Why does a house only need 10A power but a van need 15A?

Its more for the Aircon than any thing else. If you look at home your Aicon will be on a 15amp Breaker or even a 3phase circuit.

A normal house has multiple 15A circuits that are fitted with 10A outlets. The theory behind this is that you are extremely unlikely to be using sufficient high powered devices at the same time to cause an issue.

in addition they normally have more than 1 light circuit AND THEN separate circuits for the water heater, stove and built in air conditioner.

With your caravan it is quite reasonable to expect that you will be using the air conditioner and the water heater at the same time,.

It is also quite possible that you will park in a CV park and immediately on connecting the 240v power lead and on opening the van switch the air conditioner on (as the van is hot inside) and also boil the electric jug for that essential cup of tea or coffee, and at the same time the water in the heater is cool so the heater starts to heat that water. With just those 3 units operating you may have already exceeded the 15A maximum power draw that is the rated capacity of the electrical connection.

Hope this answers your question.
Athol

A household's wiring is divided into several circuits.
Heavy current items such as airconditioners, stoves & ovens run off dedicated 15A or 20A circuits. 10A power circuits are usually divided into two separate runs to different parts of the house and the 8A lighting circuit separate again.
The feed into the House can be rated at 50A or more, so it is able to carry the heavier load a household may require.
A caravan has only the one flexible lead to supply the entire load requirements and 15A is the minimum adopted. Many caravans have heavy load items such as airconditioners and a 15A circuit is required to support them.
Apart from the standard 10A power outlets to run toasters, etc., all other appliances such as ovens and fridges are either run on LPG, or limited to a 10A maximum load.

My old van is a popup Sunwagon, no air con, no heated water, kettle is on the stove as is toaster. No heater either. the most things on at the same time would be the fridge , lights and a phone charger, maybe, my phone will last almost a week.

Sandman, that 50A coming in, that alone explains why and answers my question perfectly, thank you.

Electric kettles usually draw 1800 to 2400 watts. That's 7.5 to 10 amps straight up.
You may be using a gas stove to heat water, a lot of caravanners use an electric kettle.
An electric toaster can draw 800 to 1500 watts. The average is 1200W. That's 5 amps.

A microwave is only around 50% efficient. The "power rating" of the microwave is only the power put out by the Magnetron, not the power draw from the plug.
So, if your microwave power setting is 1200W, it will be drawing around 2400W (10A) from the plug.

Add to the draw, 2 or 3 lights, a charger, and the microwave on standby, an electric clock - and before long, the total draw on the caravan power point in the park is over 10 amps.

More than 2 people in a 'van, the more likely the chances of multiple electrical devices being used at once.

Finally - the lead-in cord to a 'van is usually 10M minimum, some caravan cords are 15M, to allow for plugs on the opposite side of the 'van, or an inability to get close to the power point due to obstructions.
Some caravanners have been known to connect 2 or 3 extension leads to get power to their 'van.

Long extension leads lose current transfer ability due to wire resistance. A 15M, 15A extension lead is a basic requirement, to reduce voltage drop, which can damage sensitive electrical items.

A power supply to a house has a short lead-in to the meter box - from which, the 10A wiring is distributed from room to room, via wiring that is designed to be heavy enough to cope with the total draw (number of plugs) in that room.

Cheers, Ron.

Until recently it was legal to have a 10A inlet to a caravan. That made a lot of sense for those without high current draw devises on board and meant it could be easily connected to any 10A supply.

That was changed relatively recently and now means you MUST plug into a 15A outlet, or also use an approved converter at great expense.
I don't know why the change was made.
Cheers,
Peter
OKA196 motorhome

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There are some very comprehensive responses above that do not simply address the OP's question.

Firstly ILovecamping, houses do not "require a mere 10 amp wiring system". The house system is more complex than that but you are possibly confused by the "10A" rating of each power outlet.

Now, to the actual reason for 15 Amp supply in caravan parks:
Modern vans often require more than 10A for their appliances and outlets so the Australian Standard (AS/NZS 3001, 2008) was issued requiring a 15A rated pillar outlet for each van in parks and van wiring was also required to be 15A rated.
Older caravans were manufactured with wiring, inlet sockets and extension cords that were only rated to 10 Amps. However it was possible to connect multiple appliances within these vans which would attempt to draw in excess of 10 Amps and this would overload the 10A input socket / flexible cable and the 15 Amp circuit breaker in the park pillar may not interrupt the current. Accordingly it is not permissible to connect a 10A rated van to a 15A rated supply source unless special arrangements are made.

These 'special arrangements' are essentially the provision of fitting the van with a circuit breaker which will limit the current to no more than 10A AND having the flexible cable supplying the van terminated with a fixed connection at the van, that is without a plug-in input socket.
OR supplying the 10A rated van with its 10A rated input extension cable via a device (such as the Ampfibian) which limits the supply to the extension cable to 10A. There are constraints applicable there too and some van park operators do not understand either of the options above and so will require that only 15A wired vans be connected to their pillars.