Before using a multimeter to check voltage on a breaker, you should:

• A. Turn off the power and test with a known source
• B. Check the meter with a known power source
• C. Inspect the breaker labeling
• D. Wear insulated gloves

Answer: (B)

Verifying the meter’s function with a known voltage source is essential before measuring a breaker. This checks that the meter is actually measuring correctly, the battery isn’t dead, and the test leads are in good condition. If the meter is malfunctioning or the leads are damaged, you could get inaccurate readings on the breaker, which can lead to unsafe conclusions about the circuit. Using a known live outlet to confirm the meter reads the expected voltage gives you confidence that subsequent measurements on the breaker reflect reality. Safety gear and correct wiring practices matter too, but they don’t confirm the instrument’s accuracy the way testing against a known source does.