LED lighting in a kitchen, inside a wardrobe, below the ceiling or out on a balcony — all of it works through a transformer (power supply) that steps 230 V down to 12 or 24 V. If the transformer is fitted wrong, the strip either will not come on or it will burn out. In Ursynow and Mokotow we regularly install power supplies during kitchen and living room upgrades — clients buy the strip, and we hook everything up properly.

Caution: transformer installation means working with 230 V mains voltage. Wrong connections can lead to a short circuit, electric shock or fire. Do not wire a power supply yourself unless you really know what you are doing — call a professional.

Installation cost and what affects the price

The cost comes down to where the unit is mounted, how long the cable run is, and how the installation has to be done. If the transformer is right by a socket, the work is fast. If the cable has to be routed through a wall, into trunking or above a ceiling, it takes more time. The client buys the power supply; we wire it in and secure it safely. Fixings are included. Up-to-date prices for all electrical services are listed in the table.

How transformer installation works

1. We switch off the circuit the transformer will be connected to.
2. Pick the mounting spot — the power supply needs airflow and cannot be closed off in a space with no ventilation.
3. Fix the transformer in place: with screws, inside trunking or on a DIN rail (depending on the model).
4. Wire the 230 V input through terminals: live, neutral, earth (if included).
5. Wire the 12/24 V output to the LED strip or fittings, keeping the polarity correct.
6. Turn the breaker back on and test: the strip lights evenly and the transformer stays at a safe temperature.
7. Neaten the cables into trunking or fasten them with clips; mark the circuit if needed.

Common mistakes when installing an LED transformer

• Transformer selected with no power reserve — it overheats and packs in after a few months. Safe rule: at least 20% above the total strip wattage.
• Power supply built into a wall or boxed in without ventilation — it heats up until it cuts out or fails.
• Polarity swapped on the output — the strip does not run, or with RGB it lights the wrong way.
• Using 0.5 mm cable on a long run — voltage drops and the strip is weaker at the far end.
• Connecting more than 5 metres of strip in series — the far end overheats while the beginning shines brighter.
• Installing a non-waterproof transformer in a bathroom — moisture gets in, then short circuit.

What to prepare before the technician arrives

• Buy a transformer with the right wattage and voltage (12 V or 24 V — matching your strip).
• Decide where the power supply will be installed — close to the strip or in a separate place (consumer unit, recess, cupboard).
• If cable has to be routed — get the trunking ready or let the technician know beforehand.
• Show us where the consumer unit is and which breaker controls the lighting circuit.
• If the strip is already fixed in place — make sure its wires reach the correct point.
• Provide access details: intercom code, parking, clear route to the installation spot.
• If the lighting has several zones (kitchen + living room) — go over the layout in advance.
• Confirm whether a dimmer or controller is required — this changes the transformer choice.

A real case from Warsaw

A client in Zoliborz ordered under-cabinet LED strip lighting (24 V) for his kitchen worktop. The strip was already fixed under the wall units, but the transformer was lying loose on top of the cabinet, plugged into a standard socket. The cable was hanging down the wall. We moved the power supply into an upper cabinet with ventilation, connected it to a dedicated circuit from the consumer unit using Wago connectors and concealed the cable in plastic trunking. We also fitted a switch under the cabinet for easier use. The whole job took about an hour and a half. Now no cable is left hanging, the transformer is hidden from view, and the lighting comes on with one button (compatible with Legrand, Schneider Electric, ABB and similar).

Frequently asked questions

Book an LED transformer installation

We install transformers and LED lighting all over Warsaw. We connect, mount and test the whole setup. Get in touch — we will advise on the transformer and come out to connect it.