Hi All,
According to samFIRT and his infomation on 'empirical' evidence it would seem that if at any point during a fire, if the warning system should fail, it would only take one person to return to their desk and everyone else would follow. Therefore this situation appears to be even more urgent than I thought!
OK for anybody who does have a blind-spot for drawings then I will do my best to explain those that I have sent to Kurnal:
The first two represent a 'radial system' as they are defined within British and International electrical engineering dictionaries, the top drawing simply represents eight sounders that have been individually supplied as 'spurs' from the CIE and they are represented around the circumference of an imaginary (somewhat squashed) circle. The bottom drawing is in the 'schematic' form and shows the CIE enclosing eight fuses each one of which protects a single sounder, the sounder to the far right is shown as being on fire and its' supply cables are shown as 'dotted lines' in order to highlight the fact that the fuse has ruptured due to short-circuit in the cable and this this sounder has ceased to operate, whilst the other seven sounders are continueing to operate during the fire.