IEC 61439-6:2012 lays down the definitions and states the service conditions, construction requirements, technical characteristics and verification requirements for low voltage BTS (see 3.101) as follows: - BTS for which the rated voltage does not exceed 1 000 V in case of a.c. or 1 500 V in case of d.c.; - BTS intended for use in connection with the generation, transmission, distribution and conversion of electric energy, and for the control of electric energy consuming equipment; - BTS designed for use under special service conditions, for example in ships, in rail vehicles, and for domestic applications (operated by unskilled persons), provided that the relevant specific requirements are complied with; - BTS designed for electrical equipment of machines.