LED Strips: 12V vs 24V, IP Ratings, and Selecting Drivers and Profiles

Short Answer

Calculating the power supply is simple: multiply the strip's power per metre by the total length and add a 25–30% safety margin. For wet areas and outdoor use, an enclosed strip is required (IP65–IP68 according to EN/IEC 60529), whereas for dry indoor rooms, an open IP20 rating is sufficient. Do not adhere strips with a power rating of approximately 10 W/m to wood, plasterboard, or plastic—without an aluminium profile for heat dissipation, the LEDs will overheat and degrade many times faster than their rated lifespan.

12 V vs 24 V: What is the physical difference?

A strip of any voltage produces the same light output—the difference lies in the current flowing through its conductive tracks. Since power P = U × I, for the same 60 W load, a 12 V strip draws 5 A, while a 24 V strip draws only 2.5 A. Losses in the tracks and wiring are proportional to the square of the current (P = I²R): halving the current results in four times lower losses for the same resistance.

In practice, this manifests as a voltage drop towards the far end of the strip: the final LEDs receive fewer volts, resulting in dimmer light and a "yellowish" colour shift. With a medium-power 12 V strip, this effect becomes noticeable even on a standard five-metre reel (5000 mm is the most common length on the market), whereas a 24 V strip offers a significantly greater length margin. This is why manufacturers cut strips into specific sections and specify the maximum connection length from a single power point—always check the specifications for the specific series rather than relying on guesswork.

Parameter	12 V	24 V
Current at 60 W load	5 A	2.5 A
Track losses at equal resistance	4 times higher	Baseline
Allowable length from one power point	Shorter; brightness degrades towards the end of the reel	Longer; more uniform illumination
Cutting increments	Usually shorter (multiples of 3 LEDs)	Usually longer (multiples of 6 LEDs)
Typical application	Short sections: shelves, cabinets, local accent lighting	Ceiling niches, light lines, extended contours

48 V LED strips are a niche solution for very long continuous runs. 220–230 V strips connect to the mains via a rectifier without requiring a low-voltage power supply, but they typically have larger cutting increments and more stringent application limits when used inside furniture.

Power per metre and what it means

The product range features a power consumption spread from 1.6 to 48 W/m. The ranges can be categorised as follows:

• 4–5 W/m — subtle accent lighting: niches, shelves, and contour lighting. The most common values are 4 W/m and 4.8 W/m.
• 7–10 W/m — a versatile range for interiors: kitchen worktop lighting and cornices. Popular values include 7.2 W/m and 9.6 W/m.
• 12–15 W/m — primary lighting for light lines and niches; requires an aluminium profile for heat dissipation.
• 19–30 W/m and above — high-brightness series for general lighting; these must not be operated without an aluminium profile.

Calculating the power supply: formula and safety margin

The calculation is straightforward, with no hidden coefficients:

1. Load power = strip power (W/m) × length (m). Example: 9.6 W/m × 5 m = 48 W.
2. Power supply capacity = load power × 1.25…1.3. For the example: 48 × 1.25 = 60 W → use a 60 W power supply or higher.

A 25–30% safety margin is not just a precaution; it is required for three specific reasons: a power supply operating at its limit generates more heat and has a shorter lifespan; actual strip consumption may be a few per cent higher than the nominal rating; and start-up currents (especially for outdoor installations in cold conditions) are more demanding than nominal operation. Using a power supply that is "just enough" is a common cause of flickering and premature failure within a single season.

Next, check the current: a 24 V / 100 W power supply delivers approximately 4.2 A. The cross-section of the cables from the power supply to the strip should be selected based on this current and the run length. For long runs, use 1.5–2.5 mm² conductors to prevent voltage drop before the power reaches the strip.

If the LED strip is dimmed via a low-side controller, a standard constant voltage power supply is suitable. For systems using input-side dimming, a dedicated dimmable driver is required—please refer to the LED driver category, where you will also find IP65–IP67 rated waterproof series for outdoor use.

IP Rating: Selecting the Right Protection

IP Rating	Meaning	Application
IP20	Open PCB without enclosure	Dry rooms: niches, cornices, furniture, profiles
IP54	Protected against dust and splashes	Areas with occasional moisture
IP65/IP66	Dust-tight, protected against water jets	Bathrooms (outside direct contact zones), canopies, facades
IP67	Withstands temporary immersion	Outdoor use, areas subject to direct water contact
IP68	Continuous immersion	Fountains, swimming pools, water features

Two practical considerations: First, a sealed enclosure reduces heat dissipation; therefore, for IP65+ strips, thermal management requirements are stricter than for open strips of the same power rating. Second, the protection rating of the entire system is determined by its weakest link—an IP67 strip paired with a non-waterproof connector and an IP20 driver in a wet zone does not constitute a moisture-protected installation. For bathrooms, place the power supply outside the wet zone—electrical equipment must be installed outside areas reachable by water to comply with HD 60364 safety requirements.

Profiles: Heat Dissipation, Not Just Decoration

LED lifespan is directly affected by junction temperature: overheating accelerates phosphor degradation and causes luminous flux depreciation. An aluminium profile acts as a heatsink, drawing heat away from the strip's substrate and dissipating it. As a rule of thumb: strips up to ~10 W/m may be adhered directly to metal or mineral surfaces, but anything higher must be installed in a profile. Do not adhere medium-power strips directly to wood, MDF, or plasterboard without a profile, as these materials provide poor thermal conductivity.

How to choose a profile

• Channel width — must be wider than the strip: standard strip widths are 8–12 mm, and profiles come in dozens of sizes to accommodate various types.
• Mounting type — surface-mounted, recessed, or corner profiles, depending on the specific installation requirement.
• Diffuser type — an opal diffuser reduces some light output but completely hides the individual LED points; a clear diffuser provides maximum light output.
• Completeness — end caps and mounting clips are often sold separately; ensure you include them in your specification from the start.

Common installation errors

1. Daisy-chaining long segments. Connecting two or three reels in a single continuous line from a single power point guarantees brightness degradation towards the end and overloads the traces of the first segment, which carry the current for all subsequent segments. Correct method: provide parallel power to each segment using separate wires from the driver, or feed a long line from both ends.
2. Undersized power supply. Operating a driver at 100% of its rated capacity leads to overheating and premature failure. Maintain a safety margin of 25–30%.
3. High-power strips adhered with adhesive without a profile. Strips with power ratings of ~10 W/m or higher mounted directly onto wood or plasterboard will lose light output and undergo yellowing long before the end of their rated service life.
4. Using IP20-rated strips in damp areas. Corrosion of traces and contacts may not appear immediately, but will manifest after several months.
5. Cutting outside the designated cut lines. Strips must only be cut at the marked sections; for most items, the section length is specified in the technical characteristics in the catalogue.
6. Insufficient cross-section of supply wires. Voltage drop across thin, long wires running from the driver to the strip "consumes" brightness just as much as the length of the strip itself.

Comparison of typical strips from the catalogue

Three items illustrating the choice based on voltage and ingress protection (IP) — ranging from open interior 12 V strips to moisture-protected 12 V IP67 and 24 V IP65 versions for damp areas:

What is required for a complete kit