The Moving picture world (November 1925-December 1925)

498 MOVING PICTURE WORLD Bluehook School Answers No. 392 to 396 December 5, 1925 Question No. 392 — How should exit light* be fused? C. H. Hanover, Burlington, Iowa; S. F. Cooley, ^Manchester, New Hampshire; Annal R. Gengenbeck, New Orleans, Louisiana; W. C. Budge, Springfield Gardens, Long Island; G. W. Bennewitz, Sioux Falls, South Dakota ; F. H. Moore, Taunton, Massachusetts ; Rodney C. Clark, Lincoln, Lincoln, Maine ; G. L. Doe, Chicago, Illinois, and T. R. Guimond, Mobile, Alabama, all came through on this one, but for the most part only after a fashion. There was quite a bit of toestubbing, though most of the boys apparently had the right idea, but wer* shy on important details. Guimond says : If exit lights, as individual lights be meant, then each lamp should be separately fused, to the end that trouble in one of them will not affect the other lamps, but merely blow its own fuse. These individual lamp fuses should preferably be located at the beginning of the individual circuit which carries that one individual lamp, so that all other exit lamp circuits will be protected from trouble, not only in the individual lamp, but also in the circuit of each individual lamp. The fuse should be not to exceed one ampere in capacity. If exit lights in general are meant, then that point was covered in question No. 391, answers to which have already been sent in. An excellent and very complete answer, Brother Guimond, and one. which the rest will do well to observe closely, because this is a very important matter indeed. If trouble in one individual lamp, or lamp circuit, could cause the blowing of the main emergency circuit fuses, or the fuses of a circuit carrying a number of emergency lights, and that thing occurred just as the audience in a darkened theatre was on the verge of panic — not at all an impossible thing if individual light circuits be not separately and closely fused — you can see what a terrible situation might be set up. Bennewitz suggests a small automobile fuse block as excellent for single lamp fusing— makes a neat job. Question No. 393 — Describe an acceptable method of double fusing projector arc circuits, and tell us why it should be done. Just who is your b**t**ge*. Brother Moore, huh? Take my advice and get another I Your answer to this one starts off : All exit lights should be fused — etc and so forth and so on unto the end. We'll all give y' the horse laugh and — forgive you this time, but — change him I His stuff seems to be "not so good." Budge, Clark, Hanover, Guimond, Cooley, Bennewitz and Gengenbeck did very well on this one. Bennewitz says: The accepted method for double Xusing a projector arc circuit is to use a double pose, double throw switch which carries fuse contacts of approved type at either end. When the fuse at one end "lets go" it then Is only necessary to throw the switch blades over into the other position, in order to bring a fresh set of fuses into use. Of course if there is serious trouble, such as a short in the lamp, the other fuses will also be blown immediately, but since this proves that the trouble is serious, and the show must be stopped, whereas it is always possible that the fuse "blew" because of overloading through amperage boost because of a dark scene, or because of some fminor trouble such as poor mechanical fuse contact, it is well worth the wasted fuse to be certain, since stopping the show is a very serious matter. , < In this arrangement the wires froin the source of current supply are of course connected to the central switch contacts, and the outer contacts on one side of the switch are both connected to the positive lamp lead and the others to the negative lamp lead. The reason for double fusing has been Indicated in my reply. When a projection circuit fuse blows, it is not necessarily proof that there is trouble which would justify shutting down the projector on which possibly a large portion of a feature or other reel was still unprojected. The cause may be any one of several things, at least one of which may be inherent in that set of fuses themselves. The projector should only be shut down and the other started it the new fuses blow at once. That of course being proof positive that serious trouble amounting to a short exits somewhere in the circuit? Question No. 394 — What circuits may we fuse twentyfive per cent over and -above the capacity of the apparatus attached thereto? PREDDEY SUPER REFLECTOR LAMP Massive Construction Largest and Heaviest Lamp on the Market. Enclosed perfect automatic arc feed. Has pilot light. All outside adjustments. Takes 12" carbons. Double doors, double walled. heavy feed screw. No delicate parts. Fits a machines. $300 Walter Preddey 187 Golden Gate Ave, San Francisco, Cal. Hanover, Gengenbeck, Budge and Clark all agree that motor circuits may be fused 25 per cent above capacity of apparatus attached thereto, which is correct as far as it goes. Bennewitz, Cooley, Doe and Guimond agree that motor and projection arc circuits may be fused twenty-five per cent above the capacity of the apparatus attached thereto, which is entirely correct. Question No. 395 — On which side of the projection room mun switch should the projection room main fuses be placed, and why? Brother Bennewitz lands on us all spraddled out, as follows : It makes no great difference on which side of the projection room switch the projection room main fuses are placed, but the projector arc circuit feeders should be connected ahead of the main switch, and should have its own switch and fuse block. The argument as set forth on page 342 of the Blue Book is that it is more convenient to install fuses if the fuse block is "dead" than if it be "alive." Suppose, though, that we blow a fuse with the switchboard hook-up as shown on page 340 of the Blue Book. Are we to kill all the other circuits supplied by the main switch, just to have it convenient to install a new fuse? Not so you could notice it. so what difference does it make which side of the fuse is on the switch. Well, Brother Bennewitz, your argument is good so far as it goes, since certainly we would NOT kill the circuits on the other side in order to install a fuse on the dead side. The advice given in the Blue Book should have been to the effect that the reasons given only apply where a 2-wire circuit feeds the projection room. G'wan to the top of the class, darn y', but anyhow I'll crawl out through a knot hole by saying that the fuses are just as well on the "dead" side, and then when you wish to examine their contacts, as you should once a week anyhow, it is as well to have it so you can open the switch and by so doing have electrically dead fuses to handle, instead of live ones. Huh I Thought y' had me cornered, didn't ya? Well, y' got fooled. But even so, now that I've sat down on and properly squelched South Dakota (maybe), I'll say there is considerable merit in his separately-fused projection and incandescent feeders. It is very seldom indeed that the main fuses would be blown by any thing in the shape of a projection room incandescent circuit, and there is no use plunging the entire room into darkness because a projection circuit does it. Question 396 — It is very necessary that all fuses be in good condition. How would you construct a simple, reliable fuse tester? This is, in effect, a duplication of question 390. -Apologies. The answers are very short this week, true, but it will give us a bit of a, chance to catch up on other matter. iiiiiiiiii<iiiHiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii!iiiiiiitiiiiijiiiiiii.iin:iiiniHM^ ; I Richardson's I Handbook on I Projection 1 The euide to perfect projection. 1 Price, $6.00 postpaid. I Chalmers Publishing Company I 516 Fifth Avenue, New York City illlllllllllllllllllHIIIIIUIIIIIIIIIIIIIIIIIIIIIIUIIIIIIIl IllllllUIIIIIIIIIIIIIIIIIIIIIUIIIIIUIIIIIIlill :IMIiMIJ!.l»l