550 



THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1953 



wrapping tension in Fig. 31. Another method of removing a connection 

 is by unwinding the helix. This may be done by using a pair of pliers 

 as shown in Fig. 32. Either end of the wire may be used for unwrapping. 

 A terminal is not seriously damaged by stripping off a wrapped wire, 

 however, the re-use of the stripped off wire is not recommended. A wire 

 may be reconnected by skinning to the proper length and wrapping. 

 When the wire is not sufficiently long to provide the necessary number 

 of turns to insure a good connection, one or two turns may be wrapped 

 and then soldered. 



CONNECTION OF LARGE AND SMALL WIRES 



There is no upper limit to the size of wire wrapped on adequately 

 proportioned terminals. Connections have been made with both alu- 

 minum and copper wire over 200 mils in diameter with satisfactory re- 

 sults. The torque necessary to wrap large wire is considerable, since it 

 increases with the third power of the diameter. A 20-mil wire requires a 

 winding torque of 100 inch grams whereas, a 200-mil wire requires 

 100,000 inch grams (18 foot pounds). Wires as small as No. 39 (0.0035'' 

 dia.) may also be wrapped, however, the design of the wrapping tool 

 must be changed slightly in order to facihtate the loading of the fine 

 wire into the tool. 



DIMENSIONAL RELATIONS 



The data given in this paper refer only to No. 24 copper wire 20 mils 

 in diameter. The terminal width ♦most frequently used in conjunction 

 with this size wire is about one-sixteenth inch or three times the wire 

 diameter. The terminal width may also be twice the wire diameter or 

 slightly less, however, the one-sixteenth inch size has been chosen for 



APPLIED WRAPPING TENSION, AF »• 



Fig. 31 — Stripping force in terms 

 of applied wrapping tension. 



Fig. 32 — Unwinding wrapped con- 

 nection with pliers. 



