24V DC or 230V AC? Choosing the supply for hotel furniture lighting

Both voltages work. The question is where the driver lives, who is allowed to touch the wiring, and how much voltage drop you can afford over the length of a wardrobe. This guide is written for furniture factories and project specifiers who have to commit before the first sample is routed.

What the two options actually are

A 230V AC fitting contains its driver and connects directly to the mains. It is Class I (earthed) or Class II (double-insulated) under IEC 60598. A 24V DC system puts the driver elsewhere and runs extra-low voltage to the fitting; the fitting itself is Class III (SELV), which is why it needs no earth and no insulation test on site.

In a hotel guest room the practical difference is who terminates the wiring. A 24V fitting can be connected by the furniture assembler with a pluggable connector. A 230V fitting needs a qualified electrician at the furniture plant or on site — and in most projects it changes who carries the liability for the last metre.

Voltage drop is the real constraint on 24V

A 24V run is short. Doubling the current for the same wattage means four times the loss for the same cable, so the length limit arrives quickly. Use the loop resistance, not the one-way resistance:

V_drop = 2 × I × R × L   ·   I = W ÷ 24

With 0.5 mm² copper (≈ 34.8 Ω/km at 20 °C) and a 10 W/m linear light over 10 m, the current is 4.2 A and the drop is about 2.9 V — 12% of 24V. That is already past the point where a 24W driver compensates: you lose light output and the far end goes visibly dimmer.

Maximum run length, in practice

Keep total drop under 5% (1.2V on a 24V system). Indicative maximum run for a single feed, 24V DC:

Calculated at 5% drop, 20 °C copper, single feed at one end. Feed from both ends to double these figures.

Two habits solve most problems without thicker cable: feed from the middle of a long run (halves the effective length), or use one driver per cabinet section instead of one driver for the whole wall of wardrobes.

Where the driver goes

This is the part that fails on site. A driver needs air and access; a wardrobe back panel gives neither. The three workable positions, in order of preference:

1. Remote, in the plinth or a service void — 18–20 mm slim drivers fit behind a 100 mm plinth and stay serviceable without dismantling the carcass.
2. In the top box above the wardrobe — good access, but check the temperature: an enclosed top box with no ventilation will derate the driver and halve its life.
3. Inside the carcass behind a removable back panel — only if the panel is genuinely removable after installation, not screwed and veneered over.

Dimming and control compatibility

For 230V fittings the dimming method has to be decided before the room's wiring is installed: trailing-edge mains dimming, 0–10V, DALI, or a proprietary RF module inside the fitting. For 24V systems the driver decides — PWM drivers dim smoothly to 1%, while cheap constant-voltage supplies buzz and drop out below 10%.

Ask for the dimming curve, not just the protocol name.

A short decision rule

Use 24V DC when the light is inside furniture, is small, is repeated many times per room, or must be assembled at the furniture plant. Use 230V AC when the fitting is exposed, needs to be replaced without touching furniture, or the project standardises on mains-voltage drivers for maintainability.

In practice most hotel casegoods end up hybrid: 24V inside wardrobes and headboards, 230V for the mirror light and any downlight in the ceiling. That is fine — as long as the drawings show which is which and the driver locations are serviceable.

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