Calibration Inquiry

Dear Experts,

We have this surface resistance meter that was calibrated at a range of 10^11 ohms higher limit. My question is that, do we need to perform calibration at a range of 10^12 or higher? because our calibration is only capable at 10^11 range. but our meter is capable to measure greater than 10^11 ohms.
please advise.

thank you.

It really depends on the meter and the setup. If the equipment is calibrated, then it should measure the entire range of the equipment. That does not mean the system (probes, wires, meter) is capable of measuring a resistance that high. To check that, try to measure an insulator with the probes, wires and meter. That reading will inform you of the highest resistance that the system can measure.
For example, when nothing is connected to the meter, the meter should go to overload or the highest reading the meter is capable of. In this example, say the meter top reading is 10E14 ohms.
Next connect the wires and probes and try to measure an insulator. In some cases the reading is now in the 10E12 range due to leakage in the wires and probes. If the reading is 10E9 or 10E10 then that is the highest reading you can make.
The point is, even if you calibrate the meter for 10E14 ohms, the system may not be capable of reading a resistance that high.

i see.
thank you very much John for the clarification.