What happens when a measuring device is used above 2000m altitude?

According to the IEC/EN 61010-1 standard, there are so-called reference conditions (ambient conditions), e.g.

• Altitude up to 2000m,
• temperature range from 5°C to 40°C
• a relative humidity of up to 80%. (cf. point 1.4 of IEC 61010-1).
  

All information e.g. specifications, the measurement categories and maximum values (voltages / currents) are valid for these requirements, if the manufacturer does not specify detailed deviations.

For example, our multimeters are also specified for an extended temperature range down to -10°C.

If the device is operated at altitudes above 2000m, among other things, the air pressure is lower and possibly also the temperature.

Electronic components such as processors, transistors, capacitors, etc. are usually also specified for limited environmental conditions. If the air pressure is low, components containing liquids could be affected, among other things. This would particularly affect batteries and LCD displays.

According to our manufacturers, both the LCD displays used and the batteries are suitable for use above 2000m.

Another issue would be the dielectric strength of the device:
According to the standard, the creepage distances in the device and also on the accessories must be multiplied by a factor, e.g. times 1.48 for operation from 4001 to 5000m. This means that for the user, either the specified maximum measurement voltage would be reduced (e.g. from 600V to 300V) or the measurement category would be reduced by one level (e.g. from CAT IV to CAT III) in order to meet the safety requirements of the standard.