Disclosed is a monitoring system (2) for cable, pipe or wire transits (1; 1a . . . 1n) of a type which has a plurality of transit elements (10, 20, 30, 40; 42; 400) to be assembled into a sealed installation of one or more cables (2), pipes or wires at a site (5). Each transit (1; 1a . . . 1n) has a transit guard unit (50; 50a-50n; 150; 250; 350; 450) configured to detect a condition indicative of whether the installation of the cables, pipes or wires in the transit is sealed or at least potentially not sealed. A central monitoring unit (70) is configured to receive, over a communication network (60; 60b), first information (110, 112) about the condition detected by the transit guard unit (50) of any of the transits (1a . . . 1n). The central monitoring unit (70) registers the particular transit (1a) as being in a first state (GREEN) when the received first information (110) indicates that the installation of the cables, pipes or wires in the transit is sealed, or as being in a second state (RED) when the received first information (112) indicates that the installation is at least potentially not sealed. While the particular transit (1a) is in the second state (RED), the central monitoring unit (70) receives second information (114) about the condition detected by the transit guard unit (50a) of the particular transit (1a). If the received second information indicates that the installation of the cables, pipes or wires in the transit is sealed, then the registered state of the particular transit (1a) is changed to a third state (YELLOW). The central monitoring unit (70) makes the registered states (GREEN, RED, YELLOW) of the respective transits (1a-1n) available to a user (3, 4) of the monitoring system (2).