The idea of 2 core leads and extra insulation to give double fault to danger was sort of out there long before they were called that by the IEC - and they created the formal  classes I and II we know from 1969 onwards, and at about the same time classes 0 (single insulation no earth )and 0A (single insulation and earth by separately  installed flying lead only) were generated to cover less safe existing kit as well, but then immediately deprecated. (still commonly found  in developing world however).

Black and Decker had a formal 'DI programme' in the early 1970s, re-modelling their range of drills, saws etc to the new standards, but companies like Morphy Richards had been making what we would consider all-insulated hair dryers for some time by them - for example  the HDA 2 (Hair Dryer All-insulated model 2) is a 1950s beast. There may even have been an HDA 1 before it, there was certainly an HDA3 in the early 1960s.

However some of these pre 1969 products were sort of only halfway there, and used non-metallic screws and funny things like that, which nowadays would not be considered OK.

Mike.

Thanks Mike, much appreciated.

Thanks Mike, much appreciated.

To quote from the foreword of BS 2754 : 1976 - Memorandum. Construction of electrical equipment for protection against electric shock :

'When this memorandum was first issued as BS 2754 : 1956 its purpose was to explain the principles and requirements for the, then, new constructional method of double insulation.'

The concept of double insulation as a method of protection against electric shock has therefore been around from at least the mid 1950s onwards.