What is the universal symbol indicating "double insulated" tools?

The universal symbol indicating "double insulated" tools is represented by a square within a square. This symbol serves to identify tools and equipment that have been designed with double insulation, meaning they have two layers of insulating material that protect the user from electrical shock. This design feature is particularly important for ensuring safety while using electrical tools in environments where exposure to conductive surfaces may occur.

The square within a square symbol indicates that the tool is built to provide a higher level of protection compared to single insulated tools, which typically only employ one layer of insulation. This dual protection reduces the risk of electrical shock, making it a vital consideration for users working with power tools in potentially hazardous conditions. Understanding and recognizing this symbol is crucial for anyone involved in construction, renovation, or any field where electrical tools are utilized, as it ensures that proper safety standards are being followed.