When an adapter is used for a two-hole receptacle, what is a critical requirement for safety?

Using an adapter for a two-hole receptacle necessitates that it must be attached to a known ground for safety purposes. This is crucial because grounding provides a safe path for electrical currents to follow in case of a fault, such as a short circuit. Without a proper ground connection, there is an increased risk of electric shock or fire if a fault occurs, as the electrical current could flow through unintended paths, potentially endangering users or damaging equipment.

While there are other important considerations for adapters, such as their materials and compatibility with various plug types, the grounding requirement directly addresses safety concerns related to electrical shock and equipment protection. Therefore, ensuring that any adapter used is grounded appropriately addresses these critical electrical safety standards.