The Moving picture world (January 1926-February 1926)

276 MOVING PICTURE WORLD January 16, 1926 Bluehook School Answers 421-426 (NOTE — There has been a mix-up of numbers in the Bluebook series of questions. Through a typographical error lists of questions appearing in December 5 issue and in December 12 issue both bear Nos. 422 to 426 inclusive, so that there are two 422, 423, 424, 425 and 426 questions.) Question No. 421 — What may happen if you cut straight through the insulation when stripping wire? Brother Budge busts the Christmas calm with this answer : Well, if you do that you are likely to amputate some of the small strands, if it be a standard wire, such as, for instance, asbestos covered, also you may 'nick' the wire, or cut a ring in its surface, which probably will cause the wire to break at that point If it be bent. Moreover, and also, should the wire be "alive"— which it should not be, of course, but we all do foolish things at times — and your body be grounded, you may get a peach of a jolt — just the current saying to you: "Pull that switch, you boob, before you begin taking my clothes off." fE Question No. 422 — Before connecting a wire to the terminal binding post of a switch, or other device, what should be done? E. G. Steele, Salt Lake City, Utah; C. H. Hanover, Burlington, Iowa; someone whose name is not on the answer sheet ; G. W. Bennewitz, Sioux Falls, South Dakota; G. L. Doe, Chicago, Illinois; Everett A. Fuller, Schenectady, New York; Allan R. Gengenbeck, New Orleans, Louisiana ; T. R. Guimond, Mobile, Alabama, and S. T. Anderson, St. Paul, Minnesota, all have made fair to excellent answers to this one. Gengenbeck says : In making connection to a iswitch "or other" binding post includes two very different conditions, since the "other" connection may be to a rheostat or an arc lamp, where the connection would be subjected to a more or less high degree of heat. In answering as to cold connections, I would say that considerable depends upon conditions. First, of course, the insulation is removed from the conductor for a sufficient distance, and no more, to permit of the operation which follows. The uncovered stub of wire should be thoroughly cleaned, either by scraping or with sandpaper — in practice usually by scraping. The terminal binding post to which the connection is to be made must be thoroughly clean, Insofar as has to do with its electrical contact surface. In theory a terminal lug should then be soldered to the wire end, the process of soldering being well described on page 121 of the Bluebook. In practice, however, this is not always either practical or especially desirable. I would put it this way: where the wire is a large one, solder a lug to it without fall, the lug to, of course, be attached to the binding post. It the wire be a small one, this Is neither necessary, or in many cases, such as incandescent lamp sockets, desirable or even possible. Just what the dividing line ought to be I don't know, but would suppose anything larger than a No. 10 wire should have a terminal lug. One reason for this is that large wires presumably carry heavy current, and the wire being round, when it is clamped under a binding post nut the actual contact between the round wire and flat metal surface of the nut and the binding post surface underneath is relatively small. With the smaller wire I bielieve it is proportionately considerably larger. In such matters my own procedure is to apply common sense and judgment. I think any man who ought to be allowed to make electrical connections at all should be able to tell when a lug is necessary and when it is not. As to hot binding posts, I hold that a lug should always be used, for the reason that the heat the connection is subjected to will corrode the connection very rapidly, and the ^IllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllltllllU^ j Bluehook School | g Queestion No. 440 — What is meant g I by a T. P. S. T. and a T. P. D. T. switch | 1 and where etre such switches used in p g projection practice? a I Question No. 441— What is a D. P. | 1 D. T. switch, and in what places might g 1 we have use for them in projection i 1 practice ? 1 1 Question No. 442 — What marks must 1 1 be stamped on some part of every s 1 knife switch ? 1 g Question No. 443 — May a knife 1 § switch be used for a higher or lower 1 1 amperage or voltage than it is marked = I for? I g Question No. 444 — In inspecting your 1 s switches each week, what faults would m. g you look for, and DO you make a 1 1 weekly inspection — or any periodic in 1 1 spection at all? | pKHiiiiiii iciiiiiiiiiaiuiiHiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiin lug sets up a condition which will resist deterioration through corrosion much better than will the other sort of connection. The lug must of course be of the compression type, since the heat makes solder impracticable. A most excellent, common sense discussion of the subject, it seems to me. Brother Gengenbeck, but to throw a monkey wrench into its wheels, I will quote friend Hanover's reply. He is right ! So, I personally believe, are you. Where men are involved who have the ability to apply common sense, I hold set rules usually should always be tempered with that commodity. The danger lies in men who have not the real ability to form safe judgment attempting to temper set rules with common sense. That is the thing which kills many people in automobile traffic of today. The capable, level headed man or woman can do many things which badly fracture the set rules and do them with entire safety. The trouble is that so many who are not capable or level headed try the same thing and — trouble is apt to follow. Hanover says : Follow the Electrical Code rules and you will be safe. That is absolutely correct, but Brother Hanover, doubtless thinking I knew the Code Rules by heart, said no more. Well, 1 don't, and unfortunately have not a copy of the Code by me. Just discovered that mine is gone. Probably loaned it to some one. Mad — spell it backward. Question No. 423 — What attention should termined binding posts of switches, rheostats, etc., have, and why is this attention of importance ? Doe says : They should be examined at periodic, set intervals, and kept clean as to their electrical contact. Once a month, say on the first, all connections should be examined carefully. To the average man it may seem a waste of labor to loosen and examine a connection which is apparently in good condition, but it is labor darned well wasted, just the same. It requires half an hour in the forenoon of the first day of each month for me to examine all electrical connections in my projection room, loosening them and making certain that the metal is clean and bright. It is labor well expended, and is no hardship to me. Rheostat and lamphouse connections should be examined every two weeks, assuming that they are used several hours each day. If only used for an evening show, then once a month will do, provided the connections be well made in the first place. Very good, friend Doe. I hold your "rules" to be good ones, and worthy of adoption in all projection rooms. Question No. 424 — Will power wasted in poor connections, burned wires, etcetera, be registered on the meter, and have to be paid for? Name the possible sources of waste of this sort. Bennewitz says: Power wasted in poor connections, burned wires, etc., will be registered on the meter and will have to be paid for as current consumed. The possible sources of waste of this sort are: House main feeders or branch circuits working over the rated capacity of the wires. Burned wires, loose wire splices, wire splices not soldered. Switches or fuse blocks working over rated capacity. Loose, dirty, corroded, or burned switch blades or contacts, Loose, dirty, corroded or burned fuse contacts. Terminal lugs loose on wire, dirty, corroded, or not making good contact with thing to which it is connected. Old rheostats which have had many heated arguments. Dirty, corroded, or burned rheostat control arm or contacts. Dirty, corroded, or burned carbon jaws. Dirty or rough motor, or generator commutator. Motor or generator brushes making poor contact with commutator. Grounded circuit. Which, I think, covers the ground very well, though the answer might be put into this form, as to possible sources of waste : Inefficient projectionist or machine operator who either don't know how to keep his equipment in shape or is too demmad lazy to do it. Question No. 425 — What do Underwriters' Rules require as to the making of wire splices ? Bennewitz answers thus : "Underwriters' rules require that wires must be so spliced, or joined that the bond will be mechanically strong and electrically perfect without solder. All joints except those made by some approved soldering device, must be soldered and all splices must be covered with insulation equal to that of the conductor itself." With which every one, in substance, agrees, so I think he must prob'ly be right. Question No. 426— Describe the proper method of making a wire splice, beginning with stripping the insulation. Bennewitz again makes a most excellent answer, as follows : In making a wire splice, we start by stripping the insulation from the ends of the wire to be spliced. The proper method of doing this is to cut into the insulation two or three inches from the end of the wire, making a tapering cut towards the end of the wire, and not cutting straight in, as some do. After the insulation is removed, scrape the wire until it is perfectly clean and bright. Then place the ends together so that one faces your right and the other your left. Adjust them to the desired length of splice you want, then grasp the two wires (to one side ot the center) with a pair of pliers and twist the free end of wire around the other wire. Not in a spiral direction, but so that each lap is snug against the preceding one, using another pair of pliers to twist it snug against the wire. After twisting one wire end, twist the other and solder the splice. Wrap with approved rubber tape, and then with approved friction tape to a thickness equivalent to that of the conductor. On page 122 of the Bluebook, fig. 26 shows different methods of making wire splices. Brother Fuller, the new "student," Schenectady, New York, also made an excellent answer, his remarks about acid in soldering flu.x, etc., having distinct value. The correct method of making wire splices