Which instrument would you use to measure current in a control circuit and what setting would you use?

Prepare for the NCCER Electrical Level 2 Control Systems and Fundamental Concepts exam. Utilize flashcards and multiple choice questions with hints and explanations. Ensure success on your exam!

To measure current in a control circuit, use a tool designed to measure current—either a multimeter in current mode or a clamp-on ammeter. If you’re dealing with AC, set the meter to the RMS range so you read the true effective current (the value that corresponds to heating and power). True RMS is especially important if the current waveform isn’t a perfect sine wave. A clamp-on ammeter is ideal for live measurements because it doesn’t require breaking the circuit; just make sure the clamp surrounds a single conductor, not the whole bundle. The other instruments aren’t for measuring current: a voltmeter reads voltage, an ohmmeter measures resistance, and a megohmmeter tests insulation resistance. Always choose a range that’s high enough to avoid overrange but low enough to give a precise reading.