Kewtech KT62 Instruction Manual page 18

Insulation tests 6 When testing is complete release the test button before disconnecting
Never turn the function dial whilst the test button is depressed as
this may damage the instrument. Never touch the circuit, test lead
tips or the appliance under test during insulation testing.
Always release the test button first after testing before removing
the test leads from the circuit. This is to ensure that charges
stored in the circuit capacitance have been totally discharged.
Note:
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the test leads from the circuit or from the appliance. This will ensure
that the charge built up by the circuit or the appliance during insulation
test is dissipated in the discharge circuit. In the discharging process, an
LED illuminates and the live circuit warning buzzer will sound.
If the reading measured greater than 200MΩ the over range
reading 'OL' will be displayed.
CAUTION