External parts of insulating materials, deterioration of which might cause the electrical appliance or plastic conduit to become unsafe, shall be sufficiently resistant to deformation at elevated temperatures. Compliance is checked by subjecting plastic parts or conduits made of insulating materials to a ball pressure test.
The Ball Pressure Apparatus consists of a hardened and ground carbon steel ball held in a suitable adopted. The adopter carries a stirrup arrangement to apply the specified load on the test specimen placed on a flat surface.
A metallic stand having a flat horizontal platform for placing the test specimen on is also supplied with the equipment.
IS 302 –1979 : General and Safety Requirements for Household and Similar Electrical Appliances
Clause 30 : Resistance to Heat
IS 366 – 1991 : Electric Iron – Specification
IS 1293 – 1988 : Specification for Plugs and Socket-Outlets of 250 volts and Rated Current up to 16 Amperes