G2 Gas Fitter Practice Exam

When taking a DC voltage measurement, if the needle on the analog meter moves below zero, what does this indicate?

1. Meter malfunction

2. Correct polarity

3. Test leads are reversed

4. Insufficient voltage

The correct answer is: Test leads are reversed

When the needle on an analog meter moves below zero while taking a DC voltage measurement, it indicates that the test leads are reversed. In a typical scenario, the positive lead should be connected to the positive terminal of the voltage source and the negative lead to the negative terminal. If these connections are swapped, the meter will show a negative reading because the polarity is opposite to what the meter expects for a positive voltage measurement. Understanding this concept is crucial for accurate measurements in electrical work. Recognizing the direction of the needle and the implications it has regarding connections ensures that readings are interpreted correctly, which is particularly important in fields like gas fitting, where proper functioning of electrical components can impact safety and efficiency. The other options do not correctly explain the situation. If the meter were malfunctioning, it might provide an inconsistent reading, not necessarily a negative one. Correct polarity would lead to a positive reading if the connections are made as expected. Insufficient voltage typically results in a reading close to zero, but not a negative one, as the meter would simply reflect the low voltage level rather than indicating reversed polarity.