If the devices provided for in articles R. 4534-96 and R. 4534-97 are not installed, or if work platforms or any other similar devices suspended from lifting equipment are not used, the following shall be installed:
1° Either canopies, fans or floors capable of preventing a free fall of more than three metres;
2° Or nets, or any other device of at least equivalent elasticity, capable of preventing a free fall of more than six metres.