Which material is considered unsuitable as an electrical insulator?

Platinum is considered unsuitable as an electrical insulator because it is a metal with high electrical conductivity. Unlike rubber, glass, and plastic, which are materials specifically designed for their insulating properties and effectively prevent the flow of electricity, platinum allows electricity to pass through easily. This characteristic makes platinum useful in applications where conduction is required, such as in electrical contacts and interconnections, but unsuitable for situations where insulation is necessary to prevent electrical shock or short circuits.

Rubber, glass, and plastic are commonly used for insulation due to their ability to resist electrical current, thus protecting both users and devices from potential electrical hazards.