LED Strip Light Voltage Explained

What voltage do LED strip lights use?

LED strips run on low-voltage DC (direct current) power, not the 230V AC mains supply. A driver or power supply converts the mains AC to the correct DC voltage for the strip. The most common voltages are:

• 24V DC — the professional standard. Better voltage drop performance, lower current draw, longer maximum run lengths. The entire Lumily LED strip range is 24V.
• 12V DC — common in older product ranges and budget strips. Higher current draw for the same wattage, more susceptible to voltage drop.
• 5V DC — used in some addressable LED strips. Not used in standard architectural installations.

12V versus 24V: what actually changes

The physics comes down to Ohm's Law: Power (W) = Voltage (V) × Current (A). A 10W/m strip at 12V draws 0.83A per metre. The same strip at 24V draws 0.42A. Lower current means less resistance heating and less voltage drop along the run.

• 12V strips: maximum recommended single-feed run 3 to 4 metres before noticeable dimming at the far end.
• 24V strips: maximum recommended single-feed run 5 metres from a single feed point.

For runs longer than these, feed from both ends, add a mid-feed point, or use a second driver.

What is LED forward voltage?

Forward voltage is the minimum voltage required for current to flow through an LED and produce light. For a single white LED chip, forward voltage is typically 2.8V to 3.4V. In an LED strip, multiple chips are connected in series within each cut section. The strip is engineered so that the total forward voltage across each section matches the rated supply voltage.

What this means in practice: if you run a 24V strip from a 12V driver, the LEDs simply will not turn on at all — there is not enough voltage to overcome the forward voltage threshold of the series chain.

Do LED lights run off AC or DC?

LED strips run exclusively on DC power. Your mains supply is 230V AC. The driver performs two functions: it steps the voltage down from 230V to 24V or 12V, and it rectifies the alternating current to direct current.

This is why you cannot connect an LED strip directly to the mains — even if you stepped the voltage down with a transformer, the alternating current would cause the LEDs to flicker at 50Hz.

How to calculate the right power supply

Step 1 — find the wattage per metre of your strip (e.g. 14.4W/m).

Step 2 — multiply by total run length. 6 metres × 14.4W/m = 86.4W.

Step 3 — add 25% headroom. A driver should run at no more than 80% of its rated capacity. 86.4W × 1.25 = 108W. Round up to the next standard size — in this case a 120W 24V driver.

Step 4 — confirm the driver output voltage matches the strip. For all Lumily LED strips, that is 24V.

What happens if you use the wrong voltage?

• Strip voltage too high (e.g. 12V strip on a 24V driver) — the LEDs burn out permanently within seconds.
• Strip voltage too low (e.g. 24V strip on a 12V driver) — the strip will not reach full brightness and may not turn on at all.
• Connecting to a battery — a 12V leisure battery will power a 12V LED strip. 24V strips cannot be connected to a 12V battery.