What is a power point's maximum load?

[Else]

How can I work out the maximum load for a power point so I know which appliances can be used at the same time, without problem?

[Else]

Thanks everyone for all the above info. I've learned a lot : ) 

[R4addZ]

Hi @Else 

If it's not connected then it doesn't matter if it is coiled.

One thing that is being overlooked here is that it isn't about the rating of the outlets and that is the issue here in Oz. I'm originally from the UK and things are done differently there. In the UK they install what is known a a ring main. This is where the powerboard links to the first socket, the first to the second the same as here but the difference is that the last socket links back to the power board. This means any load can be shared both ways round the circuit reducing the load placed on any one length of cable. In Oz you have to keep in mind, not the rating of the socket but the rating of the entire spur it is connected to. so if there are 5 sockets on the run , each pulling 8 amps, that is 40 amps being carried by the first length of wire! Not good! You would pop the fuse before getting away with that! I had a house where I had two heaters on the same spur and regularly popped the fuse by plugging in one additional item.

[Else]

Thanks R4addz 😊

So if I've understood... with a ring main, the current flows in a circular fashion/in a complete loop  but in Australia, it flows in a linear fashion... 

Does knowing whether a power point is at the beginning or end of the whole spur help In any way? eg if I'm deciding where best to position an appliance to reduce the chance of blowing a fuse? Or maybe that's another silly question 🤔

I was also wondering:

Are ring mains tricker to install/maintain? Why do we do things differently here? 

I had a builder friend visiting from the UK & he said we position power points differently here too...

[EricL]

Hi @Else 

Let me tag @R4addZ to make them aware of your question. Let me also call on our experienced members @CSParnell and @MikeTNZ for their opinions.

Eric

[Else]

Thanks Eric 

[R4addZ]

Hi @Else 

I'm not sure why we do it differently in OZ (I'm not an electrician) but perhaps cost for the builders is an issue. It won't matter where you plug your device in as the circuit is only rated to suit the maximum load it can take.

[MikeTNZ]

Hi Guys,

The maximum current you can run through any normal socket-outlet, is 10 amps, that is what you can plug into it, it is the same for a double socket-outlet.

Yes you can get larger socket-outlets, say 15 A or 20A, but only an Electrician can install these and check the size of the wiring in behind that socket.

And, 10 amps gives you around about 2400W of power available at that outlet, by rights you shouldn't need any more than that.

Otherwise you are talking about a single dedicated circuit that only an Electrician can install and fit a new circuit-breaker/RCD in your switchboard. 

Should you have any further questions, 

By all means, let me know, I am a qualified electrician. 

[R4addZ]

Hi @MikeTNZ 

Yes the maximum you can plug into any one socket is 10 Amps but the maximum load you can have on any one spur is usually 10 Amps so if you have say 5 outlets on one spur, the total load on that spur is 10 Amps so the rating of the socket is to a certain point irrelevant!  Plug a 2 KW heater into one outlet  (2000W devided by 240V = 8.3 Amps so only about 400 Watts can be plugged in to any or a combination of sockets along that spur!

This isn't so much of an issue these days as LED lamps draw so little power they aren't such an issue but try and plug two heaters in on the same spur and you will trip the power! It would be nice if builders explained these issues to customers so that they can consider whether different rooms should be on seperate spurs but they don't. Maybe this is a niche for a building consultant?

[MikeTNZ]

Hi @R4addZ,

When an electrical installation is designed, the designer usually uses what is known as a maximum demand calculation, this is part of the Wiring Rules.

What this means is that it uses the idea that not all of the socket-outlets on a given radial circuit will all be drawing 100% of their connected capacity at any one time, so there is a certain amount of "diversity" in planning circuits so that a realistically sized cable can be used.

Also, the rating of the given radial circuit is stipulated by the size of the cable used in the circuit and the current rating of the circuit-breaker that protects that circuit, it is also a given that say a 20 Ampere circuit-breaker does not trip at 20A, it is designed to trip at 1.5 times that rating (30A under normal overload conditions).

These days with heat pumps and appliances that are a lot more efficient than they used to be, the actual current draw on an installation is a lot lower than it used to be. 

[R4addZ]

Hi @MikeTNZ 

Thanks for clarifying that but it causes concern for me. A 2.5mm conductor cable is apparently rated to carry up to 20-25 amps and that takes us to a maximum of 6Kw so 3 x 2Kw heaters plugged in on the same spur reaches that limit and you are saying that a 20A fuse shouldn't trip till 30 Amps!!!! That is an accident waiting to happen! The initial length of cable can be taking way more load than it should and considering that a plug in Wok lead gets hot just in normal operation, we are talking about serious danger here. This is why countries such as the UK use a ring main because the load is spread between two feeds, reducing the load on any one cable. Please tell me the regulations don't allow this!