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/DC systems
  • Modular installation using a single external current transformer
  • Works with AC/DC power conversion equipment including variable frequency drives
  • Digital display with real-time readings
  • Configurable Form-C (SPDT) relay contacts

The RCMA420 monitors for ground-fault current in solidly-grounded and high-resistance-grounded AC/DC (single-phase or three-phase) systems. The RCMA420 is also compatible with systems that contain power conversion equipment, such as variable frequency drives and inverters.

The pickup value is adjustable from 10 mA to 500 mA (for a higher pickup value, refer to RCMA423 series). A separately configurable pre-warning alarm is also available. Three separately adjustable time delays are included - a pickup delay, startup delay, and delay on reset.

The RCMA420 provides an accurate, RMS value. Measurements are displayed in real-time via the device's on-board digital display. All device are configured using the display and push buttons. Two Form-C (SPDT) relay outputs are separately configurable to trigger on pre-warning or main alarms.

A single current transformer connects to the RCMA420 for measuring ground-fault current. A wide range of sizes are available.


  • Ground-fault monitoring for solidly-grounded and high-resistance-grounded AC/DC systems
  • Meets or exceeds code requirements for ground-fault detection on grounded AC/DC systems, where applicable
  • Works on systems with power conversion equipment, including variable frequency drives and inverters
  • RMS measurement values
  • Digital display showing measured ground-fault current in real-time
  • Adjustable pickup value from 10 to 500 mA
  • Connects to a single current transformer, available in a wide range of sizes
  • 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/DC 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
  • Battery backup systems
  • Grounded solar arrays, per NEC 690.41(B) (2017 edition), NEC 690.5 (2014 edition), and CEC 64-064(4)
  • Energy storage systems

Downloads for LINETRAXX® RCMA420

CE Declarations of Conformity RCMA42x 88.7 KB 2022/08/12 06:17:2512.08.2022 06:17:25
Manuals RCMA420 1.7 MB EN2021/05/07 10:08:2507.05.2021 10:08:25D00059
Datasheets RCMA420 326.9 KB EN2020/01/10 10:35:0210.01.2020 10:35:02D00059
Quickstarts RCMA420 1.0 MB EN2021/05/05 06:29:2505.05.2021 06:29:25D00059
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® RCMA420

Connection cable for use with RCMA420/423 and CTUB100 series current transformers

Part No.LengthOrdering No.
CTX-1003' (1m)B98110080
CTX-2508' (2.5m)B98110081
CTX-50016' (5m)B98110082
CTX-100032' (10m)B98110083

AC/DC current transformers

Part No.OpeningShape and TypeOrdering No.
CTUB101-CTBC200.78" (20mm)circular, solidB78120010
CTUB101-CTBC20P0.78" (20mm)circular, solidB78120020
CTUB101-CTBC351.35" (35mm)circular, solidB78120012
CTUB101-CTBC35P1.35" (35mm)circular, solidB78120022
CTUB101-CTBC602.4" (60mm)circular, solidB78120014
CTUB101-CTBC60P2.4" (60mm)circular, solidB78120024

For systems requiring larger sizes, refer to RCMA423 ground-fault monitor.


Part No.Supply VoltageOrdering No.
RCMA420-D-116-72 VAC (42-460 Hz), 9.6-94 VDCB94043001
RCMA420-D-270-300 VAC (42-460 Hz), 70-300 VDCB94043002