Operation - Greenlee CMGRT-100 Instruction Manual

Operation

1. See Using the Features.
2. Turn the unit on, selecting the appropriate features (turn the speaker on or off, change the alarm
setpoint, etc).
3. See Typical Applications for specific measurement instructions.
4. Test the unit on a known functioning circuit or the test resistance loop. To use the test resistance
loop, clamp the CMGRT-100 around the loop. It should read between 24.2
Note: This value is for ambient temperature between 20 C and 25 C (68 F and 78 F). It may
differ a few counts below or above this temperature.
• If the unit does not function as expected on a known functioning circuit or the test resistance
loop, replace the battery.
• If the unit still does not function as expected, send the unit to Greenlee for repair. See the
address shown under Warranty.
5. Take the reading(s) from the circuit or component to be tested.
• If the ground current exceeds 5 A or if the noise exceeds 50 V, the CMGRT-100 will not measure
the resistance accurately. Make a note of the location for maintenance and proceed to the next
test location.
• A reading of < 0.1 may indicate that the cable is part of a closed loop; for example; when two
bonding conductors are connected to the same enclosure and ground rod.
• A high resistance reading or OL (overload) may indicate any of the following:
The cable is not grounded at both ends (a lack of a ground, or a lack of a path back to the
system neutral).
The ground rod is in poor condition.
The ground circuit is broken, or open.
The bonds on the rod or splices are of poor quality. Check for buried split butts, clamps, and
hammered-on connections.
6. After taking the measurements, make a written record of the data, if necessary (date, location,
resistance measurement, and current measurement).
CMGRT-100
and 25.8 .
9