Browse Forums Heating, Cooling & Insulation 1 Mar 15, 2009 10:11 am Hi there,
We are currently building (almost at lockup stage) a 230m2 house with a 15kW single phase air conditioner the brivis ice cooler. Our sales consultant told us that we would only need single phase power. I read a post here that says that 80A * 230V = 18,400 W and I have noticed that a lot of houses only have 80A main circuit breakers. So therefore running a 15kW air conditioner system would leave only 3.4kW spare power? I am concerned because I'm not sure if I have enough power to run my house. We have the normal things like plasma TVs, projectors, 3 computers, fridge, washing machine, dryer, microwave, vacuum cleaner. We also have 20 downlights. We are intending on installing a pool later, therefore some kind of pump will be required, I guess this is another 1 kW or so? How is the meter box normally setup, for instance can I add more ampage on the main circuit breaker? Should I get 3 phase power? Is it too late to get 3 phase power if a single phase air conn is installed? Thanks for any advice. Re: Single or 3 Phase Power, Meter Box - some advice please 2Mar 15, 2009 1:17 pm hi there, wel, thats quite a conundrem...
it is possible to change to 3 phase power, BUT it will be tricky. A)you will have to change the mains cable going to your meterbox which will add a cost. B) the builder will need to ask your power supply authority to connect to 3phase and organise to have more power going to your house which may cost more depending on your builder... it doesnt sound like you have too much stuff in your house, the average size house draws somewhere around 63A per phase....also dont forget that you wont have everything running all at once. another option is to just ask the supple authority to draw more power to your meter box and upgrade your main fuse...this is limited tho depending how big your mains cable size is Re: Single or 3 Phase Power, Meter Box - some advice please 3Mar 15, 2009 6:44 pm Air conditioners are confusing when it comes to power. There are two powers to consider:
1) How much electrical power they consume 2) How much heat power they move. Now an air conditioner that uses 1 kW of power can provide 3 kW of cooling. This is one of the rare times that you get an efficiency above 100%. Now, before you think we've invented a perpetual motion machine, keep in mind that an air conditioner is a heat pump and that the energy is coming from the sun. Now, when you ay 15 kW,changes are the air conditioner uses 5 kW. Still that's a whopping 21A!!!! Anyway, you need to look at how much power your air conditioner uses. Demolition August 2009, Construction Started September 2009, Completed December 2010 Re: Single or 3 Phase Power, Meter Box - some advice please 4Mar 15, 2009 8:42 pm Hi all,
Thanks for the helpful replies! Good point casa2 regarding power consumption, I have to admit I didn't realise 15kW was the cooling capacity lol. Thank you so much for informing me of this before I made a fool of myself I spoke to the air conn guy the other day about the unit. I think he said it was the CDU15A-7H or CDU15A-7D. http://www.brivis.com.au/web/BrivisWeb. ... ioning.pdf The air conn only uses 26.1 A so around 6kW of power. I just checked on my electric oven too and that uses about 13-15A (2.8kW with a 15A plug). That leaves me a lot more power/amps than I thought as that's 40A with both the oven and air conn running. We should be ok with 80A. I will make a new topic in another forum regarding my queries over household device power consumption. Two more questions: 1.) The two air conn units listed above differ in that one says Single Phase Hard Start the other Single Phase Soft Start that seems to be the only difference, does anyone know what this means and the implications? 2.) A friend said that the amps used by things in the house won't matter as long as you have a staggered start even if you want to have them all on at the same time (>80A). Is this true? Thanks again!! Re: Single or 3 Phase Power, Meter Box - some advice please 5Mar 15, 2009 8:50 pm aajinoz Hi all, Thanks for the helpful replies! Good point casa2 regarding power consumption, I have to admit I didn't realise 15kW was the cooling capacity lol. Thank you so much for informing me of this before I made a fool of myself I spoke to the air conn guy the other day about the unit. I think he said it was the CDU15A-7H or CDU15A-7D. http://www.brivis.com.au/web/BrivisWeb. ... ioning.pdf The air conn only uses 26.1 A so around 6kW of power. I just checked on my electric oven too and that uses about 13-15A (2.8kW with a 15A plug). That leaves me a lot more power/amps than I thought even in the worst case! (40A) So we should be ok. I will have to think about getting LED downlights and maybe getting a solar powered pump for the pool and i'm still not sure on the power consumption of my fridge (double door) and washing machine (front loader), but that I will leave to another forum/topic. Two more questions: 1.) The two air conn units listed above differ in that one says Single Phase Hard Start the other Single Phase Soft Start that seems to be the only difference, does anyone know what this means and the implications? 2.) A friend said that the amps used by things in the house won't matter as long as you have a staggered start even if you want to have them all on at the same time (>80A). Is this true? Thanks again!! point A) best to get softstart. It starts the motor in stages. Reduces current load. Also hopefully your lights wont flicker. point b) your mate is right. When appliances are rated at certain power that is the maximum rate, which is usually at start up. Just dont start everything at once and you will be right. Re: Single or 3 Phase Power, Meter Box - some advice please 7Mar 17, 2009 3:41 pm I am a Qualified electrican so maybe i Can shine some light on this situation. Firstly 15kw is a large air con I must say. Personally if you had a 15kw air con electric oven and electric hot water and you had plans to put in an pool that wasn't solar heated Id suggest you put in 3 phase or at least 25mm2 single phase cable.
Secondly when you mention your house has an 80A circuit breaker this is most likely incorrect. Houses Mostly have 80A main switches this is for isolation of the house only. The supply side most is where you house will be limited and this is normally via fuse. The supply authority control this fuse it is normally about 40 or 50 amps in old houses and 80 - 100 in most new houses more common to find 100A thou. I think you are justified worring about this. Simply adding up the total amount of amps isn't the best method for working out the current your house will draw and wether you need to upgrade your mains or not. What you need done is a Maxiumum demand caluation done on the property and If your serious about getting a pool get them to facttor it in. 1 62023 Thank you so much for the effort. We will use it to talk with builder. We also had idea of building duplex instead and seeking suggest ions. viewtopic.php?f=31&t=106744 11 13833 |