CSLB C-10 Electrical ContractorSafety and TestingEasy
An electrician is troubleshooting a motor circuit and needs to measure the resistance of the motor windings. Which of the following instruments is most appropriate for this task?
- AVoltmeter
- BClamp-on ammeter
- COhmmeter
- DWattmeter
Show answer & explanationAnswer & explanation
Correct answer: C. Ohmmeter
An ohmmeter is specifically designed to measure electrical resistance in ohms. It is the correct tool for checking motor winding resistance.
Why the other options are wrong
- A. A voltmeter measures voltage, not resistance.
- B. A clamp-on ammeter measures current, not resistance.
- D. A wattmeter measures real power (watts), not resistance.
Ohmmeter
An electrical instrument used to measure electrical resistance in ohms (Ω).
- Measures resistance
- Requires circuit to be de-energized
- Used for troubleshooting shorts, opens, and winding integrity
Memory trick: AVO: Always Verify Ohms!