This SAE Recommended Practice covers the wiring and rectangularly shaped connector standards for all types of trailers whose gross weight does not exceed 10 000 lb (4540 kg). These trailers are grouped in SAE classes 1 through 4 as delineated in SAE J684e (August@ 1974)@ with running light circuit loads not to exceed 7.5 amps per circuit. This recommended practice provides circuits for lighting@ electric brakes@ trailer battery charging@ and an auxiliary circuit color coding and protection for the wiring from hazards or short circuits. Color cording is compatible with SAE J560b. (September@ 1974) and ISO (1724-1975(E)).