Greenlee CMGRT-100A Manuel D'instructions page 24

Operation
1. See 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-100A around the loop. It should read between 4.9 Ω and 5.1 Ω.
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-100A will not measure
the resistance accurately. Make a note of the location for maintenance and proceed to the next
test location.
• A reading of < 0.01 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 OR (Out of Range) 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.
A component in the circuit is causing high leakage.
6. After taking the measurements, make a written record of the data, if necessary (date, location,
resistance measurement, and current measurement).
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