Fluke 374 FC, 376 FC-NIST, 374 FC-NIST, 376 FC User manual

374 FC/375 FC/376 FC

Clamp Meters

Users Manual

September 2015 Rev. 2, 4/20

© 2015-2020 Fluke Corporation. All rights reserved. Specifications are subject to change without notice.
All product names are trademarks of their respective companies.

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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.

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Table of Contents

Title Page

Introduction ................................................................................................................. 1

Contact Fluke ............................................................................................................. 2

Safety Information ...................................................................................................... 3

Replacement Part List ................................................................................................ 9

The Product ................................................................................................................ 10

Specifications ............................................................................................................. 22

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Introduction

The Fluke 374 FC/375 FC/376 FC (the Product) measures true-rms ac current and voltage, dc
current and voltage, inrush current, resistance, and capacitance. The 375 FC and 376 FC also
measure frequency and dc millivolts. The detachable iFlex (Flexible Current Probe) that is
included with the 376 FC (optional with the 374 FC and 375 FC) 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 FC.

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Clamp Meters

Safety Information

Safety Information

A Warning identifies conditions and procedures that are dangerous to the user. A Caution
identifies conditions and procedures that can cause damage to the Product or the equipment
under test.

Symbols used on the Product and in this manual are explained in Table 1.

Warning

To prevent possible electrical shock, fire, or personal injury:

• Carefully read all instructions.

• Read all safety information before you use the Product.

• Use the Product only as specified, or the protection supplied by the Product can

be compromised.

• Do not use the Product around explosive gas, vapor, or in damp or wet
environments.

• Do not use and disable the Product if it is damaged.

• Do not use the Product if it operates incorrectly.

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374 FC/375 FC/376 FC

Users Manual

• Prior to use, ensure the Product is clean, dry, and in good repair. Do not use the
product if has been exposed to water, cleaning solutions, battery electrolyte
leakage, or other contaminants that may have entered the enclosure. These
contaminants can reduce or eliminate the protection provided by the Product
against electric shock or arc explosion. Have the product dried, cleaned, or
repaired as necessary to ensure continued safe operation

• Use only correct measurement category (CAT), voltage, and amperage rated
probes, test leads, and adapters for the measurement.

• Do not exceed the Measurement Category (CAT) rating of the lowest rated
individual component of a Product, probe, or accessory.

• Comply with local and national safety codes. Use personal protective equipment
(approved rubber gloves, face protection, and flame-resistant clothes) to prevent
shock and arc blast injury where hazardous live conductors are exposed.

• Before each use, examine the Product. Look for cracks or missing pieces of the
clamp housing or output cable insulation. Also look for loose or weakened
components. Carefully examine the insulation around the jaws.

• Do not use test leads if they are damaged. Examine the test leads for damaged
insulation and measure a known voltage.

• Do not touch voltages >30 V ac rms, 42 V ac peak, or 60 V dc.

• Do not measure current while the test leads are in the input jacks.

• Do not apply more than the rated voltage, between the terminals or between each

terminal and earth ground.

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Clamp Meters

Safety Information

• De-energize the circuit or wear personal protective equipment in compliance with
local requirements before you apply or remove the Flexible Current Probe.

• Measure a known voltage first to make sure that the Product operates correctly.

• Limit operation to the specified measurement category, voltage, or amperage

ratings.

• The battery door must be closed and locked before you operate the Product.

• Remove all probes, test leads, and accessories before the battery door is

opened.

• Keep fingers behind the finger guards on the probes.

• Hold the Product behind the tactile barrier.

• Replace the batteries when the low battery indicator shows to prevent incorrect

measurements.

• Do not use the HOLD function to measure unknown potentials. When HOLD is
turned on, the display does not change when a different potential is measured.

• Disconnect power and discharge all high-voltage capacitors before you measure
resistance, continuity, capacitance, or a diode junction.

• Remove the input signals before you clean the Product.

• Use only specified replacement parts.

5

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374 FC/375 FC/376 FC

Users Manual

• When batteries are changed, ensure that the calibration seal in the battery
compartment is not damaged. If damaged, the Product may not be safe to use.
Return the Product to Fluke for replacement of the seal.

• Do not use in CAT III or CAT IV environments without the protective cap of test
probe. The protective cap decreases the exposed probe metal <4mm. This
decreases the possibility of arc flash from short circuits.

• Do not place magnet inside Category IV panel. Place it outside the panel instead.

For safe operation and maintenance of the Product:

• Repair the Product before use if the battery leaks.

• Have an approved technician repair the Product.

Caution

To avoid possible damage to the Product 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.

Note

The Measurement Category (CAT) and voltage rating of any combination of test
probe, test probe accessory, current clamp accessory, and the Product is the
LOWEST rating of any individual component.

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Application around and removal from

permitted.

Do not apply to or remove from HAZARDOUS LIVE conductors. Do not apply around

protective measures.

Safety Information

Table 1. Symbols

Symbol Description Symbol Description

 AC (Alternating Current)  Earth

 DC (Direct Current) 

Conforms to European Union



directives.

 Consult user documentation. 

Double Insulated



WARNING. HAZARDOUS VOLTAGE.
Risk of electric shock.

 WARNING. RISK OF DANGER.

Battery. Low battery when shown on
display.

uninsulated hazardous live conductors is



Conforms to relevant Australian



EMC standards.

or remove from uninsulated hazardous live conductors without taking additional



Certified by CSA Group to North



American safety standards.

7

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374 FC/375 FC/376 FC

Measurement Category II is applicable to test and measuring circuits connected

MAINS installation.

Users Manual

Table 2. Symbols (Cont.)

Symbol Meaning









8

directly to utilization points (socket outlets and similar points) of the low-voltage

Measurement Category III is applicable to test and measuring circuits connected to
the distribution part of the building’s low-voltage MAINS installation.

Measurement Category IV is applicable to test and measuring circuits connected at
the source of the building’s low-voltage MAINS installation.

This product complies with the WEEE Directive marking requirements. The affixed
label indicates that you must not discard this electrical/electronic product in domestic
household waste. Product Category: With reference to the equipment types in the
WEEE Directive Annex I, this product is classed as category 9 "Monitoring and
Control Instrumentation" product. Do not dispose of this product as unsorted
municipal waste.

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Clamp Meters

Replacement Part List

Replacement Part List

Table 3 lists the available replacement parts.

Table 3. Replacement Parts

Item Qty. Fluke Part or Model Number

Battery, AA 1.5 V 2 376756

Battery Door Assembly 1 4696918

Test lead set 1 TL75

Flexible current probe i2500-10 1 3676410

Flexible current probe i2500-18 1 3798105

Magnet strap 1 669952

STRAP 9 INCHES 1 669960

Soft Case 1 3752958

9

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374 FC/375 FC/376 FC

1

Clamp Meter

Users Manual

The Product

10

fig01.emf

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Clamp Meters

20

ON

ON

Auto Power Off

Backlight

The Product

fig02_3.emf

11

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374 FC/375 FC/376 FC

Display Hold MIN MAX AVG

1x

=

2x

=

3x

=

2 sec = Exit

Users Manual

12

fig04_5.emf

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Clamp Meters

2 sec = LOG

5 sec

+ ON +

x1 x2

LOG

(375 FC and 376 FC)

Clear Memory

(375 FC and 376 FC)

The Product

fig_16.emf

13

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374 FC/375 FC/376 FC

6

Flexible Current Probe

<0.5 A

>0.5 A

Users Manual

14

fig06.emf

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Clamp Meters

7

Jaw

Hz (375 FC & 376 FC)

> 5 A

> 20 A

<0.5 A >0.5 A

The Product

fig07.emf

15

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374 FC/375 FC/376 FC

<0.5 A

>0.5 A

Users Manual

16

Fig08.emf

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Clamp Meters

mV dc

(375 FC & 376 FC)

The Product

fig09_10.emf

17

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374 FC/375 FC/376 FC

<30

ON

Users Manual

18

e

R

Fig15.emf

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Clamp Meters

On

100 ms

14

Of

f

1

4

2

3

The Product

fig13_14.emf

19

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374 FC/375 FC/376 FC

1

2

3

Users Manual

20

fig11_12.emf

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Clamp Meters

2

3

5

6

CAPTURE

Connect

4

1

Fluke ConnectTM Bluetooth® Connection to FCTools

The Product

21

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374 FC/375 FC/376 FC

Users Manual

Specifications

Maximum voltage between

any Terminal and Earth Ground ............. 1000 V

Batteries .................................................. 2 AA, NEDA 15A, IEC LR6

Operating Temperature ........................... -10 °C to +50 °C

Storage Temperature .............................. -40 °C to +60 °C

Operating Humidity ................................. Non condensing (< 10°C)

≤90 % RH (at 10 °C to 30 °C)
≤75 % RH (at 30 °C to 40 °C)
≤45 % RH (at 40 °C to 50 °C)

Operating Altitude ................................... 2000 m

Storage Altitude ...................................... 12 000 m

Size (L x W x H) ..................................... 249 mm x 85 mm x 45 mm

Weight ..................................................... 410 g

Jaw Opening ........................................... 34 mm

Flexible Current Probe Diameter ............ 7.5 mm

Flexible Current Probe Cable Length

(head to electronics connector) .............. 1.8 m

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Clamp Meters

Specifications

Safety ...................................................... IEC 61010-1, Pollution Degree 2

IEC 61010-2-032: CAT III 1000V / CAT IV 600V

IEC 61010-2-033: CAT III 1000V / CAT IV 600V

Ingress Protection (IP) Rating ................. IEC 60529: IP30

Radio Frequency Certification ................. FCC ID:T68-FBLE IC:6627A-FBLE

Wireless Radio Frequency Range .......... 2412 MHz to 2462 MHz

Output Power .......................................... <100 mW

Electromagnetic Compatibility (EMC)

International IEC 61326-1: Portable, Electromagnetic Environment, IEC 61326-2-2

CISPR 11: Group 1, Class A

Group 1: Equipment has intentionally generated and/or uses
conductively-coupled radio frequency energy that is necessary for the
internal function of the equipment itself.

Class A: Equipment is suitable for use in all establishments other
than domestic and those directly connected to a low-voltage power
supply network that supplies buildings used for domestic purposes.
There may be potential difficulties in ensuring electromagnetic
compatibility in other environments due to conducted and radiated
disturbances. Emissions that exceed the levels required by CISPR 11
can occur when the equipment is connected to a test object.

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374 FC/375 FC/376 FC

Users Manual

Temperature Coefficients........................ Add 0.1 x specified accuracy for each degree C above

AC Current via Jaw

Range

374 FC and 375 FC ........................... 600.0 A

376 FC ............................................... 999.9 A

Resolution ............................................... 0.1 A

Accuracy ................................................. 2 % ±5 digits (10 Hz to 100 Hz)

2.5 % ±5 digits (100-500 Hz)

Crest Factor (50 Hz/60 Hz)

376 FC .............................................. 3 @ 500 A

2.5 @ 600 A

1.42 @ 1000 A

374 FC and 375 FC .......................... 2.5 @ 350 A

Note: Add 2 % for C.F. >2

24

28 °C or below 18 °C

1.42 @ 600 A

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Clamp Meters

Specifications

AC Current via Flexible Current Probe

Range .................................................... 2500 A

Resolution ............................................... 0.1 A (≤999.9 A)

1 A (≤2500 A)

Accuracy ................................................. 3 % ±5 digits (5 Hz – 500 Hz)

Crest Factor (50 Hz/60 Hz) ..................... 3.0 @ 1100 A

2.5 @ 1400 A

1.42 @ 2500 A

Add 2 % for C.F. >2

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374 FC/375 FC/376 FC

Users Manual

Position Sensitivity

26

Figure 1. Position Sensitivity

ghn12.png

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Clamp Meters

Specifications

Distance from

Optimum

A 0.5 in (12.7 mm) 1.4 in (35.6 mm) ±0.5 %

B 0.8 in (20.3 mm) 2.0 in (50.8 mm) ±1.0 %

C 1.4 in (35.6 mm) 2.5 in (63.5 mm) ±2.0 %

Measurement uncertainty assumes centralized primary conductor at optimum position, no
external electrical or magnetic field, and within operating temperature range.

DC Current

Range

374 FC and 375 FC ........................... 600.0 A

376 FC ............................................... 999.9 A

Resolution ............................................... 0.1 A

Accuracy ................................................. 2 % ±5 digits

i2500-10 Flex i2500-18 Flex Error

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374 FC/375 FC/376 FC

Users Manual

AC Voltage

Range ..................................................... 1000 V

Resolution ............................................... 0.1 V (≤600.0 V)

1 V (≤1000 V)

Accuracy ................................................. 1 % ±5 digits (20 Hz to 500 Hz)

DC Voltage

Range ..................................................... 1000 V

Resolution ............................................... 0.1 V (≤600.0 V)

1 V (≤1000 V)

Accuracy ................................................. 1 % ±5 digits

mV dc (375 FC and 376 FC)

Range ..................................................... 500.0 mV

Resolution ............................................... 0.1 mV

Accuracy ................................................. 1 % ±5 digits

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Clamp Meters

Specifications

Frequency via Jaw

Range

375 FC and 376 FC ........................... 5.0 Hz to 500.0 Hz

Resolution ............................................... 0.1 Hz

Accuracy ................................................. 0.5 % ±5 digits

Trigger Level ........................................... 5 Hz to 10 Hz, ≥10 A

10 Hz to 100 Hz, ≥5 A

100 Hz to 500 Hz, ≥10 A

Frequency via Flexible Current Probe

Range

375 FC and 376 FC ............................. 5.0 Hz to 500.0 Hz

Resolution ............................................... 0.1 Hz

Accuracy ................................................. 0.5 % ±5 digits

Trigger Level ........................................... 5 Hz to 20 Hz, ≥25 A

20 Hz to 100 Hz, ≥20 A

100 Hz to 500 Hz, ≥25 A

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374 FC/375 FC/376 FC

Users Manual

Resistance

Range

374 FC ............................................... 6000 Ω

375 FC and 376 FC ........................... 60 kΩ

Resolution

374 FC ............................................... 0.1 Ω (≤600 Ω)

1 Ω (≤6000 Ω)

375 FC and 376 FC ........................... 0.1 Ω (≤600 Ω)

1 Ω (≤6000 Ω)

10 Ω (≤60 kΩ)

Accuracy ................................................. 1 % ±5 digits

Capacitance

Range ..................................................... 1000 µF

Resolution ............................................... 0.1 µF (≤100 µF)

1 µF (≤1000 µF)

Accuracy ................................................. 1 % ±4 digits

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