User’s Manual Ground Resistance Clamp-On Tester MODEL 382357
Warranty EXTECH INSTRUMENTS CORPORATION (a FLIR company) warrants the basic instrument to be free of defects in parts and workmanship for one year from date of shipment (a six month limited warranty applies on sensors and cables). If it should become necessary to return the instrument for service during or beyond the warranty period, contact the Customer Service Department at (781) 890-7440 EXTENSION 210 for authorization or visit www.extech.com for more information.
Description 1. Jaw Assembly 2. Hold Button 3. Rotary Selector Switch 4. LCD Display 5. Record Button 6. ▼(decrement) Button 7. ▲(increment) Button 8. Function Button 9. Measurement Trigger 1 2 3 9 4 5 8 7 6 Display Symbols 1. REC: Indicates data logging in progress 2. NO. Indicates the READ function 3. : Clamp jaws are not fully closed 4. NOISE: Excessive noise on the ground conductor or rod 5. •))): Hi Lo alarm position 6. Function or Record display 7.
Specifications General Specifications Resistance Test Frequency: 3.333 kHz (15mV rms approx.) Max Conductor size 0.9” (23mm) Display 4-digit (9999 count) display Sampling rate 0.5 seconds Memory 116 records Datalogging sample rate 1 to 255 seconds Power supply One 9V battery Power consumption 40mADC Battery Life 3000 measurements Temp. Coefficient 0.
Ground Resistance (Autorange) Specifications Range Resolution Accuracy (of reading) 0.025 to 0.250Ω 0.002Ω ± (1.5% + 0.05Ω) 0.250 to 1.000Ω 0.02Ω ± (1.5% + 0.05Ω) 1.001 to 9.999Ω 0.02Ω ± (1.5% + 0.1Ω) 10.00 to 50.00Ω 0.04Ω ± (2.0% + 0.3Ω) 50.01 to 99.99Ω 0.04Ω ± (2.0% + 0.5Ω) 100.0 to 200.0Ω 0.4Ω ± (3.0% + 1.0Ω) 200.1 to 400.0Ω 2Ω ± (5.0% + 5Ω) 400.0 to 600.0Ω 5Ω ± (10% + 10Ω) 600.
Operation Note: Ensure that the jaws are fully closed before testing. Note: DO NOT clamp on to any conductor or open the clamp jaws during the start-up self-calibration (self-cal is identified by the LCD counting down from CAL7 to CAL1). Ground Resistance Measurements 1. Open the clamp jaws and check that all surfaces are clean and free of dust, dirt, or any foreign substances. Clean if necessary. 2. Forcefully snap the clamp jaws open and closed several times. 3.
High and Low Alarm 1. Turn the meter on by moving the rotary switch to the •))) position. 2. Press the FUNC button to view and adjust the “HI” alarm value.. 3. Press ▲ or the ▼ button to increase or decrease the value. Hold down the button to increase the speed of adjustment. The value can be incremented from 0 to 1500 ohms and then OL (overload). The value will roll over to 0 after OL is displayed. 4.
Measurement Principles Typical multi-grounded distribution system Req If the parallel ground resistances, R1, R2, R3,etc, up to Rn are combined as Req, then only Rg and Req are left in the circuit I V Rg If a constant voltage is applied to the circuit, the following equation applies: V = R g + Req I Req = where: 1 , i = 1,2,...n 1 ∑ Ri If Rg and R1, R2, R3…Rn, are approximately the same, and n is large (200, for example), then Req will be much less then Rg and may possibly approach zero.
Applications Telephone-Electrical Ground Rods 1. Remove any protective covering from the ground conductor 2. Turn the meter switch to the Ohm Ω function. 3. Once the start-up calibration procedure is completed clamp on to an electrode or ground rod. 4. Allow several seconds for the meter to settle and then note the reading. Cellular Transmission Towers WARNING: Use extreme care when making measurements around transmission towers; High Voltage may be present.
Service Entrance Note: Multiple ground rods, multiple grounds i.e. ground rod(s) and water pipe grounds, or a combination may be present depending on the particular situation. In these situations it is necessary to make your measurements between the service-entrance neutral and all subsequent ground points. Distribution Panel Water Pipe Ground Rod 10 382357 V2.
Troubleshooting 1. Snap the jaws open and closed two or three times before turning the meter on 2. Do not clamp on to any device during the power-up initialization sequence. 3. Snap the jaws two or three times after clamping on to the ground electrode or rod. 4. Slight amounts of drift may occur at high resistance measurements; this is normal and should not be cause for concern. Blank display or any failure mode Replace the battery before proceeding.
Maintenance General Care Store the ground resistance tester and reference loop in its case when not in use. A damp cloth may be used to clean any surface dirt from the meter. Never use harsh detergents, abrasives, solvents, or cleaners on the meter. Battery Replacement When the low battery symbol appears on the display, replace the meter’s 9V battery. Use a high quality alkaline battery whenever replacement becomes necessary. 1. Remove the two rear screws and open the meter housing. 2.
