Lighting system comprising: - an electrified track comprising a bar with U-profile defining a cavity within which a plurality of electrical conductors are housed, connectable to a power supply network for receiving an alternating current; - a power supply comprising: - first electrical input terminals connectable to said electrical conductors for receiving said input alternating current and first electrical output terminals for supplying a constant output supply voltage, - first constraining means configured for mechanically constraining said power supply to said electrified track; - at least one optical device provided with at least one light source and at least partially housed within said cavity, said optical device comprising second constraining means configured for mechanically constraining said optical device to said electrified track and second electrical input terminals electrically and mechanically connected to said first electrical output terminals for receiving said constant input supply voltage for electrically supplying said at least one light source; wherein - said at least one optical device comprising second output electrical terminals electrically and mechanically connectable to said second electrical input terminals of a further and separate optical device for transmitting said constant supply voltage to said separate optical device; - said power supply is housed hidden inside said cavity of said electrified track, characterized in that said at least one optical device is an optical device module. - an electrified track comprising a bar with U-profile defining a cavity within which a plurality of electrical conductors are housed, connectable to a power supply network for receiving an alternating current; - a power supply comprising: - first electrical input terminals connectable to said electrical conductors for receiving said input alternating current and first electrical output terminals for supplying a constant output supply voltage, - first constraining means configured for mechanically constraining said power supply to said electrified track; - first electrical input terminals connectable to said electrical conductors for receiving said input alternating current and first electrical output terminals for supplying a constant output supply voltage, - first constraining means configured for mechanically constraining said power supply to said electrified track; - at least one optical device provided with at least one light source and at least partially housed within said cavity, said optical device comprising second constraining means configured for mechanically constraining said optical device to said electrified track and second electrical input terminals electrically and mechanically connected to said first electrical output terminals for receiving said constant input supply voltage for electrically supplying said at least one light source; wherein - said at least one optical device comprising second output electrical terminals electrically and mechanically connectable to said second electrical input terminals of a further and separate optical device for transmitting said constant supply voltage to said separate optical device; - said power supply is housed hidden inside said cavity of said electrified track, characterized in that said at least one optical device is an optical device module.