If you work in the rail industry and are looking for innovative ways to reduce your maintenance costs and eliminate service affecting failures caused by theft, vandalism or general degradation of signalling power cables you have arrived in the right place.

How To Use This Resource.

Max Nodder, Co-Founder and Director at Viper Innovations, gives a brief overview of the purpose of this site and how to use the resources contained within it.



CABLEGUARDIAN is an award winning product developed by VIPER INNOVATIONS, which brings together insulation resistance monitoring and conductor monitoring technologies into a single platform to enable continuous monitoring, fault diagnosis and location on live electrical systems.

Within this site you will find an array of different resources, each designed to give some background and hopefully answer the important questions you have about the product.

Please take the time to work through the various chapters and if you still have some unanswered questions then feel free to use the ‘ask an engineer button’, where your questions will be answered by one of our CableGuardian Engineers.


With the increasing age of many signalling power cables failures are becoming more of an issue for asset managers. Instances of cable theft and vandalism are also on the rise. In all cases the affected cable sections are generally difficult to identify. Faults need to be traced by personnel walking the line which takes time and resources and results in long delays for passengers.

Basic insulation monitoring already exists in signalling power supply systems in order to comply with BS7671 (IET Wiring Regulations) however the Network Rail Insulation Monitoring and Fault Location Systems for Use on Signalling Power Systems standard NR/L2/SIGELP/27725 has been introduced which recommends how monitoring can be improved. The standard considers monitoring at a network level (Tier 3), feeder level (Tier 2) and sub-network cable section level (Tier 1).


Network Rail standard NR/L2/SIGELP/50000 has been introduced which requires periodic testing to be carried out on all cables within the signalling power supply system. Complying with this standard poses significant challenges for signalling power system asset managers, including the recruitment and training of many additional electrical technicians when this skillset is in short supply and scheduling enough posessions to down-power the cables to execute the tests without interupting train services, particularly on the busiest routes.

A periodic manual cable testing regime also has the following drawbacks:

  • It requires the cables to be disconnected during the tests which risks introducing faults when the cables are re-connected.
  • It tests the cables but not the other circuit components such as transformers, connectors, switches, bus bars, which may also have insulation faults that remain undisclosed.
  • The tests only capture the cable integrity at a single moment in time, with no continuous monitoring.

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Introducing CableGuardian.