This Agreement does not cover procurement by procuring entities other than a public authority exercising the supply of drinking water or electricity to networks which provide a service to the public, if they produce these services by themselves and consume them for the purpose of carrying out other activities than those described under this Annex under (a) and (b) and provided that the supply to the public network depends only on the entity's own consumption and does not exceed 30 per cent of the entity's total production of drinking water or energy, having regard to the average for the preceding three years, including the current year.