April 1, 1911.] 



THE INDIA RUBBER WORLD 



239 



NEW INSULATED WIRE SPECIFICATIONS. 



THE revised electrical rules of the l-.lcctrical Department 

 of the city of New York were promulgated during March 

 and take etTect April 1. These new rules arc mucli more dras- 

 tic in regard to the tests applied to insulated wire than were 

 the old ones. 



Rule No. 41 provides that all tests shall apply on all wire 

 at the time of manufacture as well as up to and including the 

 time of installation. This rule is intended to provide against 

 deterioration between the time of manufacture and installation. 

 The rule also provides that the insulation must consist of 

 rubber or other approved compounds homogeneous in char- 

 acter, adhering to the conductor. The thickness of the in- 

 sulation for each size wire is definitely specified in the rule. 



Tests for the hardness of the insulation provide that, after 

 the braid has been removed, the insulation must be sufficiently 

 elastic to permit all wires smaller than No. 7, to be wrapped 

 five times around a cylinder of specified size (Nos. 8, 9 and 

 10 double the diameter of the wire measured over the insulation. 

 No. 11 and smaller equal to tiie diameter of the wire) without 

 injuring the insulation. 



The tests for softness of insulation provides that the in- 

 sulation must present sufficient resistance to crushing or tension 

 to withstand the following to tests : 



Test A. — A sample of wire of sufficient length for test, about 20 

 inches, shall have the braid and insulation removed for about two 

 inches at each end, leaving the braid and insulation on balance of 

 sample. One end of the bare copper shall be fastened to a clamp on 

 a shaft, and a ten-pound weight attached to the other bare copper end 

 of the wire. The shaft shall then be revolved ten times in ten seconds, 

 wrapping the sample in a close, even wind around the shaft. With the 

 tension left on the sample, it shall then be immersed in water at a 

 temperature of 60 degrees Fahrenheit for 34 hours, immediately after 

 which time it shall, while still immersed, be subjected to 1,500 volts 

 alternating current for one minute and shall show an insulation resist- 

 ance equal to at least half that required by the test formerly provided 

 at 100 volts. 



Test B. — Sample to be tested shall have braid carefully removed for 

 at least one inch from one end. The wire itself shall be connected to 

 one terminal of an electric circuit, of which a testing tool shall be 

 the otiier terminal. This circuit shall have a potential of at least 100 

 volts alternating, or 140 volts direct current and a resistance of at 

 least 1,000 ohms. 



The portion of the wire with braid removed shall be placed on a flat 

 surface and subjected to a pressure, vertically applied by means of the 

 edged tool, of five pounds for fifteen minutes. The tool edge shall 

 be sharp and the sides of the edge shall form an angle of 90 degrees 

 with each other. During this period the tool edge, when placed trans- 

 versely to the insulation shall not sink through sufficiently to touch the 

 copper wire and complete the electric circuit. 



All of the above insulations must be protected by a substantial 

 braided covering, properly saturated with a preservative compound. 

 This covering must be sufficiently strong lo withstand all the abrasions 

 likely to be met with in practice, and must substantially conform to 

 approved samples by the manufacturer. 



Manufacturers of rubber covered wires are particularly 

 pleased with these new rules and predict that tlie efi'ect of ihem 

 will be to keep off the market inferior materials in which the 

 insulation contains little rubber. 



The City Electrician of Chicago has notified tin- Imilders and 

 contractors of that city after April 1. No electrical work in 

 which rubber covered wire is used will be approved in that city 

 unless the insulation conforms to the revised specifications of 

 the Electrical Department of New York City, as quoted above. 



At the biennial meeting of the National Board of Fire Under- 

 writers, which was held in New York March 22 and 23, changes 

 in the specifications and rules governing rubber-covered wire 

 were adopted. The board practically adopted the report of the 

 electrical committee and all of the changes made were in the 

 direction of making more drastic the regulations and more severe 

 the tests required. For the most part the new rules of the under- 

 writers will be identical with those, referred to above, which 

 have been adopted by the New York Department. The tests and 



requirements as to material and construction are practically the 

 same. The tables for the thickness of insulation on the various 

 sizes of wire are the same. 

 The rule for testing the insulation reads : 



Any one foot sample of completed covering must show a dielectric 

 strength sufticient to resist throughout five minutes the application of 

 an electro motive force proportionate lo the thickness of insulation 

 (according to a definite table specified in the rule). • • * The applica- 

 tion of the electro motive force shall first be made at 3,000 volts (alter- 

 nating current) for five minutes, then the voltage increased by steps of 

 not over 3,000 volts, each held for five minutes, until the rupture of the 

 insulation occurs. The test for dielectric strength shall be made on a 

 sample wire which has been immersed in water for seventy-two hours. 

 One foot of the wire under test is to be immersed in a conducting liquid 

 held in a metal trough, one of the transformer terminals being connected 

 to the copper of the wire and the other to the metal of the trough. 



The rules provide that every length of completed wire or cable 

 must be tested after not less than twelve hours immersion, and 

 while still immersed, by the application for one minute of an 

 alternating current of a voltage graded according to the size of 

 the wire (as provided in the tables). Any length of completed 

 wire may be tested after 30 days' immersion, and must show not 

 less than SO per. cent, of the insulation resistance required after 

 twelve hours' immersion. The results of the insulation tests at 

 different temperatures are to be reduced to a basis of 60 degrees 

 F. by using standard multipliers which are provided in the rules. 



The tests for softness and for elasticity are practically the 

 same as those referred to above as having been adopted by the 

 New York Department. 



A new rule has been added to the series of tests, which reads as 

 follows : 



41. J. — Five chemical tests shall be made of the rubber compound as 

 follows: Acetone extract, alcoholic potash extract, chloroform extract ash 

 and total sulphur. The sum total of the results of these five tests shall 

 not exceed 80 per cent, by weight of the total compound — tests to be 

 made according to Underwriters' Laboratories Specifications. 



The ash test shall be supplemented by tests to deternnne the quality 

 of substances, other than vulcanized rubber, which are combustible, but 

 not soluble in acetone, alcoholic potash or chloroform, and any such 

 substances shall be counted as ash. 



These ne\y rules will probably be promulgated in April, but 



will not go into effect for five or si.x months in order to give 



manufacturers an opportunity to dispose of their present stocks. 



LABELS FOR DRUGGISTS' SUNDRIES. 



THE drug and surgical department of The B. F. Goodrich Co. 

 (Akron, Ohio) has adopted a uniform style of label to be 

 used in future. This is a design effect with stippled border at 

 the bottom to show the Goodrich name and address, with a heavy 



INFANT 

 BULB SYRINGE 



No. 173 



Color: WHITE 



Style: PLAIN 



THE B.F. GOODRICH COMPAMV 



^'t.KR-OW RUBBEK. V>fORKS — AKK.0N.0H10.V.S.>^. 



The GodiiRicH Uniform Druggists' Sundries Label. 



line border at top and sides. .Xmple space is provided for featur- 

 ing the particular goods involved. The general color scheme will 

 be lettering m black on a white background, although some ex- 

 ceptions will probably be made. The size and shape of label will 

 necessarily vary lo conform to the different styles and sizes of 

 boxes employed, but in each case the general design effect will 

 be maintained. The object for wliich they are striving is to 

 provide a means of ready identification of Goodrich goods to the 

 buyer at large. It is not known that this idea has ever been 

 followed out before in so complete a manner, and doubtless it 

 will be regarded with considerable interest in the trade. 



"Rubber Tires and .K\\ .\bout 'I'licm"— a book for everybody 

 who has to do with tires. 



