There are 2 electrical systems in caravans 12 volt which runs off a leisure battery, and 240 volt which is like a domestic system.
The 12 volt system always runs the caravan lighting and can be used to power televisions and some other appliances. 12 volt appliances can not be used on 240 volts unless they are duel voltage or a transformer is used. The battery is generally concealed in a cupboard or under seating; a charger will keep the battery topped up when connected to a mains supply, via a zig unit.
240 volt electricity is connected from the site to the caravan with a mains hook up cable, the supply is distributed in the van via a Zig/ consumer unit, the amount of current available is limited, the maximum supply would be 16amps, many sites only provide 10amps and continental sites may only supply 5 amps. Campers must calculate how much current they are using to avoid tripping out the supply. Therefore it is recommended that low wattage appliances are used (they may be slower in use than normal domestic products) otherwise domestic appliances can be used but avoid products which are over 1000W.
Electricity in Tents
Tents must use a mobile mains unit which is protected with its own fuses and RCD; it is protected from rain and condensation with waterproof sockets and connections. It is not safe to use electricity in a tent or outside and campers could cause major problems on a site without this protection. The same rules regarding the amount of current being used applies as with caravans and motorhomes, but having this supply opens up opportunities for more comfortable camping with fridges and lighting even microwaves etc.
Polarity is an issue especially when visiting the continent, as the 2 pin system allows the reversal of live and neutral supply. This could mean that a socket which appears to have been switched off is in-fact still live. It is possible to test using a polarity tester otherwise known as a mains tester it simply plugs into the 240v system and indicates whether the supply is correct. Some campers will have 2 continental adapters wired each way to make a correct connection easily.
How much electricity does an appliance use
To work out how many amps is being used by each appliance you do this sum:
Watts ÷ Volts = Amps
E.g. 1000W ÷ 240V = 4.1Amps
Campers must not forget they may have a battery charger drawing 4-5 Amps, and or a water heater using 8 Amps without calculating other appliances.