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.
Safety first
Even a faint glow means a small voltage is present — still isolate and prove dead before working on the fitting.
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.
Full detail — causes, the why, and common mistakes.
Likely causes
Ranked from most to least likely.
- 1
Switched neutral instead of active
Most likelyIf the switch breaks the neutral (not the active), the lamp stays at near-mains potential and can glow.
- 2
Induced voltage in long/parallel cable runs
#2Capacitive coupling in shared/long cabling induces a small voltage that lights sensitive LEDs.
- 3
Illuminated / electronic switch leakage
#3A switch with a neon/locator or an electronic (smart) switch passes a tiny standing current.
- 4
Very sensitive LED driver
Least likelySome LED drivers glow on minute leakage that wouldn't affect other lamps.
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.
Confirm the switch breaks the active (not the neutral) for that light.
The switch interrupts the active conductor.
Switching is correct — look at induced voltage / switch leakage.
Switched neutral — correct so the active is switched.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
LED glows when off
→ step 2 - 2decision
Does the switch break the active (not neutral)?
Yes→ step 3No→ step 4 - 3decision
Is there an illuminated/smart switch or long parallel runs?
Yes→ step 5No→ step 6 - 4result
Switched neutral — correct so the active is switched.
- 5result
Switch leakage / induced voltage — address the source.
- 6result
LED/driver is very sensitive — consider different lamps / a bleed device.
Common mistakes apprentices make
- Assuming it's dangerous when it's usually small leakage/induced voltage.
- Not checking whether the switch is breaking neutral instead of active.
- Overlooking an illuminated or smart switch as the leakage source.
- Working on the fitting without isolating because 'it's only a glow'.
When to stop & escalate
A switched-neutral arrangement is a wiring defect a licensed electrician should correct. If it can't be resolved with switching/source fixes, a small bleed/load device or different lamps may be the licensed electrician's remedy.
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.
Related faults
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.
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.
Learn the theory
How the gear and circuits behind this fault actually work.