The identification and selection of external companies by the user company is based on the following three cumulative criteria:
1° The nature of the particular risks associated with the work and likely to affect the safety of the workers present in or near the installation, which is the overriding criterion;
2° The number of employees working or due to work, expressed as an average number of men per day present in or near the installation over a period of twelve consecutive months;
3° The duration of the work to be carried out from the date of consultation of the social and economic committee, as provided for in article R. 4523-8.