Three phase cable to wire single phase

[ambr111]

Can I use three phase cable to wire single phase

 

[James]

Safely terminate the spare cores
ensure you have marked the cables in use with correct colour sleeves

edit, just been pointed out to me that this is not a U.K. issue.
above is what we would do over here normally.
can’t be certain if it’s suitable advice for down under.

 

[westward10]

This is Australia.

 

[AlfInAussieland]

Can I use three phase cable to wire single phase

James is correct with some caveat.
So the answer is YES...NO
The below examples would be as per AS/NZ3000 regulations:
I have done so where it was used as a submains where you used the 4 wires to double up on Active/Neutral to reduce the Voltage drop. Here a separate remote earth is used..so no problem.
If you would want to use it to increase the current rating...lets say for 15A Outlets on 2.5mm2 cable...then you have to add an additional separate earth wire. Most Electricians would snub their nose on this....but it is certainly within regulations.
So its not a colour code problem as long as they are identified what are actives and what are neutrals as per Jame's reply.