Fluke 381 User manual

PN 3538357
July 2010
© 2010 Fluke Corporation. All rights reserved. Printed in China. Specifications are subject to
change without notice. All product names are trademarks of their respective companies.
381
Remote Display
True-rms
Clamp Meter
Users Manual

LIMITED WARRANTY AND LIMITATION OF LIABILITY
This Fluke product will be free from defects in material and workmanship for three years from the
date of purchase. This warranty does not cover fuses, disposable batteries, or damage from
accident, neglect, misuse, alteration, contamination, or abnormal conditions of operation or
handling. Resellers are not authorized to extend any other warranty on Fluke’s behalf. To obtain
service during the warranty period, contact your nearest Fluke authorized service center to obtain
return authorization information, then send the product to that Service Center with a description of
the problem.
THIS WARRANTY IS YOUR ONLY REMEDY. NO OTHER WARRANTIES, SUCH AS FITNESS
FOR A PARTICULAR PURPOSE, ARE EXPRESSED OR IMPLIED. FLUKE IS NOT LIABLE
FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES,
ARISING FROM ANY CAUSE OR THEORY. Since some states or countries do not allow the
exclusion or limitation of an implied warranty or of incidental or consequential damages, this
limitation of liability may not apply to you.
Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands
11/99

i
Table of Contents
Title Page
Introduction................................................................................................................. 1
How to Contact Fluke ................................................................................................. 1
Safety Information ...................................................................................................... 2
Radio Frequency Data ............................................................................................... 7
Features ..................................................................................................................... 8
Remote Display ...................................................................................................... 8
Hazardous Voltage Indicator .................................................................................. 10
Flexible Current Probe ........................................................................................... 10
Auto Power Off ....................................................................................................... 10
Backlight................................................................................................................. 11
Display Hold ........................................................................................................... 11
MIN MAX AVG ....................................................................................................... 11
DC Current Zero..................................................................................................... 11
Inrush ..................................................................................................................... 12
Low Battery Indicators............................................................................................ 12

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Display.................................................................................................................... 17
Measurements............................................................................................................ 19
AC and DC Current (Jaw) ...................................................................................... 19
AC Current (Flexible Current Probe)...................................................................... 22
AC and DC Voltage ................................................................................................ 23
Resistance/Continuity............................................................................................. 26
Inrush Current Measurement (Jaw and Flexible Current Probe) ........................... 26
Frequency Measurement (Jaw and Flexible Current Probe) ................................. 28
Maintenance............................................................................................................... 28
Cleaning the Meter and Flexible Current Probe..................................................... 28
Battery Replacement.............................................................................................. 29
User-Replaceable Parts ............................................................................................. 31
Specifications ............................................................................................................. 32
Electrical Specifications.......................................................................................... 32
Mechanical Specifications...................................................................................... 37
Environmental Specifications ................................................................................. 38

1
Introduction
XWWarning
Read "Safety Information" before you use the Meter.
The Fluke 381 is a handheld, battery-operated Clamp Meter (the Meter) that has a remote-display
module and detachable iFlex (Flexible Current Probe). The Remote Display can be removed from
the Meter body and read away from the measurement source. This lets the display be easily read
in difficult-measurement situations such as a hazardous environments, or very tight spaces. The
Flexible Current Probe makes it possible to measure higher current (up to 2500 A ac) and larger
cables that traditional jawed meters cannot measure.
How to Contact Fluke
To contact Fluke, call one of the following telephone numbers:
•Technical Support USA: 1-800-44-FLUKE (1-800-443-5853)
•Calibration/Repair USA: 1-888-99-FLUKE (1-888-993-5853)
•Canada: 1-800-36-FLUKE (1-800-363-5853)
•Europe: [phone]
•Japan: [phone]

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•Singapore: [phone]
•Anywhere in the world: [phone]
Or, visit Fluke's website at www.fluke.com.
To register your product, visit http://register.fluke.com.
To see, print, or download the latest manual supplement, visit
http://us.fluke.com/usen/support/manuals.
Safety Information
A Warning identifies conditions and actions that pose hazard(s) to the user; A Caution identifies
conditions and procedures that could cause Meter damage, equipment under test damage, or
permanent loss of data.
Symbols used on the Meter and in this manual are explained in Table 1.
XWWarning
To prevent possible electrical shock or personal injury, follow these guidelines:
•Use the Meter only as specified in this manual or the protection provided by the
Meter can be compromised.
•Examine the case before you use the Meter. Look for cracks or missing plastic.
Carefully look at the insulation around the connectors.
•Never measure ac current while the test leads are inserted into the input jacks.
•Make sure the battery door is closed and latched before operating the Meter.
•Remove the test leads from the Meter before the battery door is opened.

Remote Display True-rms Clamp Meter
Safety Information
3
•Examine the test leads for damaged insulation or exposed metal. Check test lead
continuity. Replace damaged test leads before using the Meter.
•Do not use the Meter if it operates incorrectly. Protection can be compromised.
When in doubt, have the Meter serviced.
•Do not use the Meter around explosive gas, vapor or in damp or wet
environments.
•Use only type AAA batteries, properly installed in the Meter case, to power the
Meter.
•To avoid false readings that can lead to electrical shock and injury, replace the
batteries as soon as the low battery indicator (Bor Q)
appears.
•When servicing the Meter, use only specified replacement parts. See Table 5.
•Have the Meter serviced only by qualified service personnel.
•Be careful around voltages > 30 V ac rms, 42 V ac peak, or 60 V dc. Such
voltages pose a shock hazard.
•Do not apply more than the rated voltage, as marked on the Meter, between the
terminals or between any terminal and earth ground.
•When using the probes, keep fingers behind the finger guards on the probes.
•Connect the common test lead before connecting the live test lead. When
disconnecting test leads, disconnect the live test lead first.
•Do not work alone so assistance can be rendered in an emergency.

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Users Manual
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•Use extreme caution when working around bare conductors or bus bars. Contact
with the conductor could result in electric shock.
•Adhere to local and national safety codes. Individual protective equipment must
be used to prevent shock and arc blast injury where hazardous live conductors
are exposed.
•When measuring, keep fingers behind the Tactile Barrier. See Figure 2.
•Disconnect circuit power and discharge all high-voltage capacitors before you
do diode tests or measure resistance, continuity, or capacitance.
•Do not measure ac/dc current in circuits carrying more than 1000 V or 1000 A
with the Meter Jaw.
•Never operate the Meter with the back cover removed or the case open.
•Do not measure ac current in circuits carrying more than 1000 V or 2500 A with
the Flexible Current Probe.
•Do not apply the Flexible Current Probe around or remove from HAZARDOUS
LIVE conductors.
•Take special care during fitting and removal of the Flexible Current Probe. De-
energize the installation under test or wear suitable protective clothing.
WCaution
To avoid possible damage to the Meter or to equipment under test:
•Use the proper jacks, function, and range for the measurement application.

Remote Display True-rms Clamp Meter
Safety Information
5
Table 1. Symbols
Symbol Meaning Symbol Meaning
BAC (Alternating Current) JEarth ground
FDC (Direct Current) PAC and dc current.
XHazardous voltage PConforms to European Union
directives.
WRisk of Danger. Important
information. See Manual. )Conforms to relevant North American Safety Standards.
BBattery. Low battery when shown. TDouble insulated
~Do not dispose of this product as unsorted municipal waste. Go to Fluke’s website for
recycling information.

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Symbol Meaning Symbol Meaning
CAT III
IEC Measurement Category III
CAT III equipment has protection
against transients in equipment in
fixed-equipment installations, such
as distribution panels, feeders and
short branch circuits, and lighting
systems in large buildings.
CAT IV
IEC Measurement Category IV
CAT IV equipment has protection
against transients from the primary
supply level, such as an electricity
Meter or an overhead or underground
utility service.
®Examined and licensed by TÜV
Product Services. ;Conforms to relevant Australian standards.
-Do not apply to or remove from
HAZARDOUS LIVE conductors. ,Application around and removal from
HAZARDOUS LIVE conductors is
permitted.
Note
The Measurement Category (CAT) and voltage rating of any combination of test probe,
test probe accessory, current clamp accessory, and the Meter is the LOWEST rating of
any individual component.