If a voltage other than the mains voltage (220 Volts) is needed to supply electricity to an appliance or building, a transformer is necessary to step this voltage up or down. Low voltage lighting, as its name suggests, needs 12 Volts to operate safely and correctly. A transformer may be used to step the mains down to this level. On the other hand, the industry may need higher voltages than can be supplied by the utility and uses transformers to step up to the required level.
Information supplied by Buildaid Publishing.