Triple pole triple throw relay
It sounds like your objective is to allow one of several wires to be powered at a time, while ensuring that there will never be more than one powered.

A simple way to achieve this is to feed power into the common contact of an SPDT switch or relay.  The normally-closed contact will power one output.  The normally-open output will feed the common contact of the next switch (relay).  The normally-open contact of the second switch will power a second output, while the normally-closed contact will feed power to a third switch.  This pattern may be cascaded as deeply as desired.

Using this approach, activating the first switch will power the first output and prevent any others from being powered.  Activating the second switch when the first is not activated will power the second.  Activating the third switch when the first two are not activated will power the third, etc.

If one is using relays, it would be possible to use other approaches to ensure that while e.g. relay 2 is activated, any attempt to activate relay 1 would be ignored (rather than having relay 1 "take over"), but such approaches would add complexity.  The approach described should be simple to implement and very robust.