Unlike an MOT certificate a calibration certificate doesn't generally have an expiry date, just the date it was last verified as accurate. Many of the contractor schemes will require a record of regular checks with a known set of test values such as a proprietary check box. If you have no secondary reference checking it is hard for you to verify consistency of the readings. Whereas if you have regular record of checks since the last calibration and there is no significant deviation of any results, it can be considered that the meter is still within tolerance. I have heard that some of the contractor schemes do not expect to see annual calibration but they do expect to see a regular self check record log e.g. monthly, bi-monthly but certainly not exceeding quarterly. But they do understand the level of self checking would be commensurate with the amount of use the meter is put to. I would suggest if the meter is used infrequently, it would be wise to do a formal self check each time before you use it?
never calibrated any of my multimeters
I NEVER trust a cheapo multimeter. Nothing short of a Fluke model 93 for me.
Imperial of course , they're much better than these continental volts .
never been asked for calibration for my multimeter....
