Theoretically speaking it is possible. However it depends on application-as current carrying capacity, armouring, earthing, bending radius, reduced smoke and other.
1.8/3.3 see BS 5467 and for 12/20 IEC 60502-2.
@7anoter4, the cable size is the same 3x185mm2, since the market availability (due to minimum length purchased) is only the 12/20kv despite of requirement 3.6/6kv. Thank for the feedback.
