_trad-de-v1

Wiring lights in series: the guide that avoids the mistake

This article is also available in French: Brancher lumiere en serie

29/09/2026 · 9 min read · By the Designix team

Connect each light point in parallel: live, neutral and earth continue on to the next luminaire without ever passing through the first. At 230 V, series wiring does not exist in homes. It only applies to 12 V LED strips and transformer-fed string lights. Everything else is wired in parallel.

Should lights be wired in series or in parallel?

In parallel. Each luminaire receives the full 230 V and lights up on its own. In series, the voltage is shared between the loads: two points wired that way each receive 115 V and no longer light properly. No home is wired any way other than in parallel, except for very specific uses.

Wiring a light in parallel: how a house is wired

Three conductors arrive at the point, three leave for the next one. The first luminaire never feeds the second: the line passes through it.

Live on the L terminal of the socket, switched by the light switch
Neutral on the N terminal, never switched
Earth on the metal body when it is conductive
Loop out to the next point, made inside the box and not inside the socket

This is the wiring that lets you renovate the lighting in your living room without running a separate circuit for each wall light.

What series wiring changes about brightness

Light output drops with the square of the voltage received. At 115 V, a bulb designed for 230 V delivers about a quarter of its flux, and its colour shifts. An LED module with a driver often does not light up at all.

The point-by-point details are in our article on wiring spotlights in parallel.

Series or parallel: what each wiring method changes in the room

	Series wiring	Parallel wiring
Voltage received per bulb	A fraction of the 230 V (about 115 V for two)	230 V for each bulb
If one bulb blows	The whole circuit goes out	The others stay lit
Brightness obtained	Low and uneven	Normal at each point
Number of luminaires	Limited by the available voltage	Depends on the total load of the circuit
Where it is the right solution	12 V LED strip, transformer-fed string lights	All lighting circuits in a home
Dimmer	Acts on the whole set, never bulb by bulb	Possible if the bulbs are dimmable

The luminaire changes nothing about the wiring diagram, but everything about the atmosphere: how the points are laid out shapes the room as much as the models chosen.

How do you wire lights in series?

You connect the output of one luminaire to the input of the next: the same current flows through the whole chain, and the voltage is divided by the number of loads. This wiring only makes sense at low voltage, with a transformer sized for the number of points.

Wiring 2 bulbs in series

Two identical bulbs share the voltage in two equal parts. The return wire of the first becomes the supply for the second: nothing else to add, and that is precisely the problem.

Wiring 3 luminaires in series, then 4: where it breaks down

Each additional point takes its share. Beyond three, the remaining voltage no longer properly starts a filament.

Points in series	Voltage per point	Result
2 points	115 V	Dim light, shifted colour
3 points	76 V	Barely perceptible lighting
4 points	57 V	No start on LED, filament glowing red

On low-voltage strip, the logic reverses and the sections are connected in parallel along the transformer. The principle is covered in our page on wiring a spotlight in series.

Can the bulbs of a ceiling light be wired in series?

No, and nothing requires it. A ceiling light with several sockets is already wired in parallel internally: each socket receives 230 V from a common terminal block. Wiring it in series would switch off half the fixture and halve the available light.

Ceiling light with several sockets: the internal parallel wiring

The terminal block distributes live, neutral and sometimes earth to each socket. In a review of 250 product listings in our catalogue as of 29 September 2026, 31% state an E27 base: that many fixtures designed for this parallel connection. The 2-year warranty is stated on 100% of those same 250 listings.

The material diffuses as much as the wiring: a glass luminaire spreads light on all sides, with no hot spot on the ceiling.

What a connection on a DCL box requires

The connection goes through a ceiling-mounted connection box with marked terminals.

Live on the marked terminal, switched by the light switch
Neutral on the centre terminal
Earth on the green terminal, connected to the body of the fixture
Fixing on the box screws, with the breaker off

The steps are described in detail in our guide to installing a pendant light on a DCL box.

Once the terminal is identified, the pendant light goes up in a few minutes, with no work on the ceiling.

How do you wire several lights on a single electrical supply?

You loop out from the junction box or from the switch, never from the socket. Each new point receives the same voltage as the first, and the whole set stays on one circuit as long as the combined load stays within the breaker limits.

How do you loop out from a switch?

Looping out from a switch means running wires from its terminals to a second light point controlled by the same two-way switch. Both lights then come on together, with no second switch.

The step-by-step is in our article on wiring several lights to one switch.

Looping out from a junction box: the clean method

The clean method goes through the box: you open the line there, add a run to the new point, and each conductor stays accessible for future troubleshooting. Nothing is connected inside a wall without a box.

The number of runs depends on the box volume and the conductor cross-section. Our article on wiring several lights on a single electrical supply details the diagram.

Across a whole house, each point is fitted without mixing up the series: the Alternative Laurie Lumière collection has 21057 references as of 29 September 2026. The Designix professional spaces gather requests from installers looking for a whole room set.

Wiring a bulb in series with a two-way switch: why it does not work

A two-way switch switches the live between two traveller wires. If you insert a luminaire into one of these traveller wires instead of running back to the neutral, the bulb only lights up in one position out of two. Series wiring with a two-way switch does not work.

If the diagram is clear but the choice of luminaires is still open, send us your plan: the team will guide you to the models suited to each point, through our contact page.

Luminaires designed for parallel wiring

See the whole selection: Alternative Laurie Lumière: your new lighting destination | Designix

LED, strips and transformers: the only real case for series

Series only appears at low voltage, inside a strip or a string light fed by a transformer. The diodes there are connected end to end on the same section, and the transformer provides the reduced voltage. At 230 V, each luminaire stays in parallel.

Wiring an LED on 220 V

A diode does not withstand the 230 V of the mains: it needs a driver, or a module that already has one. In the review of 250 product listings in our catalogue as of 29 September 2026, 82% mention LED technology, so the conversion is already done inside the fixture.

In the same review, 94% state an IP20 rating: suitable for dry indoor use, to be kept to rooms without water splashes.

Connecting a 12 V strip and its transformer

The strip is cut to length, connected to the secondary of the transformer, and each section stays in parallel. The transformer output must cover the total length installed.

Connecting to the secondary is detailed in our guide to wiring an LED transformer.

Joining without an original connector is explained in the article on connecting an LED strip without a connector.

What type of luminaire do you want to connect to this circuit?

Your questions about series wiring

How do you wire lights in series?

You connect the output of one bulb to the input of the next, in a loop, on a single conductor. At 230 V, this loop shares the voltage between the bulbs: two bulbs then receive only about 115 V each and light dimly. Series is therefore only justified on low-voltage equipment designed for it, such as a 12 V LED strip with its transformer.

Should lights be wired in series or in parallel?

In parallel, that is, with a loop out. Each luminaire receives 230 V, keeps its rated current, and the other points stay lit if one of them blows. This is how every lighting circuit in a home is wired, and the only method that properly accepts a dimmer.

Can the bulbs of a ceiling light be wired in series?

No, unless the fixture is designed for it. A ceiling light with several sockets is wired in parallel internally: each socket receives 230 V. Wiring it in series between luminaires would bring down the whole circuit as soon as one bulb fails.

How do you loop out from a switch?

You run wires from the terminal block to a junction box, then from the box to each luminaire, because that is where live, neutral and earth are available. The looping out is done with the power off, using accessible, marked terminals, never with a simple twisted joint.

Can a socket and a light be wired on the same electrical circuit?

No. A lighting circuit and a socket circuit are protected differently and are not mixed. A dedicated circuit is kept for lighting, which avoids plunging the room into darkness at the slightest overload on a socket.