Quote Originally Posted by baldrick View Post

1.5 mm2
2.5 mm2
4 mm 2 - though this is debatable depending on the actual current draw of the aircond and the heater

just make sure he runs separate circuits for the power and the lighting - you should also maybe have 2 or 3 power outlet circuits with an equal number of outlets on each
Water heater is 6000W

Air con I do not know.... But, Bedroom one is 12 sqm floor area with an 2.5 metre ceiling. I was going to buy 9000 BTU... Saw a 7000BTU (Samsung) on special in "Global House, Lamphun" if that would suit a 12sqm floor area (About 30 cubic metres)... I would save money. It is priced at 8990 Baht.

May suit 2nd bedroom as there is a lower ceiling. Same floor area 12sqm but, only 24 cubic metres.

Lounge/passage is 38 sqm facing west (afternoon sun) about 90 cubic metres. Not sure of "optimal" BTU required here? Will research.

Unless there is a "guru" on here who can genuinely advise, both efficiency and running cost.

Ennis