An enclosure for electrical installations, comprising a rectangular bottom part and a hinged door to be fastened at a door opening of the bottom part, which bottom part comprises a bottom and sidewalls (3 - 6) extending upward from the bottom, the door being turnable from a closed position in which it covers the door opening to an open position in which it leaves the door opening open, the door being fastened to the bottom part by means of a door frame detachable from the bottom part, and the enclosure comprising a cover which covers the door frame and the door, which cover is fastened to the bottom part, characterised in that - the door frame comprises at least two quick-release means (20, 21) to fasten it detachably to at least two detents (23, 24) in the bottom part so that the door frame is locked at the detents (23, 24) and the bottom part when the quick-release means (20, 21) are in the locked position, and the door frame may be released from the bottom part when the quick-release means (20,21) have been opened and released from the detents (23, 24), - two opposite edges (17 and 19) of the door frame comprise said quick-release means (20, 21), whereby the inner surfaces of two opposite sidewalls (4 and 6) of the bottom part, facing the interior of the enclosure, comprise said detents (23, 24), - the quick-release means (20, 21) comprise a locking tongue (20a, 21a), devised as flexible, and in that the detent (23, 24) is on the inner surface of the bottom part interior, on the inner surface of the sidewall (4, 6) of the bottom part, - the locking tongue (20a, 21a) is arranged to receive a first force and to strain and flex when the door frame is being installed to the bottom part by moving it towards the bottom of the bottom part, and in that once the door frame is installed on the bottom part, the locking tongue (20a, 21a) is at the detent (23, 24) and unstrained or a second force is directed on the locking tongue (20a, 21a), which is smaller than the first force, and, correspondingly, the straining and flexing of the locking tongue is smaller than the flexing and straining thereof when the door frame is being moved towards the bottom of the bottom part, and - the door frame covers the door opening so that access to the locking tongue (20a, 21a), in order to open the locking position of the locking tongue, requires the door to be opened, whereby as the door is open, a first surface of the locking tongue may be accessed in order to apply external force on its first surface so that the locking tongue flexes and the locking tongue is released from the detent (23, 24) in the bottom part, whereby the door frame may be lifted off the bottom part. - the door frame comprises at least two quick-release means (20, 21) to fasten it detachably to at least two detents (23, 24) in the bottom part so that the door frame is locked at the detents (23, 24) and the bottom part when the quick-release means (20, 21) are in the locked position, and the door frame may be released from the bottom part when the quick-release means (20,21) have been opened and released from the detents (23, 24), - two opposite edges (17 and 19) of the door frame comprise said quick-release means (20, 21), whereby the inner surfaces of two opposite sidewalls (4 and 6) of the bottom part, facing the interior of the enclosure, comprise said detents (23, 24), - the quick-release means (20, 21) comprise a locking tongue (20a, 21a), devised as flexible, and in that the detent (23, 24) is on the inner surface of the bottom part interior, on the inner surface of the sidewall (4, 6) of the bottom part, - the locking tongue (20a, 21a) is arranged to receive a first force and to strain and flex when the door frame is being installed to the bottom part by moving it towards the bottom of the bottom part, and in that once the door frame is installed on the bottom part, the locking tongue (20a, 21a) is at the detent (23, 24) and unstrained or a second force is directed on the locking tongue (20a, 21a), which is smaller than the first force, and, correspondingly, the straining and flexing of the locking tongue is smaller than the flexing and straining thereof when the door frame is being moved towards the bottom of the bottom part, and - the door frame covers the door opening so that access to the locking tongue (20a, 21a), in order to open the locking position of the locking tongue, requires the door to be opened, whereby as the door is open, a first surface of the locking tongue may be accessed in order to apply external force on its first surface so that the locking tongue flexes and the locking tongue is released from the detent (23, 24) in the bottom part, whereby the door frame may be lifted off the bottom part.