PaulEngr wrote:
Not sure why this would matter. Testing/calibration was required in 250.3 in the 2012 edition.
Testing for calibration is typically advertised to NIST or ISO standards. Either way a certified test source is used to generate voltages/currents at the extremes of the meter range and the readings are recorded (usually 2 or 3 points maximum). Then an error is calculated and compared to the data sheet to say if it meets manufacturer specification or not.
This is different compared to say UL testing which includes testing under various failure prone scenarios.
Hey there, do you have an updated reference as to whether or not meters are required to be calibrated for live dead live checks?
I suspect they are but I can understand an argument against them being required (live-dead-live being qualitative vs quantitative).
Thanks!