Flickering LED lights can be dangerous, but not every flicker indicates danger. Sometimes, an LED might flicker because the bulb is simply defective; other times, there could be wiring issues that require a fault-finding electrician to investigate the problem and diagnose the cause. Additionally, aside from the electrical risk, the flicker itself can affect your health, with eye strain, headaches and more affecting some people.
In this guide, we explain why LED lights flicker, when that flicker is a cause for concern, the potential health risks and how you can fix the bulbs and eradicate the issue.
Flickering LED lights at a glance
| What you are seeing | Likely cause | Risk level | What to do |
| One new bulb flickering from the start | Faulty or damaged bulb | Low | Swap or return the bulb |
| Flicker only on a dimmer | Incompatible dimmer or bulb | Low-moderate | Fit an LED-compatible dimmer and dimmable bulbs |
| Lights dip when an appliance switches on | Voltage fluctuation on the circuit | Moderate | Have the circuit assessed |
| Flicker across several fittings. Buzzing or scorching evident | Wiring fault | High | Call an emergency electrician |
| Older bulbs slowly dimming and flickering | End of bulb life | Low | Replace the bulb |
Why do LED lights flicker?
LED lights can flicker for several reasons; we’ve listed them below and then explored each.
- Poor installation
- Wiring issues
- Damaged or faulty bulb
- Voltage fluctuations from large appliances
- Incompatibility with dimmer switch
Poor installation
LED lights that are not installed correctly can lead to significant problems at your property. What may start as a gentle flickering could be masking something more serious going on behind the light fitting. In the worst case, it could become a fire risk.
Whilst this could be seen as an extreme example, and perhaps rare, an improper installation could also cause your bulbs to draw more energy than they should, perform erratically and fail earlier than expected.
Wiring issues
Wiring issues are often associated with poor installation, but this isn’t always the case. Older homes with dated wiring systems could develop faults that cause LEDs to flicker. When you know the bulb has been installed correctly and works properly when tested elsewhere, yet it still flickers when you turn it on at home, it might be best to call a London electrician. They can investigate where wiring issues originate and the best course of action to stop your LEDs from flickering. Our recent guide on when to rewire a house, explains why it might be necessary to get a professional assessment.
Damaged or faulty bulb
Sometimes, it is just that the bulb is broken inside. You may not notice it when you buy it or when your handyman installs it, but within minutes of turning the light on, you do. If there are defects with your bulb, the best thing to do is take it back to where you bought it and exchange it for a new one.
Voltage fluctuations from large appliances
One of the most common and often misunderstood causes is a voltage dip on the circuit. LED bulbs draw very little power, so adding a few bulbs won’t overload the circuit, but when you use a high-demand appliance, like a washing machine, it pulls the voltage down across the whole circuit for a moment. Your LED bulbs are sensitive to this sudden change and will flicker as the appliance kicks in.
The occasional dip is normally harmless, but frequent occurrences or heavy flickering when appliances are used can indicate an overloaded circuit that needs assessment.
Incompatibility with dimmer switch
If your LEDs flicker on a dimmer, the problem is normally a mismatch between systems rather than the bulb. Most older dimmers are TRIAC types, designed for incandescent bulbs. They have a minimum load that low-watt LEDs fall below, which often causes flickering and occasional buzzing.
The solution is to ensure you use a confirmed dimmable LED bulb with a trailing-edge LED-compatible dimmer switch. Mixing new LEDs with old-era dimmers is one of the most common reasons for flickering bulbs, and it’s one of the easiest to fix.
Do all LED lights flicker?
No. A correctly installed, well-made LED on a compatible circuit shouldn’t visibly flicker at all. Flicker is mainly down to the quality of the bulb’s driver. This is the component that converts the alternating current from the home into the steady supply the LED needs. Cheaper drivers will regulate the current less smoothly, which is why budget bulbs will flicker more often than higher-quality ones.
One thing worth noting is that some flicker from LED bulbs is too fast for you to even see. UK mains run at 50Hz, and low-quality drivers can let a rapid modulation through that your eyes don’t register as flashing. However, your visual system still responds to it. It is this that can sometimes make a room feel subtly uncomfortable, even if the lights appear to be perfectly steady.
So, how dangerous are flickering LED lights?
Flickering LED bulbs can be dangerous in two ways, and we should cover both to help you reduce any risk.
Electrical danger
A flickering LED bulb caused by loose wiring, an overloaded circuit, or a failing connection is often a warning sign that something in your electrical system needs attention. Without having your wiring inspected, the problem could escalate and lead to overheating, fire or electric shock.
If you spot your LED bulbs flickering, treat it as a cause for concern if:
- The flicker occurs across several fittings or rooms rather than just one bulb
- There is a buzzing sound, burning smell, warm switches or scorch marks on and around the bulbs and switches
- The flickering occurs around other electrical problems, such as a tripping RCD
Any of these means you should contact a trusted London electrician as soon as possible rather than try to address the issues yourself.
The health danger
Flickering LEDs aren’t just an electrical concern. There are potential health issues, too. Flicker, including flickering that is too fast to see consciously, is a recognised cause of physical symptoms.
Guidance from IEEE 1789 and occupational health bodies links temporal light modulation to eye strain, headaches, tiredness, reduced concentration and migraines.
It is worth noting:
- Migraine and headache triggers: Prolonged exposure to flickering light, even when it is not obvious, can cause sensitive people to develop headaches and migraines.
- Eye strain and fatigue: Working or reading for long periods under flickering LEDs can leave you tired and unfocused without any obvious cause.
- Photosensitive seizures: For a small number of people, flickering light can be a trigger for seizures. It remains rare, but is why flicker limits exist as an engineering standard.
- Stroboscopic effect: Around moving or rotating machinery, flicker can make moving parts look like they are moving slower than they really are, or appear stopped. In a workshop or garage, for example, this can be an extreme health and safety risk.
How to fix flickering LED bulbs
Some flickering LED bulbs are a simple, quick fix; others require the expertise of a qualified electrician. Our table below shows whether it’s a DIY or an electrician job.
| Cause | How to fix | DIY or electrician |
| Faulty bulb | Test the bulb in another fitting. Return or replace if it still flickers | DIY |
| Loose bulb | Switch it off, let it cool and reseat the bulb in its socket | DIY |
| Incompatible dimmer | Fit an LED-compatible trailing-edge dimmer and confirmed dimmable bulbs | Electrician |
| Voltage dips from appliances | Have the circuit assessed and rebalanced if needed | Electrician |
| Loose or faulty wiring | Trace and repair the fault | Electrician |
| Old or degraded wiring | Inspect and, where necessary, rewire | Electrician |
As a general rule, if swapping the bulb or the dimmer doesn’t solve the problem, or if the flicker affects more than one fitting, get the wiring checked. You can book an electrician in London with us, and we’ll dispatch someone quickly to get your problem resolved.
Not sure if your flickering lights need an electrician?
A single flickering bulb is often a quick fix, but if it is happening across multiple fittings, there could be cause for concern. Homeowners and landlords should consider calling an electrician immediately so the problem can be located, fixed and made safe. Our team of qualified and experienced London electricians is available across the city with emergency call-out if required. Call 020 7186 0270 or complete an online enquiry.
