1. Place the live and neutral wires in the jaws of the clamp meter, and any current measured is leakage current, that is, the current that returns to the ground loop.
2. Supply current (black line) and return current (white line) generate opposing magnetic fields.
3. The currents should be equal (and in opposite directions), and the opposing magnetic fields should cancel each other out. If there is no cancellation, it means that some current (called leakage current) is returning from another path, and the only other path is the ground return.
4. If a net current is detected between the supply current and the return current, the nature of the load and circuit needs to be considered.
5. A miswired circuit may allow up to half the total load current to flow through the ground system.
