Question for the OP. The below quote is in the literature. Does your caravan have a 16 amp or less power supply (PSU)? I ask because I keep finding
these.
It is possible that the 230V mains electrical equipment may not all operate simultaneously. A typical UK motorhome site mains hook up point provides a maximum output of 10 amps and on some continental sites the available output may be as low as 5 amps.
for the electricians: the OP's RV may very well use a 230V AC 16 amp setup.
download and open in Acrobat Reader - go to PDF page 51 (rotate clockwise)
http://assets.swiftgroup.co.uk/swift-group/handbooks/2013%20Owners%20Handbooks/2013%20Van%20Conversion%20Owners%20Handbook.pdfdownload and open in Acrobat Reader - go to PDF page 61 (rotate clockwise)
http://assets.swiftgroup.co.uk/swift-group/handbooks/2013%20Technical%20Handbooks/2013%20Van%20Conversion%20tech%20book.pdf