I need to run a cable from mains supply in house to my cat pens at bottom of garden approx 20 metres. I have three pens and I need to supply low voltage lighting and a small electrical heater and a thermostat to each. Can you please advise on what size armoured cable I need (i.e. 2 or 3 core cable) etc. I think I will need a fuse box in one of the pens. Do I need anything else. Can anyone help me please??