An ohmmeter should never be connected to which of the following?

An ohmmeter should never be connected to which of the following?

• A. Charged capacitor until it has been discharged
• B. Live power line
• C. A resistor in series
• D. A burned-out component

Answer: (A)

Ohmmeters push a small current from their internal battery to measure resistance, so they are active sources of voltage. A charged capacitor holds stored energy that can dump into the meter when you connect them. That sudden surge can overload or damage the meter’s internal circuitry (fuse, transistors, and other components) and can create a safety hazard. Because of this stored energy, you must discharge capacitors safely and power down the circuit before measuring resistance. In practice, this is the scenario that most clearly demands avoiding connection to an ohmmeter, since it can cause immediate, energy-driven damage.

Ohmmeters push a small current from their internal battery to measure resistance, so they are active sources of voltage. A charged capacitor holds stored energy that can dump into the meter when you connect them. That sudden surge can overload or damage the meter’s internal circuitry (fuse, transistors, and other components) and can create a safety hazard. Because of this stored energy, you must discharge capacitors safely and power down the circuit before measuring resistance. In practice, this is the scenario that most clearly demands avoiding connection to an ohmmeter, since it can cause immediate, energy-driven damage.