Which category rating is needed for single-phase receptacle connected loads?

The correct category rating for single-phase receptacle connected loads is CAT II. This rating is specifically designed for devices that are connected to electrical circuits and systems that can be easily accessed and utilized by a person, typically within a commercial or residential setting.

CAT II covers equipment that is connected to the mains through a standard plug and socket, which is the case for most household appliances and tools that are plugged into wall outlets. Since these devices are exposed to lower risks than those found in industrial settings (covered by CAT III and CAT IV), CAT II is focused on protecting users from moderate transient voltages expected in this environment.

Understanding the importance of these category ratings is crucial for ensuring that technicians and users select appropriate measuring instruments that can handle the expected voltage surges and transients safely. By operating within the appropriate category, users reduce the risk of equipment damage or personal injury during testing or repair tasks.