How can I illuminate inverters, switches and buttons of the Plana series so that they are lit and visible in the dark, and not illuminated in the presence of ambient light?

With a 00931 pre-wired signalling unit which illuminates devices in the dark without the need for any extra connections. Illumination units provided with cables (e.g., 10493) illuminate devices which can accommodate them or signal the operating status of the associated loads.