Identify the installed driver and distinguish supply, dimming, load and driver faults.
Start by checking the mirror’s normal wall switch and any supported lighting control. If it remains dark, have a qualified electrician identify the mirror and read the complete driver model before taking measurements. Turn off the circuit before opening the mirror or handling connectors.
The attached Mean Well LPF-60D sheet covers several output voltages. Only the LPF-60D-24 column specifies nominal 24 V DC and 2.5 A; other suffixes have different ratings. Do not apply a universal 24 V test to every mirror.
The electrician should verify the specified incoming supply, secure connections, the installed dimming/control arrangement, and the LED load before condemning the driver. This driver family has current limiting and short-circuit protection that can reduce or cycle its output; a low or intermittent reading does not by itself prove that the driver is defective. In constant-current operation, output voltage also depends on the LED load.
The LPF-60D’s documented dimming methods use its separate control leads with a compatible low-voltage, PWM or resistance signal. That is not approval to install an ordinary line-voltage wall dimmer. Use the mirror manufacturer’s specified control and replacement parts.
Source: attached Mean Well LPF-60D series data sheet, Specifications, Dimming Operation and Driving Methods of LED Module.
