In a double-insulated product, two systems of insulation are provided instead of grounding. No grounding means is provided on a double-insulated product, or is
a means for grounding to be added to the product.
Servicing a double-insulated product requires extreme care and knowledge of the system, and is to be done only by qualified service personnel. Replacement
parts for a double-insulated product must be identical to the parts they replace. A double-insulated product is marked with the words "DOUBLE INSULATION"
or "DOUBLE INSULATED". The symbol (square within a square) is also able to be marked on the product.