An important piece is still missing in the electric heating and electrical standards system
Since "One" is the general requirement and "Two" is arc heating, then "Electric Heating and Electrical Three" and "Four" naturally are the safety specifications for the other two mainstream industrial heating methods.
In the family of safety standards for industrial electric heating equipment (GB 5959 / IEC 60519), parts three and four correspond to induction heating and resistance heating, respectively.
