Actually they do grasp reality in at least one point: 20% as a low end cut off for electronic cal.
Want to keep on with calipers? No sweat go to 5%, there is no real influence, and in fact may be better as the corrosion potential is reduced.
For electronic, ESD aside, the results may well become unreliable, as electron flow through wires and BNC cables (BNC to a lesser degree) can be affected by magnetic and electrical fields, hence affecting the reliability of results. Below 20% there can be sufficient static build-up to produce the fields strong enough to affect results. And since you recorded 5.7% at one point, were I doing an assessment and saw that, I would want to see the uncertainty studies taking the electric and/or magnetic fields into consideration, and the validation that results were not affected.
I actually do understand your situation, as I was in a very similar one at my previous employer. We recorded down around 5-7% during Santa Ana conditions. My argument was very easy to make as lightwave calibration suffers tremendously during high static conditions, so we were able to get humidifiers. Scopes and meters are a bit better shielded, but the real potential for effect is in the wires/cables used.
Hope this helps.
Want to keep on with calipers? No sweat go to 5%, there is no real influence, and in fact may be better as the corrosion potential is reduced.
For electronic, ESD aside, the results may well become unreliable, as electron flow through wires and BNC cables (BNC to a lesser degree) can be affected by magnetic and electrical fields, hence affecting the reliability of results. Below 20% there can be sufficient static build-up to produce the fields strong enough to affect results. And since you recorded 5.7% at one point, were I doing an assessment and saw that, I would want to see the uncertainty studies taking the electric and/or magnetic fields into consideration, and the validation that results were not affected.
I actually do understand your situation, as I was in a very similar one at my previous employer. We recorded down around 5-7% during Santa Ana conditions. My argument was very easy to make as lightwave calibration suffers tremendously during high static conditions, so we were able to get humidifiers. Scopes and meters are a bit better shielded, but the real potential for effect is in the wires/cables used.
Hope this helps.

It just makes for a better informational thread knowing the outcome, how it went, etc.