Ok so I bought a new field piece the other day and don't ask me why but I was farting around with it and clipped the amp probe around the power cord for the tv and the tv instantly turned off, as soon as I removed it the tv restarted. I tried it three times and all three times the same thing. Can anyone explain this as all my co workers are baffled?
You changed the circuit reactance when you put the jaws around the line.
In the 1990's, TV makers had gone to solid state power supplies and single board construction. In fact, repair of discreet components was rarely worthwhile. A typical Zenith (made in Mexico then) failure would mean a new board.
These solid state TV's use a sequence of operation involving three of four IC's, and they can be pretty finicky. The RCA tech booklet devoted an entire page of description to explain the steps the TV uses once the little pushbutton (or the remote) is pressed to get to the point of energizing the HV drive and the various amps and such, which when it is all over, results in the set being "on."
By changing the reactance of the line, you upset the delicate balance required to maintain that state of well being.
[Avatar photo from a Florida training accident. Everyone walked away.] 2 Tim 3:16-17
LCD, LED, Plasma, or old school TV? The power supplies in some newer TV's have built in "surge protection", but I'm not sure why a clamp on ammeter would trigger it. If you want to know the power draw of your TV get a "kill-a-watt" plug in meter.