DALI bus power supplies are typically available at 100, 120, 150 or 250 mA depending on the vendor (ABB BCO/S, Tridonic DALI-PS, Lunatone PS5), and should be sized for the cumulative current of control gear plus input devices, with a 30 percent margin.

Standard DALI PSU ratings give roughly the following gear budgets: 100 mA for about 15 gear, 150 mA for about 25 gear, and 250 mA for about 40 gear plus input devices. A 30 percent margin is recommended for inrush peaks and future extension. The PSU is often integrated into the KNX/DALI gateway itself to save components. Always verify the exact draw of every gear (some still draw 10 mA).

If the gateway has an integrated PSU, do not parallel a second external PSU — DALI does not isolate PSUs and two sources will fight, eventually frying the bus drivers.