As an occasional Design Authority for projects that more often than not involve wires ...
The answer will depend on the type of cable, and if there is a possible requirement to re-energise it in the future.
Obviously it needs to be kept out of the way of the working bits of the design, so cutting it off and leaving it dangling is not an option. (And the 1988 Clapham junction crash should be held up as an example of what can happen to anyone who thinks cut and drop is OK.) So take it right out of the box, or make sure it is tied back or put under a spare terminal.
If the cable may be re-used it should not be cut so short it cannot be spliced, and once tied back it should be sealed against moisture ingress. Maybe adhesive lined heatshrink is your friend. Mineral insulated cables need a different approach!
If there is any chance at all of it picking up an unwanted voltage by capacitance to neighbouring conductors, and long runs of multicore mains cable, and the 'mains logic' of some heating systems come into that category, then the unused cores should be connected at least at one end, maybe both, to a know and safe potential, ideally earth.
In some areas (Avionics, telecoms and railways come to mind, there will be others) there will be industry standard methods to be applied. Elsewhere there will probably be house styles.
As an occasional Design Authority for projects that more often than not involve wires ...
The answer will depend on the type of cable, and if there is a possible requirement to re-energise it in the future.
Obviously it needs to be kept out of the way of the working bits of the design, so cutting it off and leaving it dangling is not an option. (And the 1988 Clapham junction crash should be held up as an example of what can happen to anyone who thinks cut and drop is OK.) So take it right out of the box, or make sure it is tied back or put under a spare terminal.
If the cable may be re-used it should not be cut so short it cannot be spliced, and once tied back it should be sealed against moisture ingress. Maybe adhesive lined heatshrink is your friend. Mineral insulated cables need a different approach!
If there is any chance at all of it picking up an unwanted voltage by capacitance to neighbouring conductors, and long runs of multicore mains cable, and the 'mains logic' of some heating systems come into that category, then the unused cores should be connected at least at one end, maybe both, to a know and safe potential, ideally earth.
In some areas (Avionics, telecoms and railways come to mind, there will be others) there will be industry standard methods to be applied. Elsewhere there will probably be house styles.
