a. This British Standard specifies requirements for 'Efglas'* type cables for aircraft wiring of circuits in which the potential between conductors, or between a conductor and metal braid or the aircraft structure, does not exceed 600 volts (r.m.s.) and the frequency does not exceed 1600 c/s and where any combination of ambient tem-perature and conductor current for continuous service does not produce a stabilized conductor temperature in excess of 260℃. The cables remain flexible at temperatures down to -70℃.The cables do not support combustion but do not comply with the requirements of British Standard 2G. 100 in respect of fire resistance.
b. The generic name 'Efglas' is applicable only to cables covered by this British Standard and complying with all its requirements.
c. The standard includes the following ranges of cables:
(i) Efglas. Cable with a copper conductor and com-posite insulation of glass and polytetrafluoroethylene (PTFE).
*The various combinations of the word 'Efglas' used to distinguish these cables were originated by the Royal Aircraft Establishment of the Ministry of Aviation.
(ii) Efglasmet. Similar to the Efglas range but with the addition of a metal braid.
(iii) Efglasmetsheath. Similar to the Efglasmet range but with the addition of an external sheath of PTFE and glass braid.
(iv) Efglaslarge. Similar to the Efglas range but with a greater thickness of insulation and with a correspondingly greater resistance to abrasion. These cables have the same overall diameters as those specified for the equivalent American cables (in U.S. Specification MIL-W-7139), but are heavier than their Efglas counterparts.
(v) Duefglas and Triefglas. Two- or three-core cables consisting of two or three Efglas cables marked with coloured stripes for phase identification and twisted
together.
(vi) Duefglasmetsheath and Triefglasmetsheath. Duef-glas and Triefglas cable assemblies with an overall metal braid and with a PTFE sheath over the braid.
d. The cables are classified and identified, not by current ratings, but by a series of numbers indicative of the conductor cross-sectional area. These numbers correspond to those used for equivalent American cables.
An indication of the relationship between this system of identification and that provided by British Standard E.21, Electric cables for aircraft (Pren Type), is given in Appendix A for information.
A guide to the current ratings of Efglas cables is given in Appendix B.
BS G 192:1965 history
1965BS G 192:1965 Specification for Efglas type electric cables with copper conductors for aircraft