“A Stitch in Time...”

Short-Time Readings
For short-time readings of insulation resistance, operate the instrument for
a definite length of time, either 30 seconds or 1 minute, and read at the end
of that time. Continue cranking steadily at slip speed until the reading has
been taken. Make future tests with the same length of operating time.
Time-Resistance Method
When using a hand-cranked instrument, operate continuously for 1 minute.
Take a reading at the end of the first 30 seconds and another reading at the
end of the minute.
When using a motor-driven or rectifier-operated instrument, the time
intervals are usually 1 minute and 10 minutes from the time the testing
voltage is applied. Or, time-resistance curves may be taken over a period of
10 to 30 minutes or longer.
Voltage Scales
Some insulation testers may be supplied with a voltage scale to check for
the absence of voltage before insulation testing. As explained in the Safety
Precautions section, however, insulation testers should never be connected
to energized lines or equipment when operated in any of the Insulation Test
or Resistance Test modes.
A STITCH IN TIME 35