I use the bulb in a boat shed without electricity on a 12-volt battery. The light intensity equivalent to a 40W lamp as indicated. Unfortunately missing in the description of the evidence that you have to pay attention to the exact polarity. If one exchanges plus and minus, then the lamp is broken. Minus is the thread, Plus is the pin. On E27Sockel is thus Plus where normally phase is connected - usually scharzes cable. Because of this "vital" information is missing, a deduction of points. Otherwise, top, you can work with standard installation material and quickly and easily install a battery-powered lighting.