depends on cable type if armoured 4 core using the armour as the earthIf you need a neutral then 5 core wire, 3 phases, neutral, earth.
When the cable gets to to the workshop I will be taking a 240v supply off one phase.
In a home workshop environment it's gonna make zero difference.Maybe the professionals would comment here, but I have always understood it to be a good idea to try to balance the single phase demand between all three phases rather than draw it all off one of the phases.
@brightspark its a new install and I am open to 4 or 5
When the cable get to to the workshop I will be taking a 240v supply off one Phase.
I am attempting to future proof myself as my current 3 Phase from another location ..may be too much hassle in the future.
I have the oppertunity to get it in whilst laying ducting for everything else (data, water, ASHP..etc)
I am going to go with 5 core 16mm as this would cover 100a if we go down that route, new connection there shouldn't be an issue with earth.
I always use 5 core, seams daft not to, much nicer to work with, plus it keeps everyone happy, only need one awkward inspector kicking up a fuss - I've no idea how this works 'by the rules' just my real life experience, and I'm not an electrition
25m long, 63amps, 10mm gives 0.6v drop, 16mm gives 0.23v drop
It all depends what size you are working with, as size increases there can be a significant cost saving using 4 core as opposed to 5 core.
16mm will not be suitable for 100a TPN, it will probably only just be suitable for 63A TPN if you do the calculations.