Innovative technologies for safe handling of electrical power to achieve high availability

We offer you first-class quality and safety combined with global service and every support in resolving your monitoring problems.


  • 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.


  • 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

Downloads for LINETRAXX® RCM420

CE Declarations of Conformity RCM42x 89.4 KB 2022/08/12 06:17:2512.08.2022 06:17:25
Manuals RCM420 1.7 MB EN2021/03/18 13:27:0518.03.2021 13:27:05D00057
Datasheets RCM420 285.2 KB EN2020/01/10 10:35:0210.01.2020 10:35:02D00057
Quickstarts RCM420 1.0 MB EN2021/03/26 07:29:1526.03.2021 07:29:15D00057
Datasheets XM420 interface options 223.5 KB EN2019/05/13 10:31:3613.05.2019 10:31:36D00051
Technical Information Changed variants of relays from goldplated to silver-plated contacts 166.3 KB EN2022/06/27 09:03:0827.06.2022 09:03:08

Optional 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

LINETRAXX® RCM420 Variants

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