Gas Fitter Practice Test

When checking a circuit of unknown voltage, which scale should be selected on an analog meter?

1. 0-30 volts

2. 0-125 volts

3. 0-250 volts

4. 0-600 volts

The correct answer is: 0-600 volts

When checking a circuit of unknown voltage, it is prudent to select the highest scale available on an analog meter, which in this case is 0-600 volts. Using the highest scale ensures that you can accurately measure the voltage without exceeding the meter's capacity, which could damage the meter or lead to incorrect readings. By selecting the highest range, you cover a wider potential span of voltages, allowing for flexibility in possible readings. If the voltage is indeed high, you will have the capability to measure it without risk of the meter becoming overloaded. Once the measurement is taken, you can switch to a lower scale for finer readings if necessary. This approach prevents the situation of selecting a scale that is too low for the voltage present, which can lead to meter damage or inaccurate measurements. Therefore, selecting the 0-600 volts scale is the safest and most effective choice when the voltage level is unknown.