Caravans and Motorhomes have two power circuits - 12 volt for most lights and some 12V appliances, and 240V circuits for your power points like those at home.
But the 240V is not the same as at home because it is not permanently hardwired.
In your house every circuit starts from your fuse box. Which is normally located at the on the side of the house.
Each circuit has a limited capacity because the wires running through your walls have a limited capacity.
With your RV, the limit starts from where your power cord is connected to the power source e.g. at a caravan park.
All Caravans/Motorhomes accept incoming power through a 15amp extension cord.
One cord provides power for one circuit within your RV. In many cases 15amp's will not be enough, so a second and sometimes even a third circuit is required.
The 15amp extension cord allows 1.5 times the current that a standard household 10amp cord can handle.
Heavy duty 10amp cords are not the same and cannot be used to bring power to your RV. 15amp sockets and plugs have a larger earth.
The larger pin is not there to provide a greater earth, but it is there to prevent you connecting a 10amp extension lead to a 15amp plug.
Rather than having just one really long extension lead that will suit every location, why not also carry a shorter one as well, for convenience you ask?
It is now illegal to join two cables to your RV to give greater length as this may jeopardise the operation of your RCD, the life saving device that will trip if YOU become the earth.
There will be times when a 15amp power point is not available to connect to, like when parking at a friends house or even at home.
This has in the past caused dangerous practices and modifications that are no longer necessary.
There are a couple of products that allow you to connect a 15amp power cord to a normal 10amp power point.
They are fitted with a circuit breaker to prevent more than 10amps being carried through from the supply power point.
The PODSAFE and AMPFIBIAN are weather rated and are specially made for the RV market, while the ELECTUS is made with tradesman in mind and must be kept out of the weather.
Replacing or adding power points or switches.
The 240volt switches and power points used in Recreational Vehicles differs from households in one very important way. All switches and power points must be double pole. This is by law, and for your safety.
This means that the switch breaks the circuit of the Active and the Neutral wires when the switch is set to OFF. In normal household switches and power points, only the Active wire (Red or Brown) is disconnected.
This is the reason you cannot use single pole switches or power points.
Article by Peter Smith - Caravans Plus