Kaksoiseristystä

Kaksoiseristystä, known in English as double insulation, is an electrical safety standard used in electrical equipment. It is designed to protect users from electric shock by providing two independent layers of insulation between live electrical parts and the user. This is achieved through a combination of basic insulation and supplementary insulation. Basic insulation is the primary layer that prevents contact with live parts under normal operating conditions. Supplementary insulation is an additional layer of protection that functions even if the basic insulation fails.

Equipment that meets the double insulation standard is typically marked with a symbol depicting a square within a square. This indicates that the equipment does not rely on earthing for safety, meaning it can be used with a two-pin plug rather than a three-pin plug that includes an earth connection. This feature is particularly beneficial in environments where earthing might be unreliable or absent.

The concept of double insulation originated from the need to enhance electrical safety, especially for portable appliances and in situations where the risk of fault currents to earth is higher. By eliminating the need for earthing, it simplifies the design of appliances and reduces the potential for hazards associated with faulty earthing systems. Many modern appliances, such as hairdryers, power tools, and kitchen appliances, are manufactured with double insulation. Adherence to double insulation standards is regulated by various international and national safety organizations.