The place for technical discussions about GA and flying.
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By Charles Hunt
I understand that one should only put the clamp around one of the conductors, but am perplexed that I get significantly different readings depending on whether I clamp the +ve or -ve lead.

Surely current around a circuit is constant.

Am I missing something?
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By Charles Hunt
Not aware of a zeroing function. Haven’t got it with me at the moment.

Not aware of a knurled knob on the side, is there a standard method of zeroing these modern digital things?
By Nomad63
Also, when you zero it make sure you do so with the meter as close to the position it will be when you actually clamp around the wire.
In my experience the zero calibration varies as you move them around close to other wiring, which could explain the difference in the +ve _ve wires if you are not calibrating zero when close to the measuring position.
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By Charles Hunt
Gave it a quick go yesterday and trying to get a steady zero and then get it over a wire half way down the fuselage gave meaningless results.

Current can’t flow if there’s infinite resistance so maybe a simple resistance check will show if there really is a drain problem. New master switch fitted.
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By Lerk
Current around a series circuit is constant as you say, which may mean that what you are measuring on the -ve is one leg of a parallel circuit. Ie some of the -ve is going back through the body.