• Ground-fault monitor for grounded and high-resistance-grounded AC systems
  • Modular installation using a single external current transformer
  • RMS measurements
  • Digital display with real-time readings
  • Configurable Form-C (SPDT) contact outputs

The RCM420 monitors for ground-fault current in solidly-grounded and high-resistance-grounded AC (single-phase or three-phase) systems. The pickup value is adjustable from 10 mA to 10 A. A separately configurable prewarning alarm is also available. Three separately adjustable time delays are available - a pickup delay, startup delay, and delay on reset.

The RCM420 provides an accurate, RMS value. Measurements are displayed in real-time via the device's on-board digital display. All device settings are configured using the display and push buttons. Two Form-C (SPDT) relay outputs are separately configurable to trigger on the pre-warning or main alarm.

A single current transformer connects to the RCM420 for measuring ground-fault current. A wide range of sizes, shapes, and core types are available.

  • Features
  • Applications
  • Accessories
  • Ordering information
  • Downloads
  • Ground fault monitoring for solidly-grounded and high-resistance-grounded AC systems
  • Meets or exceeds code requirements for ground-fault detection on grounded AC systems, where applicable
  • RMS measurement values
  • Digital display showing measured ground-fault current in real-time
  • Adjustable pickup value from 10 mA to 10 A
  • Connects to a single current transformer, available in a wide range of sizes, shapes, and core types
  • On-board test and reset buttons with connections for external activation
  • Adjustable time delays (pickup, startup, on reset)
  • Latching or non-latching operation
  • Two Form-C (SPDT) alarm outputs, operating normally energized (failsafe) or de-energized (non-failsafe)
  • Ground fault monitoring on grounded and high-resistance grounded AC systems
  • General power distribution
  • Motors and motor control centers
  • Generators, portable and fixed
  • Control systems
  • Heat trace systems, per NEC 427.22 and CEC 62-116


Mandatory accessories for LINETRAXX® RCM420

AC current transformers
Part No.OpeningShape and TypeOrdering No.
CTAC200.78" (20mm)circular, solidB98110005
CTAC351.35" (35mm)circular, solidB98110007
CTAC602.4" (60mm)circular, solidB98110017
CTAC1204.7" (120mm)circular, solidB98110019
CTAC2108.25" (210mm)circular,solidB98110020
WR70x175S2.75"x6.9" (70x175mm)rectangular, solidB911738
WR115x305S4.5"x12" (115x305mm)rectangular, solidB911739
WR150x350S5.9"x13.8" (150x350mm)rectangular, solidB911740
WR200x500S7.9"x19.7" (200x500mm)rectangular, solidB911763
WS20x300.75"x1.2" (20x30mm)rectangular, split-coreB98080601
WS50x802"x3.1" (50x80mm)rectangular, split-coreB98080603
WS80x1203.1"x4.7" (80x120mm)rectangular, split-coreB98080606

Variants of LINETRAXX® RCM420

Part No.Supply VoltageOrdering No.
RCM420-D-116-72 VAC (42-460 Hz), 9.6-94 VDCB94014001
RCM420-D-270-300 VAC (42-460 Hz), 70-300 VDCB94014002

Downloads for LINETRAXX® RCM420



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