There are four main types of threads bulbs for home / office. These are the E14 and E27, which are symbols of threads Edison, working on AC voltage of 230V, MR16 and GU10 and symbols that are primarily for mounting bayonet halogen bulbs (now also perfectly suited for LED light bulbs), working in voltage AC 230V or AC / DC 12V. When purchasing and fitting bulbs should be carefully checked the markings on the package, and make sure what type of installation you want to connect the light bulb.
Be especially careful when choosing light bulbs with MR16 thread, because there are 230V and 12V models. In the case of 12V MR16 bulb is necessary to use a transformer reducing the voltage from 230V to 12V, but is recommended to use magnetic transformers (toroidal), which in contrast to an electronic transformer, do not require a certain minimum load on the secondary side, and ideally work with LED bulbs. MR16 LED bulbs are perfect for installation of 12V power such as solar panels or from the emergency power supply.