Loop-In (3-Plate) Method
The loop-in method is the standard for modern UK lighting circuits. The supply cable runs from rose to rose, looping through each ceiling rose in turn. A separate switch cable drops from each rose to the switch.
How It Works
The Three Plates
Inside a 3-plate ceiling rose, there are three separate terminal blocks:
| Plate | Conductors | Purpose |
|---|---|---|
| Loop-in | L, N, E (from supply + loop out) | Mains connection and continuity |
| Switch | Switch live, switch return | Connection to the wall switch |
| Pendant | L to lamp, N to lamp | Feeds the light fitting |
The switch cable uses brown for switch live and blue sleeved brown for the switch return (confusingly, the return is also live when the switch is on — it must be sleeved).
Key Rules
- The mains supply loops through each rose continuously — it does not branch.
- The switch cable only carries live conductors (both cores are live at various times) — there is no neutral at the switch.
- This is why modern smart switches that require a neutral often cannot replace a standard switch on a loop-in circuit.