Abstract: A cabinet for housing modular electrical switchgear is formed essentially by a case on which a cover is tightly fitted, and by a window disposed on the cover to seal an opening arranged on the cover. The window bears on the edge opposite its rotation axis, a lug having a recess receiving a clip-in locking button. The locking button has clip-in fingers which exert a return force on the button in the locked position. The button comprises holes coming in the locked position opposite conjugate holes of the cover for a sealing wire to be fitted. The fixing screws of the cover to the case have holes for the passage of a sealing wire which emerges in an outwardly curved passage, for ease of insertion of the sealing wire.