On Wed, 13 Feb 2019 23:42:42 +0000
(Roger Hayter) wrote:

Does anyone know of a readily available connector to directly connect
some 10mm T&E to 2.5mm T&E, that will go in a reasonably small box? I
suppose I could use just some of the strands, but that would be rather
poor practice. The best I have thought of (and have) is a surplus DIN
main switch, left on of course. Any superior ideas?

60A chocblock might do it - strip both cables the full width of the
block, back the screws right off and stick the 2.5mm through and out
the other side. Take a bradawl or similar and make a hole in the end
of the 10mm so you can push the 2.5mm into it, then squeeze it back
carefully with pliers so the 10mm will fit into the block.