The C4-212-A-B Test Switch is a dedicated switching accessory from Multi-Amp Corp, identified by the part number C4-212-A-B. This model appears in historical catalogs and secondary listings as a Multi-Amp product—and is sometimes associated with States test configurations in older documentation—marking it as a component used to route test signals within protective relay test equipment. In its role within legacy test systems, the C4-212-A-B provides a manual means to select or isolate circuits during relay and instrument testing, enabling technicians to configure test setups without altering wiring harnesses.
