This Standard applies to single-phase isolating transformers, stationary or portable, intended to supply a voltage to bell circuits or to similar equipment.
The requirements of this Standard apply also to transformers intended for use in locations where explosions are liable to occur, or where there is a danger of inflammability or where there is a considerable amount of dust, but compliance of these transformers with the requirements of this Standard does not ensure their fitness for use in these particular locations, unless they comply with other requirements or additional requirements that are not mentioned in this Standard.