KNOVA KN 8052 Manual page 12

Non-contact voltage detection
1. When the meter head is close to the AC voltage field, the LED light
the close distance is about 30mm from the AC voltage field.
!
WARNING
Even without LED indication, the voltage may still exist. Do
not rely on non-contact voltage detector to determine the presence
of voltage wire, Detection operation may be subject to socket design,
insulation thickness and different type and other factors
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