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Difficulty: EasyCircuit Faults and Troubleshooting

An electrician tests a de-energized heating circuit using a digital multimeter set to measure resistance. When the test probes are placed across the disconnected heating element, the meter displays an infinite resistance reading (OL). What fault condition does this measurement indicate?

  1. A
    A short circuit across the heating element
  2. An open circuit within the heating elementAnswer
  3. C
    Excessive electrical current flowing through the circuit
  4. D
    A properly functioning element operating at its rated resistance

Answer

An open circuit within the heating element
An ohmmeter displaying infinite resistance (indicated as 'OL' for open loop or out of limits) across a component means there is a physical break in the internal conductor, which defines an open circuit.

Step-by-Step Solution

1
Analyze the multimeter mode and circuit condition
The meter is configured as an ohmmeter measuring a de-energized, isolated load.
Resistance must be tested with power removed to prevent meter damage and obtain true component resistance.
2
Interpret the display reading of infinite resistance (OL)
Infinite resistance signifies that there is no continuous electrical path between the meter leads.
An intact heating element has a continuous resistive wire that provides a measurable finite resistance.
3
Identify the corresponding circuit fault
A break or gap in the internal filament represents an open circuit.
Open circuits present infinite resistance and completely prevent current flow under normal operating voltage.

Key Concept

Identifying open circuits using ohmmeter resistance measurements
Estimated Time:45s
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Topics

Circuit Faults and Troubleshooting

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