XPost: sci.electronics.equipment   
   From: rich@example.invalid   
      
   In sci.electronics.equipment Commander Kinsey  wrote:   
   > On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull    
   wrote:   
   >   
   >> On 2/07/2020 10:41 pm, Ralph Mowery wrote:   
   >>> For a real scare you should see some of the safety movies that   
   >>> Fluke put out.  They show under test conditions what can hapen to   
   >>> inexpensive meters and their meters under different conditions like   
   >>> having the meter set for amps and putting across a 480 volt circuit   
   >>> that has plenty of amps .   
   >>>   
   >> Ahh the old "Leaving it on amps" trick.  How many of us can say they   
   >> never did it ?   
   >   
   > I find it crazy that you can select volts and have the wires in the   
   > amps holes.  The switch should change the contacts.  I've broken a   
   > meter doing that, just measuring the voltage on a car battery.  £100   
   > meter, but UNFUSED FFS!  At least the mA range was fused, but they   
   > couldn't be bothered putting in a 20A fuse for the big range....   
      
   The separate amps jacks exist for at least two reasons:   
      
   1) If the range switch also switched in/out the current shunt, then the   
   user could accidentally create a short circult across the probe tips   
   simply by turning the range switch to or across the amps measurement   
   ranges.  Even if they were quickly turning /across/ the amps settings   
   ranges, a brief short circuit would be created, which would cause   
   damage to the meter as well as the device under test depending upon   
   what was connected at the time.   
      
   2) By having the amps jacks separate, the range switch itself does not   
   have to have contacts beefy enough to carry the current for the amps   
   settings.  Remember, when measuring amps, the current being measured   
   flows *through* the meter itself.  This would require very different   
   (and likely much more expensive) range switch contacts.   
      
   Some meters do have sensors for the amps jacks that sound an alarm if   
   the probes are inserted in the amps jacks but the range switch is on a   
   different setting than amperes.   
      
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