Ac volt and amp meter help

[asbo]

I have on of these:

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Measurement range: AC Voltage: AC 80-300V
                                AC Current: AC 1-100A
Accuracy: 1%
Display: LCD screen display (Screen visual dimension: 43 x 25 mm)
Power consumption: < 0.2VA
Measurement speed: twice per second

Despite the listing saying it would come with a wiring diagram it didn't.
Now to me red and black wires mean DC(except in old house wiring. But maybe that's just a UK thing?) but after messaging the seller apparently not in this case. So I put some mains voltage in it and it read 240v which is correct.
The seller said you have to wire something in series and it will read the amps, now this make sense except those wires are tiny, won't they melt if too much current goes through them? Whilst I'm never going to have 100A going through there it does say it supports that so I'm quite confused.
Anyway I wired a switching DC power supply and some LEDs in series, it displays 40V and shows no amps, the green amp bit doesn't even light up.
Now I never finished my electrical engineering course but I didn't think the voltage would drop to 40v with a tiny load like that?

Help please!

[xman]

I would say you need a "shunt". I use similar on my solar setup but Blue LED and backlite and the shunt comes with it. You also have the choice of it being self powered or via a separate supply to drive the display. By the way, you really need to get this right or smoking of the device may result. You may want to look back on my "Quads and a New Lifestyle" posts and see the ones I've used on the solar/ distribution board. Those meters were a couple of dollars each and have been working oerfectly for over a year now. I have info on them which you could use but that will be a couple of days. The farm is waiting.

[asbo]

I would say you need a "shunt".

ah yes I have a vague memory of hearing about them, never actually used one or seen one even.
I'll go have a read

And have fun at the farm, good hunting