[Electric engineering.] . Fig. 49. 99. Cut-Out Switches.—The rules of the Fire Under-writers require that wherever constant-current arc wires 86 ELECTRIC LIGHTING. 18 enter a building, an approved double-contact service switchshall be installed, so that the current may be cut off at anytime. These switches must be substantially made, must bemounted on incombustible bases, and must be placed wherethey may be easily reached by policemen and are many different types of these cut-out switches,but they should all have good contacts and be quick inaction. The switch must also show clea
[Electric engineering.] . Fig. 49. 99. Cut-Out Switches.—The rules of the Fire Under-writers require that wherever constant-current arc wires 86 ELECTRIC LIGHTING. 18 enter a building, an approved double-contact service switchshall be installed, so that the current may be cut off at anytime. These switches must be substantially made, must bemounted on incombustible bases, and must be placed wherethey may be easily reached by policemen and are many different types of these cut-out switches,but they should all have good contacts and be quick inaction. The switch must also show clearly whether the cur-rent is on or off. Fig. 50 shows the working parts of the Wood arc cut-out, astyle that has been extensively used and which will serve to. fig. so. Fig. 51. illustrate the operation of cut-out switches in general. Theparts here shown are mounted in a waterproof cast-iron boxwith an opening past which an indicator moves to showwhen the current is on or off. Fig. 51 shows the external appearance of the blades a, b, Fig. 50, are attached to the line termi-nals c, d, as shown. The house terminals are connected tothe posts e, f. When the handle is pushed up, the porce-lain rollers r, r press the blades into the clips on termi-nals e, f and thus connect the line with the lamps. Whenthe lever is pulled down, the rollers bear on the lower part ofthe blades, causing them to leave the clips on the posts e, fand swing over so as to rest on the casting k, thus cutting § 18 ELECTRIC LIGHTING. 87 out the lamps and allowing the current to flow directlyacross from one blade to the other and disconnecting thehouse wires entirely from the line. The springs shown inthe figure make the action quick and positive. 100. Cut-Outs on
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