In article ,
Alan wrote:
If not subjected to (accidental) abuse the underlying DVM part of the
equipment may not drift that much in a well made piece of modern
equipment. Any form of accidental abuse may outwardly give an indication
that no damage has been done because the meter still gives a reading but
one or more of the ranges may be widely inaccurate. How many
electricians are proclaiming installations are safe and are writing
certificates while still using equipment that has never been checked for
accuracy since they purchased it.

Well, yes. But assuming that damage happened just after annual calibration
and certification there could be many many installations not checked
correctly.

At one time the accurately calibrated speedometers in police traffic cars
where checked for calibration daily...

--
*Experience is something you don't get until just after you need it.*

Dave Plowman London SW
To e-mail, change noise into sound.