There is no simple answer to this. First of all, you have to consider if you want to illuminate a certain area with a lamp (e.g., 60x60cm with a GCx-4), you have to hang the lamp at least high enough for the light cone to reach the entire area, which in this example would be from a distance of about 15 cm. It is also important to remember that LEDs emit a certain amount of heat. Depending on the ventilation, it may therefore be necessary to maintain a certain minimum distance due to the heat.
