Good morning Flash
It only works when you can separate the wires and put the amp clamp around the hot one.
You are certainly correct that you must separate the conductors and only put the amp clamp around one of the conductors at a time.
However it does not matter which conductor you put in the amp clamp, the ungrounded (hot) or the grounded (neutral) you will get a reading on both. The reading should be equal on both the ungrounded and grounded conductor.
If they are not exactly equal the appliance has a problem with leakage current and you should find the 'difference' carried on the grounding conductor.
Bob
