in a manner to permit a measure of relative movement between a conductor and the material of the insulation coating and thereby provides an increase in capability of flex and flex life of the conductors of the core the flexibility and flex life of the core may be optimized by cabling the conductors together in a unidirectional manner with a length of lay illustrated by an angle u03c6 the angle may be between 25 u00b0 to 35 u00b0 in a cable having ten 10 conductors and an outer diameter of about one inch the length of the lay may be about ten inches the length of the lay may be determined by some multiple of the outer diameter thus a cable having ten 10 conductors and an outer diameter of one and one half inch may have a length of lay of about fifteen inches the preferred angle u03c6 may be about 30 u00b0 a binder thread 22 is wrapped about the core the binder thread serves the function of maintaining the conductors in their cabled condition and thus the integrity of the core during the period prior to application of jacket 14 the binder thread may be a cotton thread once the jacket is applied over the core the binder thread is no longer required thus it matters not whether the binder thread should deteriorate or otherwise break the drawing see fig1 illustrates the binder thread in a widely spaced spiral wrap the.