Receptacles used with systems covered in Article 647 must have what characteristic?

Receptacles used with systems covered in Article 647 must have unique configurations. This requirement helps to ensure that these receptacles are used specifically with the equipment and systems they are designed for, thereby minimizing the risk of connections to standard outlet configurations that could lead to improper use or safety hazards. Unique configurations serve to prevent any unintended connections to devices that are not compatible or should not be used with the specific systems outlined in Article 647, which deals with sensitive electronic systems such as those used in healthcare facilities or laboratories. The focus on unique configurations is crucial for maintaining the integrity and safety of these specialized systems, ensuring that only the intended devices are connected.