If the switch box has no neutral there are four routes: use modules designed to work without neutral, such as Shelly 1L, 2L or some dimmers; add a bypass when the LED load is small; pull a neutral wire through the existing conduit if there is room; or fit the module in the junction box or next to the light fitting, where there is a neutral.
Why the neutral is missing
In a classic installation, the live runs down to the switch and back to the lamp; the neutral goes straight from the junction box to the light fitting and never reaches the switch. A normal switch does not need it, but most smart modules do, because they must stay powered while the light is off.
Options
| Option | Advantages | Bear in mind |
|---|---|---|
| No-neutral module (Shelly 1L, 2L) | Fits in the same box, no building work. | Lighting only, with a minimum load. |
| Dimmer that can run without neutral | Dims without rewiring. | Some features, such as metering, are limited. |
| Bypass at the light fitting | Prevents flicker with small LED loads. | Wired in parallel with the lamp. |
| Pull a neutral through the conduit | Lets you use any module. | Only if the conduit has room and is in good condition. |
| Module in the junction box | Live and neutral are usually there. | The box must be accessible and have space. |
Flicker and lights that do not fully switch off
A no-neutral module powers itself by passing a tiny current through the lamp. With low-power LED bulbs, that current can cause a faint glow or flicker when off. A bypass solves it by giving that current another path.
How we solve it on the visit
- We open the boxes to see which wires reach each one and their condition.
- We check for a neutral in the room’s junction box and whether the conduit has room.
- We measure or calculate the load on each lighting circuit.
- We propose the right model for each point, with or without neutral.