Good practise is that wires attached to moving parts should be mechanically supported. So all the wires to the bed should be attached to the bed or carriage. Pclips or tyraps can be used. Often the suppliers don't provide a fixing point (hole) so you have to use your initiative. You also have to remember the hot bed can melt some plastics hence I mention attaching to the carriage.
You should do the same for the X carriage.