Electrical meters are so commonly used by service technicians that most take them for granted. Rarely are meters considered a source of potential danger. But the electrical meter, being as versatile and easy to use as it is, can very easily become the path of current between the power supply and the technician!
In most cases, the voltage supply for HVACR equipment does not exceed 600 V. For such applications, it is important to use a meter with a Category III 1,000-V rating minimum. This rating means that the meter has the proper circuit protection (fusing) and insulating leads to be used safely in most HVACR applications. This figure shows a typical digital multi-meter.