USCG Exam PracticeElectrical measuring devices and instrumentation
When connecting an ammeter to measure current in a DC circuit, the technician must connect it in which manner?
- A. In parallel across the load, with the range set to the lowest available
- ✓ In series with the load, after opening the circuitCorrect
- C. In parallel across the voltage source, on the highest range
- D. In series with the voltmeter already connected across the load
Why B is correct
An ammeter has very low internal resistance and must be connected in series so all circuit current passes through it; the circuit must be opened to insert it. Connecting an ammeter in parallel across a voltage source would drive a destructive short-circuit current through the meter.
Cited:NEETS Mod. 3 §1-2