By measuring the resistance, the multimeter can judge the size of the resistance, the quality of components, the on-off and short-circuit of the line, and the presence or absence of grounding fault (leakage). By measuring the voltage, we can not only know the voltage, but also judge the quality of components, line connection and disconnection, load size, grounding fault (that is, leakage) and other phenomena. Multimeters are generally not used to measure current, and clamp ammeters (clamp meters for short) are generally used to measure current.

For non-contact leakage, such as leakage caused by insufficient insulation strength of wires or insulators, multimeter can't measure it. In this case, it is necessary to use a more professional instrument for measuring leakage-megohmmeter.