Calibration Checkbox

[diditrain]

Recently had my multi-function tester calibrated and have been getting my baseline readings against a checkbox.
I have checked continuity on every resistor and all are within specification.
I have also done insulation resistance on every resistor and every one is within tolerance levels, except the 50 meg ohms one. I tested at 500v and the reading was 44.4 meg ohms.
Should i be concerned?

 

[telectrix]

how do you know that the 50Meg. resistor is 50Meg.? also at that sort of value, a bit of moisture in the air can give you a lower reading.

 

[diditrain]

Just basing it on what is says on the checkbox. +or - 5% is what i should be getting according to the user instructions

 

[Richard Burns]

If you are just starting to do your checks with the check box for the first time then assume that the 44.4 Mohm is your reference value, if it varies from this by 5% then worry!

 

[diditrain]

Could anyone tell me if there is an accepted frequency between checking your tester on the checkbox/calcard or whatever you use please?

 

[Richard Burns]

I thin I remember that the checks are recommended monthly by Elecsa, you may have other instructions with the calibration check box, but monthly seems reasonable. Just remember to keep records of your testing so you can identify trends.

 

[diditrain]

Thank`s Richard, it is a monthly recommendation in the NICEIC inspection testing and certification book 6th edition page 218, so i will roll with that.