In article ,
"Christian McArdle" writes:
I have recently finished a complete rewire where the parts cost was
about £400 - three rings, two radials, two lights, cooker, shower,
immersion, data, all new parts. They had a £60 CU, swapping that
for a £250 one would have increased the parts cost by some 50%

As RCBOs cost around 40 quid [...]

Not from an electrical wholesaler...

--
Andrew Gabriel