Clauses in contracts whose purpose is to exclude liability incurred by the insured from cover are valid, without the person subject to compulsory insurance being exempted from this obligation in the cases set out below:
1° As a result of damage caused by the vehicle when it is transporting sources of ionising radiation intended for use outside a nuclear installation, if the said sources caused or aggravated the loss;
2° paragraph repealed.
3° In respect of damage caused by the vehicle when it is carrying flammable, explosive, corrosive or oxidising substances and in connection with which the said substances would have caused or aggravated the loss; however, non-insurance may not be invoked in respect of the carriage of oils, mineral spirits or similar products not exceeding 500 kilograms or 600 litres, including the supply of liquid or gaseous fuel required by the engine;
4° in respect of loss or damage occurring in the course of events, races, competitions or their trials, which are subject to prior authorisation by the public authorities under the regulations in force.