[volt-nuts] Fluke 895A

[Charles Steinmetz]

Joe wrote:

>Just messing around, I measured a used 9 V battery. On the 100 uV 
>scale and with some interprolating of the last dial, I read 9.189795 
>V at null (with a tiny bit of wobble on the needle).

Reading an 895A to 7 significant figures is a case of "false 
precision," which can lead to overconfidence in the accuracy of 
measurement results.  Fluke specifies the accuracy of the 895A in 
differential mode as +/- (0.0025% of input + 0.0001% of range + 5 uV) 
at calibration temperature (around +/- 250 uV uncertainty for the 
measurement you describe), with calibration recommended every 30 days 
to maintain that accuracy.

Best regards,

Charles