Electrical advice

[pappas]

Got a quick question about an air con that I'm about to install. It's a 3 phase unit that draws 18.5amps per phase. Can anyone tell me what size cable I should run to it?

[xa-mont]

http://www.csgnetwork.com/wiresizecalc.html

suggests about 14Ga unless you are going over like 200 feet.

[uncle pervy]

and what bike did you say your putting this on?? and could you post pics. i would be interested in that
=]

[pappas]

Thanks XA. I think I might have to run a 25amp fuse so minimum 4mm2.

Not on a bike Pervy. The air con weighs more than a goldwing!

That's an American website.

AS/NZS3008 'Electrical Installations -- Selection of cables' is the Aussie standard you need to work to for this.

Simply saying '4mm2' may not be the best answer.

What type of cable are you running?

How will it be mounted?

4mm2 four core Thermoplastic cable mounted on a wall with clips is rated at 29 amps. Run the same cable exposed to sunlight and it's de-rated to 23 amps.

Not trying to be a smartarse but if shit happens, insurance companies are always looking for a way out of paying on a claim.

I'm an apprentice electrician but I know there's a tradie or two round here who should be able to confirm.

[Shadowzone]

The reason it is derated is because of the increased heat generated by the sunlight which risks the heat damaging the external insulation.

It is all "fit for purpose" installations, and 4mm "should" be able to handle the current, but 6mm will do it so much better. Some of the things you need to look at are where the cabling will be running meaning through a conduit pipe or through a ceiling cavity, how much heat will it be exposed to, is there any chance it will be under or through insulation which will hold the heat generated by the current flow around the cable?

I would be spending the extra money on the heavier cable and using that. But I always like a large margin for error especially when it comes to electrical wiring.

[Redmohawk]

bigger the cable lower the resistance lower the resistance lower the heat and loss , more power at the air con for the same money! Running costs will be lower for the same temp accived "if" the aircon very switches down to curculation only. Over a few years the extra expence of heaveyer cables will be absorbed by the reduced running costs (also amplified savings if the price of your electricity goes up)

[pappas]

Thanks for the advice. I'm going with the 6mm to the aircon.