TN-S Earthing
Separate neutral and earth all the way from the source — earth via cable sheath.
● Line● Neutral● Earth
Tap any wire, switch or device to see what it is.
Useful Information
Separate N and PE from the transformer. Earth is provided by the DNO via the cable sheath.
Important to know
- Typical maximum Ze 0.8 Ω (DNO declared).
- Main bonding sized to Table 54.8 / 544.1.1.
- Older lead-sheathed supplies — check the earth clamp condition.
BS 7671:2018+A4:2026 references
312.2.1.1411.4544.1.1
Study notes paraphrased — check against your copy of BS 7671.