Smart switch not working (no neutral at the switch)
A smart/Wi-Fi switch won't power up, drops offline, or makes the light glow/flicker — commonly because there's no neutral at the switch, which many smart switches need.
Safety first
Isolate and prove dead before working at the switch. Identifying conductors at a switch (loop wiring) needs care — don't assume which is which.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Apprentice mode
Full walk-through — the why, what readings mean, mistakes & safety.
Likely causes
Ranked from most to least likely.
- 1
No neutral at the switch (loop-at-light wiring)
Most likelyTraditional switch wiring loops at the light, so the switch has only switch wires — many smart switches need a neutral to power their electronics.
- 2
Smart switch needs no-neutral mode / bypass not fitted
#2Some no-neutral smart switches need a bypass device at the light, or a minimum load, to work without flicker.
- 3
Incompatible LED load
#3A tiny LED load below the switch's needs causes flicker/glow on no-neutral types.
- 4
Wiring / configuration error
Least likelyThe switch is miswired or not set up for the wiring present.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
On the tools? Job Mode shows one test at a time with thumb-sized buttons — your place and readings carry straight over.
Enter Job ModeIsolate, prove dead, and determine whether a neutral is present at the switch.
Clarity on whether a neutral exists at the switch.
Neutral present — wire/configure the smart switch normally.
No neutral — use a no-neutral-rated switch (and bypass if needed).
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Smart switch not working
→ step 2 - 2decision
Is a neutral present at the switch?
Yes→ step 3No→ step 4 - 3result
Wire/configure the smart switch normally.
- 4decision
Is a no-neutral switch used with the required bypass/load?
Yes→ step 5No→ step 6 - 5result
Re-test for flicker/glow.
- 6result
Use a no-neutral-rated switch and add bypass / suitable load.
Common mistakes apprentices make
- Fitting a neutral-required smart switch where there's no neutral.
- Skipping the bypass device a no-neutral switch needs.
- Putting a tiny LED load on a no-neutral switch and getting flicker/glow.
- Guessing conductor identity at a looped switch.
When to stop & escalate
Installing/wiring switches is licensed electrical work. Where no neutral exists, a licensed electrician selects a suitable no-neutral switch and bypass, or runs a neutral.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
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Related faults
LED lights glowing faintly when switched off
LED lamps glow dimly or pulse even after the switch is off — unsettling but usually a small leakage/induced-voltage effect rather than a dangerous fault.
A single light not working
One light fitting is dead while the rest of the lights on the circuit work fine — points at the lamp, the fitting, or the switch for that point rather than the whole circuit.
Lights flickering
One or more lights flicker — constantly, intermittently, or when other appliances run. Common with LEDs and dimmers, but can also signal a loose connection.
Learn the theory
How the gear and circuits behind this fault actually work.