SIN119 Surveys

The challenge

Thanks in part due to a huge rise in cable theft, traditional signalling power supplies have become increasingly vulnerable to attack, with significant amounts of copper being stolen from location cases, compromising earthing apparatus in the process.

In response to the increased risk of electrocution to both rail workers and the public, therefore, Network Rail developed SIN119 (or Special Inspection Notice 119), designed to identify any signalling location cases that do not meet target earth values.

The solution

Hitting site in March 2021 and working directly for Network Rail, Amaro was tasked with carrying out in-depth surveys of hundreds of location cases throughout the South of England, measuring them against target earth values, before comparing them against the requirements of Network Rail standards NR/L3/SIGELP/27420 and NR/L2/SIGELP/27418 as well as both IP2X and IP4X.

Only those FSPs (functional supply points) meeting the following requirements were deemed to be compliant:

• The FSP was suitably connected to an appropriate earth mat or rod
• The size/condition of the earth cable between the case and earth rod or mat was suitably sized and rated to achieve the necessary target earth resistance value
• The resistance to earth of the earth rod or mat was compliant with the NR standards outlined above
• Equipotential bonding existed within the existing case
• There were no live 650v exposed components

OR

• The existing equipment in the case was already Class II rated

With any faults or areas for improvement highlighted, remedial works could then take place, whether at the time of inspection or at a later date. Any cases that did not comply and were unable to be brought into compliance without reasonable remedial works (such as the installation of additional earth rods), were then scheduled to be upgraded to a Class II installation through the installation of state-of-the-art double-insulated switch gear and transformers.

The outcome

Spanning just over two years and completed ahead of programme, Amaro’s involvement in the SIN119 framework proved a huge success, eliciting extremely positive feedback from the client’s project management team, and further cementing the firm’s position and reputation in this field.