Hello Manuel,
I apologise if I incorrectly assumed that you did not have the necessary skills and knowledge to fit electrical systems. Mty suspicions were raised by your apparent lack of knowledge about the current rating on the RCD, and the fact that you referred to Fuses, when such systems do not use fuses in the consumer unit.
I would be negligent if I continued to offer detailed fitting advice to a person who did not understand the important differences, and may have through ignorance or incompetence produced an unsafe and non-compliant system.
The kit I pointed to is specifically sold for use in caravans, and should contain the correct double pole and rated MCB's If it does not then it contravenes the trades descriptions and electrical equipment regulations. I presume that the company had made all the necessary checks in this matter.
I agree with you that I may have used the word "qualified" in error. Though to be come a qualified fitter one has to demonstrate a satisfactory level of competence. If you have found a qualified fitter has failed to perform to the codes of practice and safety laid down, you should report them to Trading Standards, their regulatory body (IEEE) and HSE.
Ray in his last posting refers to a garage system. As this is fitted a permanent UK supply the MCBs do not need to be double pole. Thus a garage kit is not suitable for caravans, But a caravan kit could be used in a garage, though the price hike for the specialist MCBs is likely to make it prohibitive.
As with any electrical or gas supply work, unless you are fully competent and conversant with e the regulations and testing, such work must be left to the professionals.