I wouldn't be happy with mains and signal joined with crimps in the same box, especially 1.5mm crimps on a bit of tooth floss size cat 5 big risk of wire pulling out and sticking into a live terminal.
We always insist that signal and mains be terminated in seperate boxes or be contained in seperate compartments in trunking , that is one that I have never had to argue for at site meetings.
Occasionally when Cat5 has to be repaired we use jel crimps http://uk.rs-online.com/web/p/produ...|prd|5104775&gclid=CImBo4ODls8CFWgz0wod3HwIFw
or if there is room, punch down wiring connectors.
The Cat5 would be qualified after the repair at the same time as the electrics were tested, also I would have taken the opertunity to identify as many of the cables as possible, could save a lot of time later.