In addition to the meter, which component must also have the proper "CAT" rating?

The meter leads must have the proper "CAT" rating because they directly connect the meter to the electrical circuit being tested. The "CAT" rating, or category rating, indicates the safety level of the equipment when measuring in environments with potential electrical hazards. For instance, a CAT II rating means the meter leads can safely be used in applications rated for up to 300 volts typically found in appliances, while a CAT III rating may be required for installations and distribution systems operating at higher voltages. Ensuring that the meter leads match the CAT rating of the meter is crucial for protecting both the user and the equipment, as inadequate ratings can lead to electrical shock or meter damage.

The other components, while important, do not directly affect the measurement process and safety in the same way. For example, the power source does not need to have a CAT rating since it is the source rather than the measuring tool. Similarly, the circuit board’s design may not be directly related to the safety of the measurement process, and the user manual primarily provides instructions but does not require a CAT rating to ensure safe operation. Thus, having meter leads with the proper CAT rating is vital for safe electrical measurements.