TN-C-S (PME) Earthing
Combined PEN conductor in the supply, separated at the cut-out.
● Line● Neutral● Earth
Tap any wire, switch or device to see what it is.
Useful Information
The most common UK supply. N and E combined in the supply, split at the service head.
Important to know
- Typical maximum Ze 0.35 Ω.
- Main bonding min 10 mm² for most domestic supplies (Table 54.8).
- Lost PEN risk — special measures for EV charging and outdoor equipment (722.411.4.1).
BS 7671:2018+A4:2026 references
411.4544.1.1Table 54.8722.411.4.1
Study notes paraphrased — check against your copy of BS 7671.