Underground Cable FPIs

Fault Passage Indicators for Underground Cable Systems

Cable fault detection

Our FPIs for underground HV cable networks provide versatile, fully configurable, overcurrent and earth fault detection. We offer options for both communicating and local earth fault indication.


Visibility of fault passage enables the control room to identify the faulty section of network and coordinate local switching to isolate the fault and restore supplies to customers more quickly.


FPIs are offered with range of power supply options to suit your application. Our battery powered FPIs provide up to 15 years of maintenance-free operation, or for more data-intense applications, power can be sourced from the substations auxiliary AC or DC supply.

Control room visibility

Our NX-series of devices offers built-in RTU functionality and 4G communications (with 2G failover). The NX-series can deliver a native DNP3 link direct to the control room as well as over-the-air firmware updates and configuration management from iHost™.


With options for directional (using available voltage input terminals on the switchgear) or non-directional fault passage indication, load current monitoring, power flow detection, twin earth fault indication, USB and Bluetooth local communications, and much more, the NX-series is a key component of your network monitoring system.

Local fault indication

Our F-series devices offer core fault passage functionality and is the FPI of choice for many utilities. Designed to be installed at switching points on the distribution network, local indication is provided via hyper-bright LEDs. The devices can also be connected to a local distribution automation RTU via the output contact, to alert the control room to fault events on the network.


Our F-series products are compatible with 1A secondary CTs as well as our flexible retrofit CT solutions. They can be offered as a directional FPI, subject to suitable voltage input terminals on the switchgear.

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