Many Amel boats have been modified (ours included) and perhaps this binding wire was for a piece of equipment that had a metallic connection to saltwater, but that piece of equipment is no longer there.
For example we replaced the Calpeda Air con pump with a March pump. The Calpeda pump is all metal and has a bonding wire connected usually to the metal one way valve on the outlet. The March pump has no metal parts in contact with salt water hence no need for a bonding wire...so it is no longer connected.
Rather than a list of components, as I said many Amels have been modified, you should check and be sure that EVERY metallic part that is in contact with sea water has a bonding wire attached to it...and that bonding wire is connected to the rudder zincs.