be taken?

## Review Questions On The Subject Of Electric Lighting

1. State the current, voltage, candle-power, and efficiency of the incandescent lamp most commonly used.

2. What do you understand by the "smashing pint"?

3. Give the main points of difference between the three forms of arc lamp mechanism.

4. Mention the three principal parts of the Nernst lamp.

5. Describe with sketch the anti-parallel system of feeding.

6. Prove the law that illumination varies inversely with the square of the distance.

7. Why is arc light photometry a more difficult .problem than incandescent?

8. Calculate the illumination three feet above the floor at the center of a room 18 feet square and 12 feet high, lighted by four 10-candle-power lamps 9 feet above the floor at the center of the side walls, assuming the coefficient of reflection to be 50%.

9. What material is used for the filament of incandescent lamps? Explain why.

10. From the curve given in Fig. 4, determine the efficiency which corresponds to the temperature of 1300o Centigrade.

11. What is the object of double carbons in an arc lamp?

12. What is meant by mean spherical candle-power?

13. What is the function of the heater in the Nernst lamp?

14. Describe the Bunsen Photometer.

15. How does the lighting of public halls differ from that of residences?

16. Why cannot platinum wire be used for the filament of incandescent lamps?&9632;

17. In a direct-current arc lamp, which carbon burns away the more rapidly?

18. How are arc lamps rated?

19. What are the important advantages of the two-wire parallel system of distribution?

20. Name and describe the most desirable standard for photometric measurements.

21. How many measurements should be taken in the determination of spherical intensity?

22. What is meant by flashing? Explain.

23. Define emissivity.

24. If the voltage of an incandescent lamp be increased 4% above normal, what is the effect on the candle-power, efficiency and light?

25. Explain the Cooper-Hewitt lamp, stating the two methods of starting.

26. Compare the open and enclosed arc lamps.

27. Why is the positive carbon placed above the negative in a direct-current arc lamp?

28. Sketch and name the different forms of incandescent lamp filaments.

29. Under what conditions can a 3.1-watt incandescent lamp be used ?

30. What is the function of the arc lamp mechanism?

31. What are the advantages of the three-wire system?

32. Why is it necessary to exhaust the bulb of an incandescent lamp?

33. At what point in their life should incandescent lamps be replaced ?

34. What is the object of a resistance in series with the arc lamp in constant-potential direct-current systems?

35. Name the advantages of the Nernst lamp.

3G. What sort of lamps and of what candle-power should be used in residence lighting?

37. Give the characteristics of the Cooper-Hewitt lamp.

38. What will be the external resistance on a 110 volt constant-potential system, if the load consists of 437 lamps of 16 candle-power?

## Review Questions On The Subject Of Electric Lighting

1. Describe the proper method of pacing, nailing, and joining wood lath.

2. Of what materials is mortar composed? What are the requirements of each to insure good results?

3. Compare the relative advantages of metal and wood lathing for both interior and exterior plastering.

4. How are estimates for lathing and plastering made?

5. What precautions are absolutely necessary in the placing of metal lath?

6. If wood lathing is used on exterior work, how should it be laid?

7. When, if ever, is wire lath preferable to expanded metal?

8. Describe in detail the process of slaking the lime and mixing the mortar for ordinary interior plaster work in dwelling-houses. What precautions are to be observed ?

9. Should mortar be used as soon as mixed? Discuss this question in all its bearings.

10. 1How would you mix mortar for exterior work?

11. If lime is not thoroughly slaked, what trouble is likely to develop?

l2. What will be the effect of using too much lime in mixing mortar? too much sand?

13. What are the essentials for durable exterior plastering?

14. Discuss the relative advantages of three-coat and two-coat work. In what kind of work are three coats always necessary?

15. In interior work, what precaution must be observed in laying the successive coats of plaster? In exterior work?