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Throughwiring - Definition, Installation & more

Lighting with throughwiring is the term used for fixtures that can be connected in series. In this way, only one connection to the mains is required for several lightsources: The cables are fed through the housing of the fixture so that another can be installed directly behind it. Even though the principle and the implementation are simple, there are some things you need to consider when throughwiring. You can find out what these are and which products we recommend in the following blog entry.

Throughwiring with battens in an industry hallThroughwiring with battens in an industry hall

What does throughwiring mean?

As described above, "throughwiring" refers to a specific feature of a fixture. This means that you can connect the fixture to the power supply while at the same time passing it through the body from one end to the other. In this way, you can connect another fixture directly to the power supply behind the first one. If the following light sources also have the option of throughwiring, you can repeat the process several times and thus connect multiple fixtures in series. The advantage: You only need one power connection.


How to install fixtures with throughwiring?

Installing a fixture with throughwiring is not particularly complicated: Inside the housing you will usually find two luster terminals. These are connected to each other: They conduct the current to the bulbs/light modules (or previously to a driver/ballast) as well as to the other luster terminal.

Attach the fixture directly to the mains, simply connect the cables to the first terminal. The luminaire is now supplied with power and can already be operated. You can now connect more cables to the second terminal and lead them out of the fixture into another fixture. Then connect them again to the first luster terminal and so on. How many light sources you can connect in a row using throughwiring is explained below.

Enclosed you will find two pictures that illustrate how the connection of a throughwiring works. Please note here: The middle three cables that go out from the luster terminal (right picture: brown, yellow-green, blue) are intended for the mains connection. The remaining two (black, grey) are additional wires that you can use for various functions. Here it is possible, for example, to connect sensors or to connect different fixtures to each other and thus create groups that can then be controlled by switch. However, the throughwiring of the fixture also works if you only use the regular three cables for the power connection.

Second luster terminal for the throughwiringSecond luster terminal for the throughwiring
The wires are attached to the second luster terminal and led into the next fixture in the row. They are then connected to the first terminal there again.
Throughwiring via luster terminalThroughwiring via luster terminal
The first luster terminal is connected to the cables of the mains or those of the fixture in front.

Which fixtures support throughwiring?

In our shop, you can easily see which fixtures support throughwiring by looking at the title of the respective product. Here you will find the term "throughwiring". This is often followed by information about the cross-section of the respective cables: 5x2.5 mm² means that 5 cables of 2.5 mm² each are routed through the fixture.

Note: If you simply connect the fixtures to the mains via the regular three cables (brown, yellow-green, blue) and run them through the housing, this value is naturally reduced to 3x2.5 mm².

Battens with throughwiring

LED batten with throughwiring from NoxionLED batten with throughwiring from Noxion

Noxion Battens

LED batten with throughwiring from LedvanceLED batten with throughwiring from Ledvance

Ledvance Battens

LED batten with throughwiring from PhilipsLED batten with throughwiring from Philips

Philips Battens

Symbol Lampe

By the way: Theoretically, you can provide any fixture with a suitable luster terminal with throughwiring. All you have to do is drill a hole in the housing. Then connect the additional cables to the terminal and feed them through the hole into the next fixture you want to connect in series. However, we recommend that you have this done by qualified personnel to avoid mistakes and injuries.      

How many fixtures can be connected in series?

How many lamps/fixtures you can connect in a row via throughwiring depends on which circuit breaker you have installed in your fuse box and which light source you want to install. As a rule, the higher the power (wattage) and the length of the fixture, the fewer of them you can connect in series.

With the products of the Poseidon Pronox IP65 V2.0 series, this means, for example:


Circuit Breaker 600 mm 18 W 1.200 mm 30 W 1.500 mm 43W 1.500 mm 65 W + DALI
B16 80 Fixtures 60 Fixtures 45 Fixtures 29 Fixtures
C16 80 Fixtures 60 Fixtures 45 Fixtures 34 Fixtures


Battens on a ceiling of a storage hallBattens on a ceiling of a storage hall

The specific data of each fixture can be found in the data sheet. If you want to install a large number of fixtures with throughwiring, simply contact our lighting experts! They will create a customized quotation for you!

Throughwiring for damp-proof fixtures

If you would like to install a moisture-proof fixture with throughwiring in your area of application, you must first ensure that the fixture itself has a high IP protection class. IP44, for example, reliably protects against splashing water and can thus be ideally applied in areas where the bulbs come into contact with water from time to time.

If, on the other hand, you need fixtures that are to permanently withstand water and steam and can also be cleaned with a high-pressure cleaner, you should go for IP65 (protected against jet water) or IP66 (protected against strong jet water). This way, the light source is not only absolutely protected against moisture, but also against dust.


Throughwiring in a room full of washing machinesThroughwiring in a room full of washing machines

But a high IP protection class alone is not enough: once you have laid the cables, make sure that the interfaces are also watertight. The LED battens of the Poseidon series, for example, have a screw mechanism that compresses the cables with the help of a rubber ring so that no gap remains open. Comparable products of this kind usually have a similar mechanism.

If you do not want to take any risks, you should also make sure that you use cables that also have a protection class of IP65. These are usually coated with a special material and combine the different strands. In this way, you seal off the interfaces particularly well with the rubber seals and ensure that no water or dust is guaranteed to penetrate the fixture.   

Max - last Update March 2023