What is a screening conductor?
At a glance
An aluminium conductor run alongside telecoms cables and earthed at intervals, to reduce the voltage induced in them by AC traction.
Why: On AC electrified lines the overhead line induces voltage in long metallic cables. A screening conductor cuts that down so the cables stay within safe limits.
Where: Along copper cable routes in AC areas, with earth points at set intervals. It must never be taken into a building, cabinet or REB.
Where the rules are
- NR/GN/TEL/31106 cl 7.5.1mutual screening conductor
- NR/GN/TEL/31106 cl 7.5.2return screening conductor (RSC)
- NR/L3/TEL/30108 cl 5.3.7screening conductor must never enter a building, cabinet or REB
- NR/PS/TEL/31102 cl 1product spec for the aluminium screening conductor
- NR/GN/TEL/30139 cl 6.1surveying in AC areas — screening conductor and earth farms
On the drawing
Shown on the copper drawings with its earth points; a screening conductor schedule is produced.
- NR/GN/TEL/30139 cl 7.18screening conductor schedule
Also called: mutual screening conductor, return screening conductor, RSC, aluminium screening conductor
Guidance in our words. Read the current issue of each standard before you design to it.