"roger" wrote in message
...

The wiring and house are about 25 years old, dry and in vg
condition, standard 7/029 T&E.

"25 years old" and "7/0.029" are not compatible attributes. Metric cable
came into use around 1970, so either the house is older than you think or
you've got stranded 2.5mm^2.

--
Andy