• 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.
W1-S351.35" (35mm)circular, solidB911731
W2-S702.75" (70mm)circular, solidB911732
W3-S1054.1" (105mm)circular, solidB911733
W4-S1405.5" (140mm)circular, solidB911734
W5-S2108.25" (210mm)circular,solidB911735
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



Category Product Language Date Size Download