Ohmmeters are to be used only on circuits that are de-energized.

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Multiple Choice

Ohmmeters are to be used only on circuits that are de-energized.

An ohmmeter measures resistance by injecting a small current from its own internal battery into the circuit. For that reading to be accurate and safe, the circuit must be de-energized so there’s no external voltage or current interfering with the meter’s test signal. If the circuit is live, the existing power can distort the reading, and the meter or components could be damaged or pose a shock risk. Before measuring resistance, power must be removed and any capacitors discharged to prevent residual charge from affecting the result. Because of these safety and accuracy concerns, the correct approach is to use the ohmmeter only on de-energized circuits.

An ohmmeter measures resistance by injecting a small current from its own internal battery into the circuit. For that reading to be accurate and safe, the circuit must be de-energized so there’s no external voltage or current interfering with the meter’s test signal. If the circuit is live, the existing power can distort the reading, and the meter or components could be damaged or pose a shock risk. Before measuring resistance, power must be removed and any capacitors discharged to prevent residual charge from affecting the result. Because of these safety and accuracy concerns, the correct approach is to use the ohmmeter only on de-energized circuits.

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