Thanks for all the help (and chicken puns).
In answer,
1) I have no idea how the wiring is done inside, but there is a single weatherproof socket on an outside wall. I am just plugging a standard plug into it.
2) The area is large - we have 50-60 chickens and it needs to seem like...
We have free-range hens that need floodlighting to lay year round. I have attached a security floodlight to arctic cable which is plugged into an outside plug (weatherproof).
Sadly this light is insufficient. How do I attach more lights to the circuit? And what is the maximum total...