Multimeter mastery for appliance techs: field reference

Voltage is measured in parallel (across two points) with the circuit live. Resistance, continuity and capacitance are measured with the circuit de-energized and, ideally, with the part isolated from the rest of the circuit so parallel paths don't skew the reading.

A resistance reading of OL means the path is open or the value is above the selected range. Continuity mode sends a small current and beeps when resistance is low; the beep threshold depends on the model (commonly somewhere in the 0-50 Ω band), so a beep is not proof of a perfect connection.

A clamp meter senses the magnetic field around one conductor. Clamping a whole cord (both hot and neutral) cancels the fields and reads near zero; you must clamp a single conductor or use a line splitter.

Capacitance must be measured on a discharged capacitor removed from the circuit. Many meters share the capacitance position with another function and need the function button pressed.

Measurement categories (CAT II, CAT III, CAT IV) describe how much transient energy the meter and leads can survive. Plug-in appliances and their receptacle loads are CAT II locations; panels, feeders and short branch circuits near the service are CAT III; the service entrance and meter base are CAT IV. Use a meter AND leads rated for the highest category you will touch.