Short answer
If one light flickers or buzzes, it is usually the combination of LED and dimmer. If all lights dip briefly when an appliance comes on, that is a voltage dip and usually normal. If lights throughout the house flicker irregularly for no reason, there may be a bad connection in the main supply, and that is a reason to have it looked at soon.
Who this article is for Anyone bothered by flickering or unsteady light. You can rule out the first two causes yourself.
One light flickers or buzzes
Almost always the combination of LED and dimmer. LED bulbs draw little power and old dimmers were made for incandescent bulbs of 40 watts and up. Below their minimum they become unsteady.
What helps:
- an LED dimmer suitable for small loads
- dimmable bulbs of the same brand, because different ones react differently
- sometimes an extra bulb on the same dimmer, which takes you above the minimum
If a light without a dimmer flickers, check that the bulb is properly seated in the holder and that the fitting itself is not faulty.
All lights dip briefly when something comes on
That is a voltage dip. A motor starting up, think of a pump, a compressor or an old freezer, briefly draws a lot of current. The voltage drops for a moment and you see that in the light.
As long as it is brief and coincides with an obvious appliance, that is normal, especially at the end of a long cable. If it happens with every appliance and lasts noticeably long, the cable is too light or too long.
The whole house flickers for no reason
This is the situation that matters. Possible causes:
A loose neutral. In the service head, in the meter cupboard or in a junction box. With a bad neutral connection the voltage between the phases starts to shift: on one circuit it gets too high, on another too low. Lights burn too bright or too dim, and equipment gets damaged by it.
A bad terminal in the main supply. You sometimes notice it with the weather and temperature: it gets worse when it is windy or when it is hot.
Something in the street. If the neighbours report the same, it is the grid operator.
What I do
I measure the voltage per phase under load, look at the terminals in the meter cupboard and the service head with a thermal imaging camera, and test the neutral. A warm terminal shows up on the image straight away, even if there is nothing to see with the naked eye.
With a measurement the grid operator comes quickly; without one, rarely.
If it is in the grid operator's part, I record it and report it with the measurement. That saves discussion and they then usually come out quickly.
Why you should not wait with this
With a loose neutral the voltage on a circuit can rise to well above 230 volts. Whatever is on it gets damaged, and it is exactly the kind of fault that slowly gets worse. Flickering lights throughout the house are therefore not an inconvenience but a warning sign.
From my own work
A customer in Beek had had lights flickering now and then for months, throughout the house. Two electricians had blamed the LEDs. With a thermal imaging camera I saw that the neutral terminal in the service head was warm. The grid operator renewed the terminal and the flickering stopped at once. A loose neutral is exactly the kind of fault that damages equipment.
When to call an electrician
- Lights flicker throughout the house, not in one room
- It happens more when it is windy or in warm weather
- Appliances break down for no clear reason or behave strangely
A loose neutral can wreck equipment and is no small matter. Call +31 43 204 18 26 or use the fault service.
Frequently asked questions
Is flickering light dangerous?
In a single room usually not, that is often LED with an old dimmer. If it flickers throughout the house, there may be a loose neutral, and that is a reason to have it looked at soon.
Why do the lights dim when the washing machine comes on?
That is a voltage dip: a motor briefly draws a lot of current when starting. Brief and coinciding with an appliance is normal.
Can a loose neutral wreck equipment?
Yes. The voltage on a circuit can then rise well above 230 volts, and whatever is on it gets damaged.
Further reading
RCD keeps tripping: how to find the cause yourself
Usually it is one appliance and not your installation. In four steps you find out yourself which one, and you read exactly where it stops and you need to call.
The circuit breaker trips: overload or short circuit
A breaker that only trips after a while points to overload. If it trips straight away, it is a short circuit.
Power out in one room: the step-by-step plan
One room without power is almost always one circuit. In four steps you know which one, and what to do if nothing seems to have tripped.
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