In article , John J
wrote:
On Saturday, 6 February 2021 at 23:15:02 UTC, Theo wrote:
While I was on the TLC website I was doing a thought experiment.

Twin and earth cable comes in a variety of sizes: 1, 1.5, 2.5, 4, 6,
10, 16 mm2.

But what if you want to wire three phase? TLC only have 1 and 1.5mm2
three core and earth. Doncaster Cables also have 2.5mm2 but not
larger. CEF likewise. There's some three core in SWA but I assume
that's primarily for external use?

I understand that using three phase you can get 3x the power compared
to single phase - so a 32A radial would get you 7.3kW single phase or
22kW three phase.

But how should you wire that? For a 32A single phase radial the TLC
calculator indicates it needs 6mm2. What cable do you use for three
phase?

I suppose you could run a pair of 4/6/10mm2 T&E but that would seem
'surprising' - one of those pairs carries two phases instead of live
and neutral, and anyone who mixes up a phase for neutral may be in for
a shock. Plus the colour scheme is confusing (two brown and two blue,
which phase is which again? You can sleeve, but what if you mix up the
cables?)

You could use SWA, but that's fairly unwieldy and pricey for an
internal installation.

So what's the 'proper' way to do it?

Thanks Theo

You could go to a "proper" supplier but are you really planning to
install a three phase circuit in a domestic property or just shooting the
breeze?

does the premises have 3 phases incoming? If not, it might be quite pricey
to have your supply upgraded.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle