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Wiring a 12 V LED to 220 V: the mistake-free guide

This article is also available in French: Brancher led 12v sur 220v

29/09/2026 · 10 min read · By the Designix team

A 12 V module is never wired directly to 220 V. You need a 220/12 V transformer in between, rated to cover the total power of the modules to be supplied. Add up the watts of the strip or spots, keep a margin, connect the primary to the mains and the secondary to the low voltage side.

Is it possible to wire a 12 V LED to 220 V?

Yes, provided you go through a 220/12 V transformer. The module stays supplied at 12 V DC, the mains voltage is stepped down and then rectified. Wired directly to a 230 V socket, a 12 V module is destroyed instantly, and no warranty claim will hold.

This is the principle behind every off-the-shelf light fitting: an LED light fitting sold ready to install already contains its 230 V to 12 V driver. The Luminaire Led collection lists 18,269 references as of 28 September 2026, a figure taken from the shop counter.

Why a 12 V module burns out on 220 V

The applied voltage is more than eighteen times what the junction can withstand. The destruction is immediate, and nothing really warns you.

Voltage multiplied: the ratio between 230 V and 12 V is around 19, the chip cannot take it
Short circuit: the junction melts, the track opens, the strip goes dark
No driver: without stepping down and rectifying, no stable current arrives
Warranty void: a setup outside the recommendations is never covered

How an LED works, and why voltage matters

An LED is a diode. It lights in one direction only and at a given voltage. Below that, nothing happens; above it, the junction heats up and then breaks. The full mechanism is described in our article on how an LED works.

A 12 V module therefore expects stabilised DC, not 230 V AC. A 24 V setup carries half the current in the strip, which limits heating on long runs.

To place the connection within the wider installation, our guide to wiring an LED to 220 V covers what happens at the consumer unit.

12 V, 24 V or 230 V fitting: which setup for which use?

	12 V LED strip	24 V LED strip	230 V LED fitting
What you need in between	A 220 → 12 V transformer	A 220 → 24 V transformer	Nothing, the driver is built in
What happens if wired directly to 220 V	The module burns out on power-up	The module burns out on power-up	Normal operation
Behaviour on a long run	Marked voltage drop, you need to re-feed	Slower voltage drop, the run holds further	Not applicable
Where it is used	Under-cabinet, alcove, display case	Ceiling and continuous runs	Pendant, ceiling light, wall light
Dimming	Dimmable power supply required	Dimmable power supply required	Depends on the bulb or driver
Access to wiring	Low voltage after the transformer	Low voltage after the transformer	Mains, must be isolated at the breaker

How do you wire a 12 V LED to 220 V?

Switch off the power at the breaker, identify live and neutral, size the transformer to the total power, then connect the primary at 230 V and the secondary at 12 V. Seven steps are enough, all carried out with the power off and a multimeter in hand.

If you are starting from a new installation, our guide to wiring an LED at home covers the basics before you move on to low voltage.

Switch off the breaker and check there is no voltage with a multimeter before any work.
Identify the conductors: live, neutral and earth. Only live and neutral feed the transformer.
Add up the power: length of strip or number of spots, in watts, then add at least 20%.
Choose the unit whose rated power exceeds that total, with a 12 V DC output.
Connect the primary to the mains, on the terminals marked L and N.
Connect the secondary to the strip or spot, respecting plus and minus polarity.
Check the output with a multimeter before powering back up: 12 V DC expected.

Wiring diagram for a 12 V LED on 220 V

The diagram fits on one line: breaker, transformer, strip or spot. Nothing else goes between them.

Which transformer for a 12 V LED?

Take a transformer whose rated power exceeds the total watts to be supplied by at least 20%, with a 12 V DC output. Five metres of strip at 8 W per metre therefore need 48 W, so a 60 W unit.

Power: the total plus 20%, never the other way round
Output: 12 V DC, not to be confused with an AC halogen transformer
Location: ventilated area, reachable for replacement

Replacing old lighting often changes the power supply as much as the fitting: our guide to replacing a fluorescent tube with an LED tube shows what that means on the driver side.

Socket, switch or fixed connection

Option	When to choose it	What to watch
Socket	Moveable string lights or fitting	The unit must stay accessible
Switch	Everyday lighting in a living room	Switching on the 230 V side, before the transformer
Fixed connection	Strip on a ceiling, in an alcove or under a cabinet	Junction box recommended for maintenance

On a fixed circuit, the connection is often made without the original connector. The technique is described in our guide to connecting an LED strip without a connector.

The rest comes down to the space left for the unit: it heats up, it needs to breathe, and it must stay reachable for the day it has to be replaced.

Nothing forces you to wire it yourself. A pendant light in 230 V arrives with its power supply and is installed like any other light point.

If the connection makes you uneasy, describe your strip and your room through our page to ask our team: we will tell you which transformer to take and which cable size, without selling you one module too many.

LED fittings ready to wire, room by room

See the whole selection: Luminaire Led

Can you cut an LED strip?

Yes, only on the cut marks printed every three LEDs. Cutting elsewhere breaks the copper track and switches off the whole downstream section. Locate the dotted line and the centre pad, then cut cleanly with a craft knife, strip laid flat.

The marks are printed at regular intervals. Each one marks the end of a group of three LEDs and its resistor.

Where to cut, and where never to cut

Printed mark: the only place where the strip cuts cleanly
Middle of a group: never, the track opens and the downstream section goes dark
End of the strip: bare pad for soldering or clipping on a connector
Bent or crushed area: avoid, the copper cracks

When the remaining length does not work out, it is better to rethink the layout than to bodge the strip: our article on installing an LED strip on the ceiling shows how to line up the cuts on corners.

What happens if you cut in the wrong place

The downstream section goes dark at once, while the upstream part keeps working. No reliable repair exists on a cut track: the strip must be replaced, not glued back together.

For those who prefer to avoid the craft knife, ready-to-install fittings are reviewed by buyers, and those reviews remain available on the Google listing for Designix.

How do you wire an LED strip to a switch?

Switch the power on the 230 V side, before the transformer. The wall switch then controls the whole unit, and the low voltage side is never live when the room is off. A switch placed after the unit requires a model designed for direct current.

Switch on 220 V or on low voltage?

230 V remains the simplest and most durable solution. Switching on 12 V is only justified when the transformer must stay powered permanently, for example in a setup in series with detection.

On the 230 V side: a standard wall switch controls the whole setup
On the 12 V side: possible, but the model must accept direct current and higher currents
Dimmer: only if the unit is stated to be dimmable

Several points on the same control are wired on the same logic as wiring spots in series, with a single feed to the power supply.

The most common case is the worktop. Our article on the LED strip under a kitchen cabinet details the cable routing and the position of the unit.

And for outdoor string lights?

Outdoor string lights are wired like a strip, with two extra requirements: the power supply must stay out of water, and the protection rating of the string lights must match the use. In our survey of 250 references in the Luminaire Led collection as of 28 September 2026, IP65 is declared on only 4% of the survey, and IP44 on 2%. In other words, weatherproofing is chosen, not assumed. Our selection of LED string lights groups the models intended for outdoor use.

For a living room, a fixed light point remains simpler than string lights: a kitchen fitting or a wall light connects directly to the mains, with no transformer to fit.

Where is your 12 V LED strip or module going?

Wiring 12 V to 220 V: the questions that keep coming up

Is it possible to wire a 12 V lamp to a 220 V circuit?

No, not directly. A 12 V lamp needs a power supply that steps 220 V down to 12 V: a 220/12 V transformer or driver placed between the socket and the lamp. Without it, the module receives a voltage nearly twenty times too high and burns out on power-up.

What happens if you connect an LED directly to a 12 V DC power supply?

That is the normal setup for a 12 V strip: it lights up, provided you respect the polarity and do not exceed the current the power supply can deliver. A module designed for a lower voltage needs a limiting resistor, otherwise it heats up and degrades.

How can I wire an LED to a 220 volt circuit?

You place a 220/12 V transformer in between, identify the two low voltage wires of the module, connect them the right way round, then feed the transformer from the 220 V circuit with the breaker off. The module never sees the mains.

Which transformer for a 12 V LED?

A transformer with a 12 V DC output, whose rated power exceeds the total of the modules to be supplied, and dimmable if you want to adjust the brightness. Check the output voltage, the power and the dimmer compatibility before buying.

Which resistor to power an LED at 12 V?

None on a strip or module sold for 12 V: the limiting resistors are already built into the product and the transformer regulates the supply. A resistor is only calculated for a bare LED, from its voltage and the target current.