Could you be an electrician in 1912?

Could you be an electrician in 1912? Check your knowledge - Wiring & lighting questions

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Questions On The Subject Of Electric Wiring

  1. Explain the three-wire system of wiring.

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

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

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

  2. Compare the advantages of the two-wire and three-wire systems of wiring.

  1. Under what general heads are approved methods of wiring classified?

  2. 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.)

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

  2. 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.)

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

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

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

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

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

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

  1. How far apart should insulators be placed?

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

  1. What regulations govern the use of fibrous tubing?

  2. What is meant by mutual induction?

  1. What are the advantages and disadvantages of overhead linework as compared with underground linework?

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

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

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

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

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

  1. 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?

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

  1. 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.

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

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

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

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

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

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

  1. 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%.

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

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

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

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

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

  1. Describe the Bunsen Photometer.

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

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

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

  1. How are arc lamps rated?

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

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

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

  1. What is meant by flashing? Explain.

  2. Define emissivity.

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

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

  1. Compare the open and enclosed arc lamps.

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

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

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

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

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

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

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

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

  2. Name the advantages of the Nernst lamp.

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

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

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

NT

Reply to
NT
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They had metal conduit? When I bought my first house in the mid 70's it still had "live" gas pipes in the wall from the original gas lighting, although it had been modernised presumably around 1912. The lighting wires ran in surface mounted E channel wood sections with a pinned-on cover, each channel carried a single conductor, rubber insulated and cotton covered. At least the power circuits, such as they were, were mostly PVC (some lead/rubber).

Reply to
newshound

harry wibbled on Tuesday 27 July 2010 20:28

Snip dude, snip ;->

Yes, very interesting.

Apart from the funky lamps, the odd weird term, it read "more modern" that I would have expected. Didn't feel to me that it was written a full century ago.

At least they weren't getting in a tizzy about bonding the coal shovel and stuff :)

Reply to
Tim Watts

No baths to bond in those days!

I am going to cheat and look in my 1931 Electrical Educator book for some of the answers:-)

Adam

Reply to
ARWadsworth

NT gurgled happily, sounding much like they were saying:

The first one on a hot day.

Reply to
Adrian

My parents house was wired in more modern times, 1950. The mains cable was pinned to the walls and sheathed in lead. Be worth a fortune today!

Reply to
Broadback

I still keep coming across disused bits of lead sheathed cable in the loft of our 1930's bungalow. Surprisingly the insulation looks to be in remarkable condition where it's been exposed at the cut ends - not that I'd suggest that it would still be safe to use. A "junction box" for the lead sheathed cable I came across looked quite scary though - a thin piece of metal sheet with 4 cable clamps equally spaced round the edge and a porcelain terminal block in the middle, it didn't look as if it ever had any sort of cover.

Reply to
Mike Clarke

In article , Tim Watts scribeth thus

Presume the Two wire and Three wire are single and three phase systems not just Two core and T&E ?...

Reply to
tony sayer

Single phase and 2 phase, fwiw.

NT

Reply to
NT

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Interesting that all the questions require written answers. Not a multiple-choice in sight.

Reply to
Andrew May

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>>>>

It predates GCSE by a decade or six.

Reply to
dennis

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no multiple choice? You had to actually answer the questions? ;-)

Reply to
Graham.

We've still got a lot of cloth-covered/rubber stuff in our place (built

1949) - they replaced the accessible bits (e.g. most of the ground floor due to access available via basement) but the lighting and top floor is still mostly the old crap.

There's even evidence of knob-and-tube wiring in some of the outlying buildings, although it's long since been replaced with more modern stuff.

cheers

Jules

Reply to
Jules Richardson

There's another electrician's questionnaire from an 1899 book on the same site, if anyone's really determined. It didnt look so enlightening though.

NT

Reply to
NT

In article , Andrew May writes

And no one seems to have noticed that it's American in origin.

Reply to
Mike Tomlinson

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