Fluke 378 FC Non-Contact True-RMS Clamp Meter with PQ Power Quality Screening

Troubleshooting of industrial control, motors and inverter power distribution, plus harmonic screening and three-phase testing. It shares identical hardware with the 377 FC, while the 378 FC exclusively features PQ power quality indication.

Core Technology: FieldSense™ Electric Field Sensing Technology. No physical contact between the clamp jaw and live conductors. Simply connect a ground lead to measure voltage and current simultaneously, greatly reducing electric shock risks.

Key Specifications

Safety Rating: CAT III 1000 V / CAT IV 600 V

Clamp Jaw AC Current: 0～999.9 A, resolution 0.1 A; accuracy 2% ±5 digits (45–66 Hz)

iFlex Flexible Probe (Standard i2500-18, 1.8 m): AC 0～2500 A, ideal for busbars, compact switchgear and large cables

DC Voltage: 0～1000 V; AC Voltage: 0～1000 V (direct probe measurement); FieldSense non-contact voltage up to 1000 V

Frequency Range: 5 Hz～500 Hz, compatible with inverters, variable-speed motors and UPS systems

Resistance: 60 kΩ; Capacitance: 1000 μF; Continuity beep; Inrush startup current capture, MIN/MAX/Average value recording

True-RMS (TRMS) measurement, designed for non-linear loads such as inverters, servo drives and switching power supplies

Jaw Opening: 34 mm; Net Weight: 463 g; Power Supply: 2×AA batteries, battery life 200 hours

Wireless Connectivity: Fluke Connect Bluetooth. Save data, perform automatic three-phase calculations, phase sequence verification and cloud storage via mobile APP

Exclusive Functions (Difference from 377 FC)

✅ PQ Power Quality Indicator: Automatically detects voltage, current and power factor anomalies under FieldSense mode. Quickly identify whether the fault originates from upstream grid supply or downstream motor/inverter loads (early warning for harmonics, three-phase imbalance and poor power factor)

✅ Automatic Three-Phase Test: Complete three-phase measurement in 3 steps. The APP automatically calculates line-to-ground, line-to-line voltages, phase sequence and unbalance without manual recording and calculation

✅ Inrush Startup Current: Capture the closing surge current of motors and compressors to diagnose mechanical jamming and faulty starting circuits

Standard Accessories

Fluke 378 FC Clamp Meter Main Unit

i2500-18 iFlex Flexible Current Probe (1.8 m)

TL224 Test Leads, TP175 TwistGuard Test Probes, AC285 Grounding Clip (required for FieldSense function)

TPAK Magnetic Hanging Kit, Hard Carrying Case, User Manual

Model Comparison & Selection Guide

377 FC: Equipped with FieldSense, without PQ power quality screening, focused on safe and fast voltage & current measurement

378 FC: With PQ harmonic & energy efficiency screening, the top choice for maintenance of inverters, air compressors and fans

376 FC: Traditional clamp meter, no FieldSense non-contact voltage function, voltage measurement only via test probes

Order Number: 5111812 (FLUKE-378 FC)

Typical Applications (Automation / HVAC / Low-Voltage Assemblies)

Harmonic and three-phase current imbalance screening for inverter and servo drive outputs

Measurement of startup current and locked-rotor diagnosis for three-phase motors, air compressors, water pumps and fans

High-current testing on low-voltage switchgear, busbars and large cables (2500 A via iFlex probe)

Predictive maintenance, power quality pre-screening and fault location (grid side vs equipment side)

Commissioning and phase sequence verification for star-delta and soft-start circuits

Limitations & Notes

FieldSense mode requires reliable grounding. Poor grounding will cause inaccurate voltage readings; only works on single-phase conductors
The PQ function is only a screening indicator, providing pass/alarm alerts only. It cannot replace professional power quality analyzers (Fluke 43B / 437-II) for detailed THD harmonic reports
The iFlex flexible probe has a higher minimum measuring current and is not suitable for measuring tens of milliamps small currents
FieldSense cannot be used for DC voltage measurement

Upgrade & Alternative Options

Brand Upgrade: Fluke 43B / 437-II Power Quality Analyzer (for detailed harmonic analysis and waveform recording)

Domestic Equivalent: High-end clamp meters with flexible probes, Bluetooth and harmonic screening (note: no FieldSense non-contact voltage function)

Spare Parts: Separate i2500-18 probe, TP175 test probes, AC285 grounding clip

Fluke 378FC / 377FC / 376FC Note

For detailed harmonic reports, fine harmonic waveform recording and transient disturbance testing, you need professional instruments such as the Fluke 43B / 437-II.

If you frequently maintain inverters, three-phase motors and water chillers, and require safe non-contact measurement plus fast power quality troubleshooting, choose the 378 FC. If you only need non-contact measurement without PQ screening, select the 377 FC.

FC = Fluke Connect Bluetooth wireless for mobile APP data logging; non-FC models are wired-only versions.

Full Model List (Fluke Clamp Meters)

Industrial High-End Series (370 Series, TRMS AC/DC + iFlex high-current)

Non-Contact Voltage Models (FieldSense for safer cabinet testing)

377 FC: Non-contact voltage & current measurement, no PQ harmonic screening

378 FC (your model): 377 FC plus PQ power quality harmonic screening, preferred for inverters & motors

Standard Wireless Models (No Non-Contact Voltage)

374 FC: 600 A AC/DC, supports iFlex (flexible probe not included)

375 FC: Built-in VFD low-pass filter for more accurate inverter measurement (no iFlex included)

376 FC: 1000 A AC/DC, standard with i2500 iFlex probe, max 2500 A AC

Remote Detachable Display

381: Separable display for one-person operation in high-altitude and tight spaces, standard with iFlex

Industry-Specific Models
HVAC Special: 902 FC

For refrigeration, fans and heat pumps, with temperature measurement, CAT IV 300 V rating

PV New Energy Special: 393 FC

CAT III 1500 V DC rating, designed for PV string DC testing

Leakage Current Meters (Ground Leakage & Neutral Harmonic Current)

368 / 369 FC: Large jaw micro-amp leakage clamp meters, used for equipment earth leakage and neutral line current testing

Detachable Jaw for Tight Wiring Harnesses: 365

Separate jaw via flexible cable to access dense wiring; 200 A AC/DC true-RMS

General Economy Models (Daily Electrician Inspection)
Ultra-Thin Blade Jaw (narrow wiring): 301A/301C (AC only), 301D/301E (AC+DC)
High Current for Automotive & Power Systems: 317, 319 (1000 A AC/DC TRMS)
Heavy-Duty High-Current Industrial Models: 353, 355 (2000 A, for transformers and busbars)
Complete Full Model List

370 Industrial Series

373, 374, 374FC, 375, 375FC, 376, 376FC, 377FC, 378FC, 381

Small Jaw / Split Jaw Models

362, 365

Leakage Current Clamps

368, 369FC

Ultra-Thin Blade Series

301A, 301B, 301C, 301D, 301E, 302+, 303, 305

General AC/DC Models

312, 317, 319

Heavy-Duty High-Current Models

353, 355