LED strips: guide to selection, voltage and power supply

LED strips come in many variants: COB or SMD, 12, 24 or 48 volts, white or coloured, for indoors or outdoors. This guide explains what matters and how to calculate the right power supply. You will find all strips in the category LED strips.

COB or SMD – what is the difference?

• SMD strips have individual LEDs at regular intervals. They are versatile, very efficient and available in all colours. Without a diffuser the light points are visible. To the category SMD strips.
• COB strips (chip on board) have the LEDs placed so closely together that a continuous light line without visible dots is created. Ideal for flat profiles, open niches and anywhere you look directly at the strip. To the category COB strips.

Rule of thumb: where the strip is visible or the profile is very flat, COB. Where it is hidden or high output is required, SMD.

12 V, 24 V or 48 V?

• 24 V is the standard for most applications. At 24 V, depending on the wattage, usually around 5 m per feed are possible without the brightness visibly decreasing at the end. The exact length is stated in the data sheet.
• 48 V is suitable for long light lines. The 48 V Long-Run LED strip manages up to 10 m per feed, the S-COB infinicut also up to 10 m.
• 12 V is mainly used for short runs and existing 12 V installations.

Which wattage and colour temperature?

• Accent light in furniture and niches: 5–10 W/m is enough, e.g. LED strip 4.8 W/m or COB 7 W/m.
• Indirect room lighting from a cove or ceiling joint: 14–20 W/m, e.g. LED strip 14.4 W/m or 18 W/m.
• High ceilings and main lighting: up to 32 W/m with the high-output strip – only in an aluminium profile with sufficient cooling.
• Colour temperature: 2700–3000 K feels warm and homely, 4000 K neutral and matter-of-fact. Tunable White is adjustable, Dim-to-Warm becomes warmer when dimmed, like an incandescent bulb. Coloured accents can be achieved with RGBW.

Protection rating: IP20, IP65, IP67

• IP20: for dry indoor rooms.
• IP65/IP66: for bathrooms, kitchens and sheltered outdoor areas, e.g. IP65 Nano or IP66 Nano Special.
• IP67: for outdoors and façades, e.g. Neon COBPlus IP67 or neon flex.

Calculating the power supply correctly

This is how you find the right wattage: wattage per metre × length × 1.2. The 20% reserve protects the power supply and extends its service life.

Example: 5 m of LED strip with 14.4 W/m give 72 W. With a 20% reserve that is around 86 W – a 24 V / 90 W power supply fits. The voltage of strip and power supply must match. If the light is to be dimmable, choose a dimmable power supply or a controller, for example with DALI or Casambi. All models under Power supplies & drivers.

Installation tips

• Always stick the strip into an aluminium profile, especially from 10 W/m – this extends the service life.
• Only cut at the marked cutting points. The S-COB infinicut can be cut at any point.
• For connections without soldering there is the SAL solder-free LED strip, for tight curves the BEND strip.
• For long lines, feed from both sides or in the middle.

LED strips made to measure and for projects

In the LED configurator you put together strip, profile and length and receive a bill of materials and a quote. For electrical installers and planners we advise on the selection, calculate the power supplies and offer project prices. Delivery throughout Switzerland from Zurich. Get in touch.

Matching product categories

• SMD LED strips – bright LED strips in many colour temperatures
• COB LED strips – dot-free light line
• LED neon flex – flexible light lines, also for outdoors
• Aluminium LED profiles – for heat dissipation and clean light lines
• LED power supplies and controllers – 24 V and 48 V, dimmable with DALI and Casambi

LED strip with profile and power supply made to measure: LED configurator.

Frequently asked questions

What is the difference between SMD and COB?

SMD strips have individual LED chips with visible light points, are very bright and available in many colours. COB strips have LEDs placed so closely together that a continuous light line without dots is created.

How do I calculate the power supply for an LED strip?

Wattage per metre × length, plus around 20% reserve. For 5 m with 14.4 W/m that is 72 W, i.e. a power supply with 90 W. The voltage of strip and power supply must match.

How long can an LED strip be in one piece?

For 24 V strips, depending on the type, 3 to 15 m per feed. For longer lines, 48 V strips are suitable, as they allow longer runs from one side. The maximum length is always stated in the data sheet.

Can I shorten LED strips?

Yes, at the marked cutting points. The distance between the cutting points depends on the strip and is stated in the data sheet.

Which LED strip is suitable for bathrooms or outdoors?

For damp rooms and outdoors, choose strips with protection rating IP65 to IP67 or neon flex with IP67.

More guides: Choosing the right LED profile · LED panels for the office