A thermal camera tells you where something is running hot. A meter tells you why, by measuring the actual electrical values. Here is what the main types do.
Digital multimeter
The general-purpose tool. It measures voltage, resistance and often continuity, and may also measure current and other values. Good for checking outlets, batteries, switches and wiring.
Clamp meter
A clamp meter measures current by clamping around a single conductor, so you do not need to break the circuit. That makes it safer and faster for checking how much load a circuit is drawing. Many also measure voltage and include a non-contact voltage detector (NCV) that senses live conductors without touching them. Example: the ANENG PN107 digital clamp meter.
Insulation tester
An insulation tester, sometimes called a megohmmeter, applies a high test voltage to a conductor and measures how well its insulation resists leakage. It is used on motors, cables and wiring to find degrading insulation before it fails. It must only be used on circuits that are de-energized and isolated. Example: the ZOYI ZT-1000R, which combines an insulation tester with a multimeter.
True RMS
On circuits with non-sinusoidal loads, a basic meter can read inaccurately. True RMS meters handle those loads correctly, which matters on modern electronics-heavy circuits.
Safety ratings
Meters carry a category rating (CAT II, III or IV) and a maximum voltage. The category describes where in an electrical system the meter is designed to be used, with higher categories for equipment closer to the power source. Never use a meter in a location or at a voltage above its rating. Check the rating printed on the meter itself and on the product listing before using it on panels.
Using them with a thermal camera
Spot a warm breaker on camera, then clamp the circuit to see if it is overloaded. Spot a hot connection, then confirm voltage drop with a multimeter. See thermal imaging for electrical inspections.
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