What happens if a gauge is used above 2000m?
According to standard IEC / EN 61010-1 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%. (see point 1.4 of IEC 61010-1)
All information e.g. Specifications, measurement categories and maximum values (voltages / current) apply to these requirements unless the manufacturer indicates detailed deviations.
So, our multimeters are e.g. also specified for an extended temperature range down to -10 ° C.
When the unit is operated at altitudes above 2000m, among other things, the air pressure is lower and possibly the temperature.
Electronic components such as processors, transistors, capacitors, etc. are usually specified only for limited environmental conditions. Low air pressure could, among other things, affect components with liquids. 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.
Since then only the dielectric strength of the device would be questionable.
According to the standard, the creepage distances in the device and also in the accessories must be multiplied by a factor, e.g. times 1.48 at operation from 4001 to 5000m. That is, for the user, either the specified maximum measurement voltage would be reduced (e.g., from 600V to 300V) or the measurement category would be one level smaller (e.g., from CAT IV to CAT III) to meet the safety requirements of the standard.