1. This British Standard specifies the requirements for 'Pren' type cables for aircraft wiring of circuits where the potential between conductors, or between a conductor and metal braid or the aircraft structure docs not exceed 600 volts (r.m.s.) in voltage and 1600 c/s in frequency; also where any combination of ambient temperature and conductor current for continuous service does not pro-duce a stabilized conductor temperature in excess of 90℃. These cables arc suitable for fixed wiring in aircraft when low temperatures (……75℃) arc encountered, but are not suitable for severe flexing below ……40℃.
The cables do not support combustion but they should not be regarded as complying with the requirements of British Standard G.100, General requirements for electrical equipment and indicating instruments for aircraft in regard to fire resistance.
The cables are unsuitable for use without additional protection in areas where ester-based fluids are present.
The generic name 'Pren' shall be applied only to cables covered by this British Standard and complying with all requirements of the specification.
The standard includes the following four ranges of cables, the complete nomenclature of which is given in Appendix A:—.
a. Pren. Cable with a copper conductor and an insulation of glass braid and polychioroprene com-
pound, for single core cables: multi-core cables have an overall finish of glass braid and lacquer: the conductor of the Uniflexpren cable is of a braided construction which shall not be on a string centre.
b. Prenal. Similar to the Pren range but with a conductor of aluminium instead of copper.
c. Prenmet. Similar to the Pren range but with the addition of a metal braid.
d. Prensheath. Multi-core Pren cables sheathed with a polychioroprene compound in place of the lacquered glass braid.