Extech Instruments 382356 User manual

User’s Manual

Ground Resistance Clamp On Tester

MODEL 382356

382356 V2.0 5/03

WARRANTY

EXTECH INSTRUMENTS CORPORATION 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 for authorization. A Return Authorization (RA) number

must be issued before any product is returned to Extech. The sender is responsible for

shipping charges, freight, insurance and proper packaging to prevent damage in transit.

This warranty does not apply to defects resulting from action of the user such as misuse,

improper wiring, operation outside of specification, improper maintenance or repair, or

unauthorized modification. Extech specifically disclaims any implied warranties or

merchantability or fitness for a specific purpose and will not be liable for any direct, indirect,

incidental or consequential damages. Extech's total liability is limited to repair or

replacement of the product. The warranty set forth above is inclusive and no other

warranty, whether written or oral, is expressed or implied.

Introduction

Congratulations on your purchase of Extech’s 382356 Ground Resistance Tester. This

Clamp-on device allows the user to measure the ground resistance of a ground rod without

the use of auxiliary ground rods. This device can only be used on multi-grounded systems.

It is not necessary to disconnect the ground under test. Proper use and care of this meter

will yield years of reliable service.

Safety

Safety is the responsibility of the operator. Only qualified technicians should operate this

meter.

Use extreme caution when operating the meter near energized electrical equipment.

Do not attempt to use this meter to twist or pry the ground electrode or ground wire away

from grounded equipment.

All metal objects or wires connected to the electrical system under test should be assumed

to be lethal until tested. Grounded systems are no exception.

Ensure that the batteries are inserted correctly in the battery compartment.

Remove the batteries from the meter if the meter is to be stored for long periods.

WARNING: If the meter is used in a manner not specified by the manufacturer, the built in

protections provided by the meter may be impaired.

382356 V2.0 5/03

International Safety Symbols

This symbol, adjacent to another symbol or terminal, indicates the user

must refer to the manual for further information.

This symbol, adjacent to a terminal, indicates that, under normal use,

hazardous voltages may be present

Meter Description

1. Jaw Assembly

2. Hold Button

3. Rotary Selector Switch

4. LCD Display

5. Measurement Trigger

Display Symbols

ΩOhms.

mA, A milliamps, Amps.

•))) Continuity.

NOISE Annunciator for excessive noise on the ground conductor or rod.

Indicates that the clamp jaws are not fully closed.

Low Battery.

382356 V2.0 5/03

Specifications

General Specifications

Resistance Test Frequency: 1.667KHz (15mV rms approx.)

Max Conductor size 0.9” (23mm)

Display 4-digit (9999 count) display

Sampling rate 0.4 seconds

Power supply One 9V battery

Power consumption 40mA

Temp. Coefficient 0.15 times the specified accuracy per degree

centigrade (from 39 to 64ºF (4 to 18oC) and 82 to

122ºF (28 to 50oC))

Current Overload Protected to 100A Continuous; 200A for less than 60

seconds (50/60Hz)

Continuity check Audible tone if reading is less than approx. 40Ω

Range selection Automatic ranging

Safety Meets the requirements for IEC1010-1 Category III 300V

and Category II 600 V

Operating conditions 4 to 122oF (-20 to 50oC) with < 85% RH

Storage conditions -20 to 140oF (-28 to 60oC) with < 75% RH

Dimensions 10.2 x 4.4 x 1.9” (258 x 110 x 47mm)

Weight 24.7oz (700g)

Accessories Resistance check plate, 9V battery, carrying case

Ground Resistance (Autorange) Specifications

Range Resolution Accuracy (of reading)

0.03 to 9.99Ω0.02 Ω ± (1.5% + 0.1 Ω)

10.0 to 99.9 Ω 0.1 Ω ± (2.0% + 0.3 Ω)

100.0 to 199.9 Ω 0.4 Ω ± (3.0% + 1 Ω) typical

200.0 to 399.9 Ω 2 Ω ± (5.0% + 5 Ω) typical

400.0 to 599.9 Ω 5 Ω ± (10% + 10 Ω) typical

600.0 to 999.9 Ω 10 Ω Not specified

1000 to 1500 Ω 30 Ω Not specified

Accuracy Note: Loop resistance non-inductive, external field < 50A/m, external electrical

field <1 V/m, conductor centered

382356 V2.0 5/03

Ground / Leakage mA Current Specifications

Range Accuracy (% of reading)

0.200 to 0.999mA ± (2.5% ± 0.05mA)

1.00 to 9.99mA ± (2.5% ± 0.05mA)

10.0 to 99.99mA ± (2.0% ± 0.3mA)

100.0 to 750.0mA ± (2.5% ± 3mA)

(Autorange, 50/60Hz, True RMS, Crest Factor <3.0)

Ground/Leakage A Current Specifications

Range Accuracy (% of reading)

0.20 to 15A ±(2.0% ±0.05A)

Max Current 100A Continuous; 200A for less than 60 seconds

(50/60Hz, True RMS, Crest Factor <2.0)

382356 V2.0 5/03

Operating Instructions

Note: The accuracy of measured readings will be affected if the clamp jaws are not fully

closed. Pay special attention to ensure that the jaws are fully closed before testing

begins.

Note: DO NOT clamp on to any conductor or open the clamp jaws during the start-up

self-calibration (display counts down from CAL 7 to CAL 0).

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. Snap the Jaws open and closed a

few times so that they seat

properly.

3. Turn the meter on by moving the

rotary switch to the ohms Ω

position. DO NOT interrupt the

start up procedure by opening the

clamp jaws or clamping around a

conductor.

4. Once the start-up calibration

procedure is completed, clamp on

to an electrode or ground rod and

read the value of ground

resistance on the display.

Continuity Loop Test

The testing procedures are the same as for

Ground Resistance measurements except that the

rotary switch is set to the •))) position and an

audible tone will sound if the measured resistance

is below approximately 40Ω.

Ground / Leakage Current Measurement

1. Turn the meter on by moving the rotary switch to

the mA or Aposition.

2. Clamp on to the electrode or conductor

3. Read the value of leakage current displayed on

the display.

RLOOP

Typical application

382356 V2.0 5/03

Principle of Operation

Typical multi-grounded distribution system.

If the parallel ground resistances,

R1, R2, R3,etc, up to Rnare combined

as Req, then only Rgand Req are

left in the circuit

If a constant voltage is applied to the circuit, the following equation applies:

eqg RR

V+= where: ni

eq ,...2,1,

∑

If Rgand R1, R2, R3…Rn, are approximately the same, and n is large (200, for example),

then Req will be much less then Rgand may possibly approach zero.

Example:

If Rgand R1, R2, R3…Rnare all 10Ωrespectively and n = 200, then Req by calculation

equals:

Ω=

=05.0

...

Rn R

Req

382356 V2.0 5/03

geqg RRR

V→=+=+= 05.1005.010

382356 V2.0 5/03

Applications

Telephone/Electrical Ground Rods

1. Remove any protective coverings from the ground conductor

2. Turn the meter to the Ohm Ωfunction.

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 note the reading.

Cellular Transmission Towers

WARNING: Use extreme care when making measurements around transmission towers.

High Voltage may be present.

The ground conductor should be located at the base of the tower, but your configuration

may be different.

1. Locate the ground conductor

2. Clamp around the ground conductor. You should place the clamp before any

splices, bonds or other splits in the ground system.

3. Read the measured reading.

Transmission

Tower

Primary

Ground Conductor

Branch

Ground Conductors

Cement Pad

382356 V2.0 5/03

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