A luminaire or electrical unit for connection to a support rail, which has a support rail profile with two side walls and at least one busbar, which is arranged on one of the two inner sides of the side walls of the support rail profile and has electrically contactable lines, the luminaire or the electrical unit having a contacting element for electrical and, where applicable, mechanical connection to the support rail, and the contacting element being insertable into the support rail profile and having connection contacts, which are adjustably mounted so as to bear against lines of the busbar in a state in which the contacting element is inserted into the support rail profile, the contacting element having at least one linearly laterally adjustable contact block (61, 62) which has connection contacts and is adjustable between an open position, in which insertion and removal of the contacting element from the support rail profile is made possible, and a contacting position, in which the contact block (61, 62) with the connection contacts is extended laterally for contacting the lines, the contacting element having two contact blocks (61, 62) comprising connection contacts pointing in opposite directions, both contact blocks (61, 62) being coupled in such a way that by moving them apart, starting from the open position, they can be transferred into the contacting position, characterized in that the two contact blocks (61, 62) are pre-tensionally mounted in the contacting position, pressing or actuating elements (71, 72) being arranged on the contacting element or on a carrier element of the luminaire or the electrical unit, which pressing or actuating elements enable the contact blocks (61, 62) to be manually pressed together into the open position. the luminaire or the electrical unit having a contacting element for electrical and, where applicable, mechanical connection to the support rail, and the contacting element being insertable into the support rail profile and having connection contacts, which are adjustably mounted so as to bear against lines of the busbar in a state in which the contacting element is inserted into the support rail profile, the contacting element having at least one linearly laterally adjustable contact block (61, 62) which has connection contacts and is adjustable between an open position, in which insertion and removal of the contacting element from the support rail profile is made possible, and a contacting position, in which the contact block (61, 62) with the connection contacts is extended laterally for contacting the lines, the contacting element having two contact blocks (61, 62) comprising connection contacts pointing in opposite directions, both contact blocks (61, 62) being coupled in such a way that by moving them apart, starting from the open position, they can be transferred into the contacting position, characterized in that the two contact blocks (61, 62) are pre-tensionally mounted in the contacting position, pressing or actuating elements (71, 72) being arranged on the contacting element or on a carrier element of the luminaire or the electrical unit, which pressing or actuating elements enable the contact blocks (61, 62) to be manually pressed together into the open position.