Sekundäärieristyksen

Sekundäärieristyksen, also known as secondary insulation, is a safety feature found in some electrical appliances and equipment. It is a second layer of insulation that provides protection in case the primary insulation fails. This added protection is crucial for preventing electric shock to users.

The concept of secondary insulation is distinct from basic insulation. Basic insulation is the minimum requirement for electrical safety, designed to prevent direct contact with live parts under normal operating conditions. Secondary insulation, however, acts as a fallback. If the basic insulation is damaged due to wear, tear, or misuse, the secondary insulation ensures that the user remains protected from hazardous voltages.

Electrical devices employing secondary insulation are often designed with a double-insulated construction. This typically involves a robust outer casing made of non-conductive material, which completely encloses the internal components that have their own basic insulation. In some cases, this might involve both insulating materials and protective spacing.

The use of secondary insulation is particularly common in portable electrical tools and appliances where the risk of insulation damage might be higher. Appliances that meet the requirements for secondary insulation are often marked with a symbol of a square within a square. This designation signifies a higher level of electrical safety compared to equipment with only basic insulation.