Gorman-Rupp Pumps S8B1-E100 460/3 1432260 and up - Manual (Page 26)

OM-06259 S SERIES PUMPS
PAGE D - 4 TROUBLESHOOTING
the other test lead to each of the motor cable
leads in turn. Note the readings.
b. Readings will indicate resistance values in
both the power cable and motor windings.If
resistance reads infinity (
1), insulation is
good. If resistance reads between infinity (
1),
and 1 megohm, insulation is acceptable but
should be rechecked regularly. If resistance
reads less than 1 megohm, insulation should
be checked more closely and frequently.
c. If readings indicate that a ground exists, test
the stator and motor power cable separately.
Replace as required.