🔍 Key Concepts

• Clamp-on ammeter principle – what happens to magnetic fields when equal and opposite currents pass through the same clamp? • Difference between measuring load current vs. leakage current in multi‑conductor cables • How harmonic analyzers use a clamp to sense current versus test leads to sense voltage

💭 Think About

• In figure C, does the clamp encircle one conductor, or several together? What does that do to the net magnetic field from normal load currents? • If all phase and neutral conductors are inside the clamp, what kind of current would remain for the meter to detect? Where must that remaining current be flowing? • Which of the choices specifically describes a condition where the normal load currents cancel, leaving only unbalanced or stray current to be measured?

✅ Before You Answer

• Verify whether the clamp in figure C is around one conductor only or the entire bundle of service entrance conductors. • Decide whether a clamp used this way can measure voltage at all, or only current and its harmonic content. • Think about whether the setup in figure C is intended to see normal load current, or to detect unwanted current paths (leakage).