My own Western knowledge told me the power cable from the consumer unit goes to the outside condensor unit first; THEN a 4 core including the programming goes to the internal white box.

So of course you ask......

 

1. a Thai electrician (a proper one) tells me the power goes to the internal unit first

2. a (seemingly)knowledgeable chappie at Siam tv tells me it also goes to internal unit first

3. a technical specialist at Daikin service centre tells me it goes to the outside box first

 

so I have 2 votes for each??

 

I am installing aircon but i want to set up all the flexi conduits and cables as a first fix before I close up the walls with plasterboard and teak.

 

As far asI can  see I possibly doesnt matter as there is an electrical connection block in each unit and they are both connected anyway, but it may also be dependant on the manufacturer/size of the unit

 

If you do know, which of your boxes was the main power taken to initially?

First thing you need to understand is that Thai electricity is different to farang electricity, sort that out and all will become clear. 

Actually, it doesn't matter, >90% of split-unit air can handle either way round.

 

Ours are all wired with power to the indoor units, coz that's what our sparks said.

Yah.  I had this debate when first installed the AC as I had power to both in and out ('cause I thought that's what's needed).  The AC guy said it didn't matter so I went with outside as that is the one I had on separate circuit.  The point is:  IT DOESN'T MATTER.  So, if somebody is saying it does, you may suspect as not knowing the job.

Not knowing the job, now that would be unusual, wouldn't it? 

My experience is the same as above. I once routed to the outside unit point which one spark didn't like so now I always route the cabling from CU to the indoor aircon point and had no frowns from whoever comes to fit the unit.

The only notation in the installation manual for our Mitsubishi unit is as under

I have 7 split A/Cs in my house....the power cable outlets for my A/Cs are on the inside where the inside unit is mounted on the wall.  My house was built with electrical wiring outlets right at the points an A/C would be mounted. Then power/control wiring runs from the inside unit to the outside unit....that electrical cabling is contained within the plastic conduit on the outside wall that also contains the two refrigerant pipes connecting the inside and outside unit together.  

 

 

 

 

 

For easy installation, supply would go to the indoor unit on single phase systems where the indoor unit switches the compressor load.

 

Where compressor load is handled at the outdoor unit (higher capacity and split systems) the supply should go to the outdoor unit.

 

The Thais will often make a mess of a high capacity installation by splitting the supply in a ceiling and not at the outdoor unit.

believe I would follow the OEM installation instructions with regard to the power connection...if ye don't ye risk a warranty issue if there's an electrical problem arising in this regard...