Extech 380260 Operating Manual

User Guide

Model 380260
Insulation Tester / Megohmmeter

Introduction

Congratulations on your purchase of Extech’s Insulation Tester/Megohmmeter. The Model
380260 provides three test ranges plus continuity and AC/DC voltage measurement. A handy
test lock feature and a data hold function are also included. This professional meter, with
proper care, will provide years of reliable service.

Safety

1. Circuits under test must be de-energized and isolated before connections are made
(except for voltage measurements).

2. Circuit connections must not be touched during a test. Use extreme caution when
working near bare conductors and bus bars. Accidental contact with conductors could
result in electrical shock.

3. Use caution when working near voltages above 60VDC or 30VACrms.

4. After insulation tests, capacitors must be discharged.

5. Test leads (including alligator clips) must be in good working order, clean and without
broken or cracked insulation.

6. When servicing, use only specified replacement parts.

International Safety Symbols

Caution, refer to this manual before using this meter

Dangerous Voltages

Meter is protected throughout by double or reinforced insulation

Meter Description

1. LCD Display

2. Hold Button

3. Test Button

4. Rotary Switch

5. Backlight Button

6. Lock Button

7. Input Terminals

2

Model 380260 Version 2.1 12/06

Operation

Warning

Ensure that the circuit under test does not include components that can be damaged by 1000VDC; such
devices include power factor correction capacitors, low voltage mineral insulated cables, electronic light
dimmers, and ballasts/starters for fluorescent lamps.

Connecting Test Leads

For all measurements, connect the red test lead to the VΩ input terminal and the black
test lead to the COM input terminal.

Test Lead Check

1. Set the rotary switch to the 200Ω range.

2. Touch the test lead tips together.

3. Resistance should read less than 0.5Ω and the audio tone should sound.

4. With the leads not touching, the display should read infinity indicated by “1”.

5. Readings displayed other than the readings described above are indicative of a test
lead problem. The test leads must be replaced before using the meter. Failure to do
so could result in damage to equipment and electrical shock.

Insulation Resistance Measurements (Megohmmeter Tests)

Warning: Do not perform Insulation Resistance measurements if AC Voltage is present on the

device under test.

1. Connect the red test lead to the VΩ input terminal; black lead to the COM terminal.

2. Set the function switch to the desired MΩ test voltage position.

3. Connect the tips of the test leads to the equipment under test. If there is a voltage
present, a constant beep will sound and the voltage will be displayed.

4. The display will show “1“ until the TEST button is pushed. Press and hold the TEST
button. The upper right display shows the test voltage applied and the flashing high

voltage symbol

5. Keep the test leads connected to the equipment under test and release the TEST
button. The circuit will discharge through the meter. Keep the test leads connected
until the circuit is completely discharged and the upper right display shows 0 volts.

will be displayed. The main display shows the resistance.

Lock Function

For hands-free operation, use the LOCK feature.

1. With the test leads connected to the equipment under test, simultaneously press the
TEST and LOCK keys.

2. The LOCK icon”
seconds to indicate that the meter is in Lock mode.

3. Press the LOCK key to disable the Lock function and end the test.

” will appear on the display. A beeper will sound every 2

3

Model 380260 Version 2.1 12/06