Frequently Asked Questions

Polychlorobiphenyl (PCB), commonly known as pyralene, is agroup of substances considered to be hazardous waste, which can be found in a significant percentage of equipment such as transformers or capacitor banks, among others. It has traditionally been used in industry, especially in electrical insulation and for cooling of certain types of electrical transformers.

Following confirmation by the scientific community in the 1960s of their low biodegradability and capacity for bioacummulation in fatty tissues, the potential risk to human health (PCB has been catalogued as carcinogenic) and the environment was made clear, and a process for regulating and banning its use began.

In accordance with Royal Decree 228/2006 [PDF], which amends Royal Decree 1378/1999, dated 27 August, and lays down measures for the disposal and management of polychlorobiphenyls, polychloroterphenyls and the equipment in which they are found, the owners of PCB and of equipment that contains or may contain PCB are under the following obligations:

  • Check and certifythe existence of PCB in dielelectric oils or other liquids, by taking samples and conducting chemical analyses, which will be entrusted to Authorised Control Bodies or Government Affiliations in the field of the environment, whenever necessary. These analyses must be completed before 31 December 2008, in accordance with the schedule envisaged in legislation.
  • Hand over the PCB, used PCB and equipment containing PCB to an authorised waste manager when this needs to be decontaminated or eliminated.
  • Eliminate or decontaminate leaking equipment that contains or might contain PCB as soon as possible.
  • Eliminate any equipment that has reached the end of its service life and might contain PCB, proceeding as follows:
    • Option 1: Conducting a chemical analysis:
      • If the PCB concentration is equal to or more than 50 ppm, hand it over to an authorised PCB manager for disposal.
      • If the PCB concentration is less than 50 ppm, it must be managed in accordance with used industrial oil legislation.
    • Option 2: Without conducting a chemical analysis:
      • In this case, the owner must hand it over to an authorised manager so that it is eliminated once and for all as equipment containing PCB.
  • Decontaminate or eliminate electrical transformers with a PCB concentration of more than 500 ppm, other types of equipment with a PCB concentration of equal to or more than 50 ppm and contained PCB before 1 January 2011.
  • Draw up an inventory of equipment containing PCB.
  • On an annual basis, declare the inventoried PCB equipment, the plans to decontaminate or eliminate them and identified equipment that has already been decontaminated or eliminated to the regional governments, providing the necessary supporting documentation.
  • Label and mark all owned equipment that is inventoried.

Equipment containing PCB liquid must be decontaminated or eliminated in accordance with the final schedule established in Royal Decree 228/2006 [PDF]


  • Unknown construction date: Before 1-1-2007
  • Construction date before 1965: Before 1-1-2007
  • Construction date between 1965 and 1969 (both inclusive): Before 1-1-2008
  • Construction date between 1970 and 1974 (both inclusive): Before 1-1-2009
  • Construction date between 1975 and 1980 (both inclusive): Before 1-1-2010
  • Construction date after 1980: Before 1-1-2011

The equipment must be decontaminated or eliminated in accordance with the following years and minimum percentages, in relation to the total amount in weight (solid plus liquid) that it contains at the start of each year:


  • Year 2006: 20%
  • Year 2007: 25%
  • Year 2008: 33%
  • Year 2009: 50%
  • Year 2010: 100%

This obligation is legally binding on installation owners, and if they keep such substances after the aforementioned dates it will be a cause for penalty.

The final stage of the pyralene elimination process must take place outside national soil. Apart from delaying the process, this points towards possible market saturation and the consequent increase in cost, since the aforementioned deadline applies to all EU countries.

Iberdrola therefore recommends that you start the process to eliminate this substance as soon as possible.