"Colin" wrote
| 15 lights
| 50W per light

That'll be 2 new lighting circuits then, as each point must be rated at 100W
..

| I assume that low voltage downlighters cost the same to run
| as mains voltage(?)

LV cost a lot less to run in bulb replacement costs, apparrently.

And you'll only require 1 new lighting circuit as you can run 5 transformers
at 150W each.

Owain