25kV Live Line Voltage Indicators | Network Rail Approved

Published 10 Sep 2020

Live Line Indicators

25kV Live Line Voltage Indicators

Network Rail | PADS Approved | PADS Number 0091/012337

Thorne & Derrick distribute a wide range of PB Weir Substation Earthing and Transmission Line Earthing Equipment: including line end clamps, earth end clamps, portable earthing leads and operating poles for high voltage substations.

The Network Rail Approved C31 Live Line voltage Indicator is designed for use upon overhead a.c. rail electrification systems operating at 25kV nominal voltage to indicate the presence of extra high voltages to aid safe working practices.

C31 Live Line Voltage Indicator Kit Includes

  • Live Line Indicator
  • HV Probe and Hook
  • 8mtr Arctic Orange 50sqmm Alufex Lead
  • J117 Rail Clamp
  • Battery Charger

Live Line Voltage Detector

C31 Live Line Indicator Kit | Network Rail Approved

Voltage Indicator PRODUCT FEATURES

  • Dual Independent Circuitry
  • Automatic Meter Prover
  • Triple Resistor Set


The 25kV Live Line Indicator incorporates a number of important safety features, including Dual Independent Circuitry. This means that the analogue meter and the LED indicators work completely independent of each other. If one circuit fails, the other will keep on working for your safety.

An Automatic ‘Meter Prover’ operates every time the tester is turned on, proving the electrical and mechanical operation of the analogue meter.

Triple Resistor Sets ensure that the remaining resistors are sufficient to safely protect the operator and the equipment, in the unlikely event of one HV resistor failing.

The resistors are tested at 40 KV AC.

The 50sqmm Aluflex grounding cable will safely conduct the full force of the OHL system in the event of a catastrophic failure of the equipment, such as direct contact with the overhead line.

Automated Test Cert Validation, warning lights flash when test certificate has expired.

C31 Live Line Indicator KitThe C31 Live Line Voltage Indicator kit comprises the following:

  • the live line indicator, which comes in a tough protective carry case
  • a high voltage probe and hook – shrouded for use in wet weather
  • an 8 metre length of 50mm2 aluflex cable with a rail clamp.
  • battery charger for charging the C31’s internal Nickel Metal Hydroxide batteries.





0-40kV ac

LED change over

11kV ± 500V

Test duration

<25kV 10 mins > 25kV 1 min

Absolute Max. Rating

40kV ac


Analogue 2%

Analogue Op. Temp

-40c to +70c

LED Op. Temp

-10c to +50c

Seal Rating


Tester body IP65, Probe and gauge IP68

Further technical details:

  • For use upon overhead a.c rail electrification systems at 30kV nominal voltage.
  • 12kV +/- 5% Threshold voltage. Compatible with standard Westminster operating poles and Primary Insulator pole.

NEWS Thorne & Derrick | Network Rail Approved Cable Trough System Delivered to South Rail Systems Alliance

Network Rail Supplier

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& Installation Equipment

Thorne & Derrick supply an extensive range of 400V-33kV Rail Cable Accessories & Power Distribution Sytems including feeder pillars to contractors undertaking Low Voltage Power Distribution, HV Electrification & Substations, DC Traction & Networks, OLE and Track Feeder Cable Renewals – a complete range of Network Rail PADS approved track terminations, cable joints, cable repair and connection products up to 25kV, including 3M Cold Shrink, Pfisterer CONNEX and Nexans Euromold products.

Full range of Cable Pulling Equipment & Products to ensure safe and efficient of rail cables in to cable ducts and containment infrastructure including cable troughs.

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Further Reading