Sooner or later the question comes up with every DIY light: am I actually allowed to do this myself, or do I need an electrician? The answer is more nuanced than a flat yes or no, because it depends on which part of the installation is being worked on.
The legal basis: VDE 0100
Low-voltage installations are governed by national wiring regulations (in Germany the VDE 0100 series), along with occupational safety rules and, if something goes wrong, the question of liability. In practice, these regulations draw a clear line: the fixed electrical installation of a building – everything hard-wired behind the socket or ceiling outlet – may only be installed, altered or repaired by a qualified electrician. Everything on this side of the socket, i.e. handling finished, tested electrical equipment, is in principle allowed for anyone.
What a non-professional may do
Assembling a light from ready-made parts – lamp holder, fabric cable, ceiling rose, plug – is something you're allowed to do yourself, as long as you're working inside the light and the end result is a unit with a proper mains plug that goes into a normal socket. That applies equally to table lamps, floor lamps and plug-in pendants. Changing bulbs, replacing a faulty lamp holder on a plug-in light or rewiring an old lamp with a plug also fall into this category – details are in the article Rewiring an old lamp. The reason this is allowed: the plug is a standardised, tested point of disconnection. What happens behind it remains the responsibility of whoever uses the appliance – just as with any other household electrical appliance that you're allowed to repair yourself without being an electrician.
What a layperson must not do
The fixed connection to the household installation is the limit. As soon as a light is connected directly to the wires from the ceiling or wall – i.e. with no plug and socket in between – it counts as a change to the fixed electrical installation. That includes seemingly small jobs: rewiring a terminal block at the ceiling outlet, swapping a switch in the wall, fitting a new box. All of this belongs exclusively in the hands of a qualified electrician. How a ceiling connection like this is done properly – so you know what matters when you're watching or preparing – is described in the article Fitting a ceiling rose: ceiling connection – but it doesn't replace a qualified electrician, it only explains the process.
Liability and insurance
The practical reason for this separation isn't just the regulations themselves, but liability if something goes wrong. If a fire or personal injury is caused by a DIY change to the fixed installation, your buildings or home contents insurance may refuse to pay if it turns out no qualified electrician was involved – regardless of whether the work was objectively done properly. With a plug-in light, which is connected via a tested, standardised component (the plug), this risk doesn't apply, because you stay within the permitted use of an electrical appliance. That's also why rented flats practically never need the landlord's permission for plug-in lights, but do for a hard-wired ceiling connection.
The plug-in light as the default for non-electricians
If you're unsure or don't have access to a qualified electrician, go for a plug-in light by default: same look, same components, but a plug at the end of the cable instead of a fixed connection. That way almost any light actually intended for the ceiling can be built with a longer cable and a ceiling rose with a plug. The article Plug-in light without a ceiling connection gives an overview, and matching plugs and inline switches are under Switches and plugs.
Commercial use and rentals: separate rules
If you run lights commercially rather than privately, or install them permanently in rented properties, you are also subject to mandatory inspection requirements (in Germany under DGUV Regulation 3) and have to work with qualified electricians anyway. Information for trade customers and larger projects is available under B2B.
If you want to play it safe from the start when building a new light, choose the plug-in variant with a matching plug and sufficient cable length directly in the configurator.