BS 3535:1962

Single-phase and polyphase, double-wound transformers up to 6.5 kVA, input voltages up to 650 volts, output voltages up to 110 volts. Electrical, mechanical construction affecting safety, durability, reliability in service. General requirements and particular requirements for: transformers for use with toys, bell transformers, transformers for domestic purposes, for industrial and similar purposes, for hand-lamps and bench-lamps, unshrouded transformers.