Fluke 374 User manual

PN 3608883
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.
374/375/376
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 ................................................................................................. 2
Safety Information ...................................................................................................... 3
The Meter ................................................................................................................... 9
Specifications ............................................................................................................. 19
Electrical Specifications.......................................................................................... 19
Mechanical Specifications ...................................................................................... 26
Environmental Specifications ................................................................................. 27

374, 375, 376
Users Manual
ii

1
Introduction
XWWarning
Read "Safety Information" before you use the Meter.
The Fluke 374, 375, and 376 (the Meter) measure true-rms ac current and voltage, dc current
and voltage, inrush current, resistance, and capacitance. The 375 and 376 also measure
frequency and dc millivolts. The detachable iFlex (Flexible Current Probe) that is included with the
376 (optional with the 374 and 375) expands the measurement range to 2500 A ac. The Flexible
Current Probe provides increased display flexibility and allows measurements of awkward sized
conductors and improved wire access. The illustrations in this manual show the 376.

374, 375, 376
Users Manual
2
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]
•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.

Clamp Meters
Safety Information
3
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 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.
•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.

374, 375, 376
Users Manual
4
•Do not use the Meter around explosive gas, vapor or in damp or wet
environments.
•Use only type AA batteries, properly installed in the Meter case, to power the
Meter.
•When measuring current with the Jaw, keep fingers behind the Tactile Barrier.
See "The Meter" .
•To avoid false readings that can lead to electrical shock and injury, replace the
batteries as soon as the low battery indicator () appears.
•When servicing the Meter, use only specified replacement parts.
•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.
•Use extreme caution when working around bare conductors or bus bars. Contact
with the conductor could result in electric shock.

Clamp Meters
Safety Information
5
•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.
•Disconnect circuit power and discharge all high-voltage capacitors before you
measure resistance, continuity, or capacitance.
•For the 374 and 375, do not measure ac/dc current in circuits carrying more than
1000 V or 600 A with the Meter Jaw.
•For the 376, 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.
•Do not use the flexible current sensor if the inner contrasting insulation color is
showing.
•Take special care during fitting and removal of the Flexible Current Probe. De-
energize the installation under test or wear suitable protective clothing.

374, 375, 376
Users Manual
6
WCaution
To avoid possible damage to the Meter or to equipment under test:
•Use the proper jacks, function, and range for the measurement application.
•Clean the case and accessories with a damp cloth and mild detergent only.
Do not use abrasives or solvents.
Table 1. Symbols
Symbol Meaning Symbol Meaning
BAC (Alternating Current) JEarth ground
FDC (Direct Current) ~
Do not dispose of this product as
unsorted municipal waste. Go to
Fluke’s website for recycling
information.
XHazardous voltage PConforms to European Union
directives.

Clamp Meters
Safety Information
7
Symbol Meaning Symbol Meaning
WRisk of Danger. Important
information. See Manual. )Conforms to relevant North American Safety Standards.
Battery. Low battery when shown
on display. TDouble insulated
®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.

374, 375, 376
Users Manual
8
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.
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.

Clamp Meters
The Meter
9
The Meter
Clamp Meter
fig01.eps

374, 375, 376
Users Manual
10
20
ON
ON
Auto Power Off Backlight
fig02_3.eps

Clamp Meters
The Meter
11
Display Hold MIN MAX AVG
1x
=
2x
=
3x
=
2 sec = Exit
fig04_5.eps

374, 375, 376
Users Manual
12
Flexible Current Probe
1
2
<0.5 A >0.5 A
3
fig06.eps

Clamp Meters
The Meter
13
Jaw Hz
(375 & 376)
1
2
> 5 A
> 20 A
<0.5 A >0.5 A
Fig07.eps

374, 375, 376
Users Manual
14
1
2
3
<0.5 A
Fig08.eps

Clamp Meters
The Meter
15
dc (375 & 376)
fig09_10.eps

374, 375, 376
Users Manual
16
eR
R
ON
e
<30
Fig15.eps