You switch off the hall light and head to bed. The new LED bulb is still glowing, a faint ghost of light in the dark. Nothing is on, so what is feeding it? An LED bulb glowing when switched off is common in UK homes, and it is usually a harmless trickle of leakage current. Occasionally it is a wiring fault. This guide shows you how to tell which.

Why an LED bulb glowing after switch-off is so common

An old filament bulb needed real current to heat up, so a small leak did nothing you could see. An LED lamp and its driver react to far less. A very small leakage current can charge the driver and make the lamp glow or flash.

Leakage needs a path. Something is still linking the lamp to the live supply, or coupling to it, even with the switch off. This is 230V mains, so treat every cause below as live until the circuit is isolated at the consumer unit.

The five causes at a glance

Most glowing LEDs come from one of five causes, and most fixes are a lamp or switch swap, such as a trailing-edge LED dimmer. The table shows what each looks like and who should fix it.

Cause 1: illuminated and neon switches

An illuminated switch has a small indicator inside it, usually a neon or LED, wired across the switch contacts. With the switch off, a trickle of current passes through the indicator and on through the lamp to neutral. A halogen bulb ignored that. An LED lamp glows.

The check is simple. If the glow only appears on circuits with an indicator switch, you have found it. Replace the switch with a plain rocker plate from the light switches range. The same collection covers two-way and intermediate types if the circuit has more than one switch.

Isolate at the consumer unit first. Switching off at the wall does not make the back box safe.

Causes 2 and 3: dimmers and long cable runs

Dimmers need a little current to run their own electronics, and some pass a small amount on to the lamp even when off. Older leading-edge dimmers are the usual culprit with LEDs. A trailing-edge LED dimmer such as the BG 881 is built for low loads. The TEO listing rates it at 200W, or 100W of LED load (checked 17 October 2026). Check the lamp says dimmable too.

Cable capacitance is the quieter cause. Live and neutral conductors lying side by side act like a very small capacitor. Over a long run, enough current can couple across to make a driver glow. Two-way circuits are classic cases, because the strapping cables between the switches run the full distance.

A bleed resistor or small load across the lamp soaks up that leak. It is a job for an electrician, because the right part depends on the circuit.

Causes 4 and 5: the lamp itself and wiring faults

Some lamps glow by design or by cheap design. Smart bulbs keep a receiver powered, and low-quality drivers charge slowly and bleed through the LED. If a different brand in the same holder stays dark, the lamp is the cause. Luceco lamps are a mainstream option, with dimmable GU10s from £5.62 each (checked 17 October 2026).

How to work out which cause you have

1. Note the pattern. One fitting or several? A faint glow or a bright one?
2. Look at the switch. Does it have an indicator, or is it a dimmer?
3. Swap the lamp. Isolate at the consumer unit, then try a different brand in the same holder.
4. Move the lamp. Put the glowing lamp on a different circuit. If it still glows, the lamp is the cause.
5. Stop if it looks like a fault. Bright glow, several fittings or a live holder means call a registered electrician.

Fixes that work and what to buy

Match the lamp, the switch and the load. Capacity is rarely the problem. The type of dimmer usually is.

Worked example: a hallway with eight downlights

A hallway has eight 5W GU10 lamps on a leading-edge dimmer, and they glow at zero. The load is 8 x 5W = 40W, well inside a 100W LED rating, so capacity is fine. The dimmer type is the problem. Swap to a trailing-edge LED dimmer and fit dimmable lamps. Eight Luceco LGDW5G37 lamps at £5.62 each come to £44.96 (checked 17 October 2026).

• The lamp is marked dimmable if it goes on a dimmer.
• The dimmer is a trailing-edge LED type.
• Total lamp wattage sits inside the dimmer's LED rating.
• A plain switch replaces any indicator switch on an LED circuit.

In England, like-for-like replacement of a switch is generally outside notifiable work, while adding or altering circuits is a different matter. Approved Document P explains when to notify. Wales and Scotland have their own rules.

Mistakes that make the glow worse

• Fitting a bypass part blind. The right value depends on the circuit, so leave it to an electrician.
• Mixing dimmer and lamp types. A non-dimmable lamp on a dimmer glows, buzzes or flickers.
• Shrugging off a bright glow. A change in brightness is a reason to investigate, not ignore.
• Trusting the wall switch. Switching off at the wall does not isolate the circuit. Use the consumer unit.

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