IBM F50 RS/6000 7025 - Manual (Page 244)

5. Connect all cables to the back of the system, then plug all power cords into
properly grounded electrical outlets.
Note: If you are in the United Kingdom and have a modem or fax machine
attached to your system, reconnect the telephone line after you plug in
the power cords.
5-100 IBM RS/6000 7025 F50 Series User's Guide