Connecting work lights to a semi-trailer for more light while working

LED work lights are a smart addition to the standard semi-trailer lighting. When working on site, they can come in very handy. We explain the options available and help you get started with connecting them.

In this blog you will read:

• Tips for connecting additional work lights around the semi-trailer
• How to determine which work lights are best suited for each situation

Note: Do you use work lights as reversing lights? Then also check out our special blog on reversing lights on semi-trailers.

An LED work light on a semi-trailer is essentially an addition to the standard lighting set. The standard lighting set for a semi-trailer consists of: combination rear lights (rear light, brake light, indicator, fog light and a triangular reflector), marker lights and side marker lights.

Choosing the work light - floodlight or spotlight?

When selecting additional work lights, it is important to choose the right light image. After all, each application requires a different light distribution:

Floodlight (flood beam): Ideal for loading and unloading or lighting a large work area around the semi-trailer. Gives wide, even light.

Spotlight (directional beam): Suitable for jobs where you want to illuminate just one specific spot, such as inspection or precision work.

Good to know: work lights must not be switched on while driving on public roads. Only ECE R23-certified lights may switch on automatically when reversing.

Additional points of interest when choosing a work light

• Light output (lumen): The more lumen, the more powerful the beam. For heavy work in the dark, we recommend at least 1500 lumen.
• Beam pattern: Floodlights for wide light (loading/unloading), spotlights for focused light (specific jobs).
• Housing and IP values: A work light must be able to withstand rough handling. Choose a light with a high IP protection rating (e.g. IP67 or IP69K) for use in wet and dusty environments.
• Approved quality: Choose lights with CE marking and E-approval to ensure they are suitable for use on public roads.

Now that the application is clear, it's all about technology: can the system handle the additional lighting?

Check whether the electrical system is suitable for additional work lights

Before installing additional LED work lights on a semi-trailer, it is very important to check whether the existing electrical system can handle this load. This will prevent interference, overloading or even damage to your vehicle or semi-trailer.

Check the capacity of the lighting system:

• Note the voltage of the system (usually 12V or 24V).
• Check the fuse rating of the existing circuit (e.g. 10A or 15A).
• Calculate the total power consumption of all planned work lights: Formula: Amps = Wattage / Voltage. For example: 30W / 12V = 2.5A per light.
• Compare the consumption with the fuse value, with a margin of ±10%. Do you exceed the capacity? Consider a separate circuit with relay and fuse and connect the lights directly to the battery of the towing vehicle.

Check the semi-trailer's wiring harnesses:

• Inspect the cable insulation for damage or ageing.
• Check connectors for oxidation, play or moisture.
• Assess wire thickness: sufficient for current-carrying work lights.
• Check branch lines or extensions for watertightness.
• Are interference or flashing lighting visible? Consider a new or weighted wiring harnesses with waterproof connections.

Truck after installation:

• Check that the work lights burn steadily without flickering
• Check for fault messages on the dashboard (due to canbus)
• Measure voltage drop if necessary (use multimeter)
• Check that the lights respond correctly to switches or vehicle controls
• Truck the lights at full load (all lights on at the same time)

Connecting work lights to the semi-trailer

There are various options for connecting an LED work light to a semi-trailer. The most common connections are explained in more detail below.

Deutsch connector

The Deutsch connector is a commonly used connector when connecting the work light to a semi-trailer and are available in various lengths up to 4 metres. The advantage of a Deutsch connector is that mounting in the cable system is easy compared to other connectors.

Of course, it can happen that an LED work light on your semi-trailer gets broken. In such a case, replacing the work light is very easy. You can very easily disconnect the broken work light and replace it with a new LED work light. This is because the LED work lights feature a simple Deutsch connector.

Deutsch come in various lengths with the option of branching. This allows you to connect more work lights to your semi-trailer. It is also possible to connect a Deutsch connector to your existing cable with a connection set.

AMP Superseal connector

The AMP SuperSeal connector is a waterproof connector that can withstand harsh conditions such as exposure to fuel, oil, salt, etc. These connectors are used in many different industries, such as agriculture, the machinery sector and the automotive industry, and are therefore ideal for connecting a work light to a semi-trailer.

Make sure that the connectors are IEC529 and DIN40050 certified as waterproof.

Connection box/distribution box

The connections are linked using a junction box. A junction box can be used as a central unit in which the connections are linked. This is ideal when you want to connect work lights to a semi-trailer. A main cable runs from the towing vehicle to the distribution box, from which all the lighting on the semi-trailer is controlled.

The TRALERT® choice

If you are looking for a good work light for the semi-trailer, TRALERT® has a number of top products. These include impact-resistant and very strong lights that can take a beating.

Better Light Work Safer!

Interference on the dashboard after adding additional work lights?

You may occasionally see interference appear on the dashboard. When you connect work lights to your semi-trailer, the towing vehicle may fail to detect the LED lighting. This is because the LEDs draw too little power from the towing vehicle, meaning the vehicle fails to detect the lighting. You can read more about this in our article on resolving a canbus interference.

Tailor-made advice for vehicle manufacturers

Are you active in surface mounting, conversion or delivery of semi-trailers and looking for durable, powerful LED work lights? TRALERT® supports vehicle manufacturers with high-quality lighting and smart connection solutions.