The Medway Handyman wrote:

I was just after a quick rule of thumb guide so I could measure to outside
of the insulation & tell if it was 4mm or 6mm without having to disconnect
things & get a vernier out. 2.5mm was just used as an example.

I've posted this befo

CSA (CPC) Strands Overall
mm^2 No./dia. mm approx.
--------- ------- ----------
1.0 (1.0) 1/1.13 4.5 x 8.2
1.5 (1.0) 1/1.38 4.7 x 8.2
2.5 (1.5) 1/1.78* 5.3 x 9.9
4.0 (1.5) 7/0.85 6.1 x 11.4
6.0 (2.5) 7/1.04 6.8 x 13.1
10 (4.0) 7/1.35 8.4 x 16.8
16 (6.0) 7/1.71 9.6 x 19.5

* or 7/0.67

--
Andy