If I want to measure any high current above 8 Amps or so I use an external shunt. I brought a 30 Amp one from Ebay
[urlhttps://www.ebay.co.uk/itm/10A-50A-75mV-Shunt-Resistor-for-DC-Current-Meter-Amp-Analog-Panel-Ammeter/352365629434?hash=item520aa0cffa:m:mylcWBpG3S8CTHdJm5diT6Q:rk:79:pf:0][/url]
I don't like when manufactures state you can measure up to 20 Amps for X amount of seconds it encourages misuse and even at 10 Amps
they state let the meter cool down.
lol especially when the internal fuse is 11 or 15 amps (and EXPENSIVE)
and no mention of ambient temperature vs 'X seconds' derating stuff,
or lead length, wire gauge, contact/connector resistance etc
or how to tell when it's cooled down enough for another shot
I wonder (not) what would happen to some of the meters out there with UNFUSED 10 and 20 amp sockets
If a clamp won't do the job and I need to break into a circuit, I use fused leads (or a knockup bodge job with croc clips
) with any value below the meter's internal fuse