Key takeaway#

On 31 December 2025, the EU deadline for taking PCB-contaminated transformers out of use expired. The line that triggers the duty is 50 mg/kg — not the 500 mg/kg decontamination trigger many asset owners remember from the 1996 Directive. A transformer above 50 mg/kg that is still in service today is in breach of the POPs Regulation, and the duty does not lapse with the date: the unit must come out of service as soon as possible. Below: the three concentration bands and their duties, a worked example, and the laboratory detail that decides the borderline cases.

One measurement decides everything#

PCB was the dominant non-flammable dielectric fluid for transformers until its use in new plant and equipment was banned by international agreement in 1986 (IEC 60422:2024, Clause 7.18). Forty years on, the issue has not aged out of the fleet. A mineral-oil transformer built before the mid-1980s can still carry PCB — either as residue of the original fluid or as cross-contamination from shared handling infrastructure: tankers, filtration rigs, reclamation plants. A unit that is mineral-oil on paper can be PCB-containing in law.

Whether it is, is decided by one number: the measured total PCB concentration. Age and nameplate only tell you who should test first; every duty keys to the measurement. And keep the two small numbers apart: the acceptance criterion for new oil — not detectable, below 2 mg/kg (IEC 60296:2020, Tables 3 and 4) — is a product specification. The legal floor is 50 mg/kg, and the decision flow around it looks like this:

Your obligations, band by band#

Read off the band your measured concentration falls in, then read across.

Two volume thresholds sit behind the table, and they must not be merged. The inventory and labelling duties apply once a unit holds more than 5 dm³ of PCB-containing fluid (96/59/EC, Art. 4(1)). The removal-from-use duty applies already above 0.05 dm³ (Reg. (EU) 2019/1021, Annex I) — in practice, every transformer. Note also what fluid replacement is: where decontamination is performed by replacing the fluid, the replacement must meet the conditions in Art. 9(1)(b)–(d) — the replacement fluid must entail markedly lesser risks, the replacement must not compromise the subsequent disposal of the PCBs, and the unit must be re-labelled. Replacing the fluid is a way of meeting the decontamination duty, not a shortcut around it.

A worked example#

A pre-1986 mineral-oil distribution transformer is sampled. The certificate reads PCB = 120 mg/kg (Method A). That places it in the 50–500 mg/kg row of the table:

• It is legally PCB-containing. Sitting "well under 500" changes nothing.
• It holds far more than 5 dm³ of oil, so it must be inventoried and labelled.
• The removal duty applies, and the table's deadline has expired — the unit should already be out of service and on its way to decontamination or disposal.
• Its drained oil is POP-waste and must be consigned as such.

The reading "only 120 — well under 500, keep it running" is the exact error the band structure exists to prevent.

How the run-to-end-of-life option disappeared. Directive 96/59/EC originally allowed a transformer in the 50–500 mg/kg band to stay in service and be disposed of at the end of its useful life instead of being decontaminated (Art. 9(2)). That allowance is the source of the persistent belief that a lightly contaminated unit may quietly run on. The POPs Regulation closed the route in 2019: its PCB entry opens "without prejudice to Directive 96/59/EC" — the Directive's duties remain in force as a floor — and then lays an absolute removal date on top (Reg. (EU) 2019/1021, Annex I). The 500 mg/kg line still sets the decontamination standard; the phase-out duty begins at 50 mg/kg.

Does the unit's age matter in law? No — the duties key to the measured concentration, not the year of manufacture. Age only tells you who should test first.

The deadline has passed — what now?#

The date was a cut-off, not an expiry of the obligation. A unit above 50 mg/kg holding more than 0.05 dm³ of fluid should already be out of service, and the requirement now reads "as soon as possible" — equally for both contaminated bands. The practical response: pull the certificates you hold, measure where none exists, and plan removal and treatment for anything above the floor.

The law names the method#

Few asset owners know that the 50 mg/kg waste limit comes with its own measurement instruction. Footnote 3 to the PCB row in Annex IV of the POPs Regulation states that the calculation method laid down in EN 12766-1 and EN 12766-2 shall apply (Reg. (EU) 2019/1021, Annex IV). The classification method is not the laboratory's free choice — the law names it.

That matters, because EN 12766-2 contains two calculation procedures which, in the standard's own words, "shall not be confused" (EN 12766-2:2001, Clause 4):

• Method A quantifies the full chromatographic congener pattern. For commercial samples — including insulating oils — it uses the "All Probables" data set (Clause 4.1.2). It is also the method behind an IEC-framework certificate: IEC 61619, the method IEC 60296 and IEC 60422 reference for insulating liquids, is identical to EN 12766-2 Method A (IEC 60422:2024, Clause 7.18).
• Method B sums six indicator congeners — IUPAC 28, 52, 101, 153, 138 and 180 — and multiplies by a factor of exactly five. The factor is an average, derived from the congener content of European waste materials over some fifteen years (Clause 4.2.1 and its NOTE) — not an exact relationship for any single sample.

The UK foreword to the standard adds the warning that matters at the legal floor: Method B may allow samples that should be classified as PCB to escape classification.

Near 50 mg/kg, the precision data makes the same point in numbers. Method B's between-laboratory reproducibility at 50 mg/kg is 22.5 mg/kg (EN 12766-2:2001, Table B.1) — an uncertainty band of nearly half the threshold. Method A's reproducibility is R = 2 + 0.25·x — roughly 14.5 mg/kg at the same level. Close to the floor, the calculation method, not the transformer, can decide which side of the line the certificate lands on.

What a usable certificate must show#

Three checks before anyone acts on a PCB number:

1. The method — including the calculation procedure. EN 12766-2 requires the report to state "Method A – All Probables", "Method A – All Possibles" or "Method B" (Clause 6). A bare "PCB = 42 mg/kg" cannot be compared to the 50 mg/kg floor.
2. The reporting limit for the actual sample — not the standard's nominal value. Matrix and sample size move it.
3. The accreditation scope — the laboratory's ISO/IEC 17025 accreditation must cover PCB in oil. Without it, the certificate is informally useful but weak in front of a regulator.

TriboTech's analysis reports go one step further: we report both the Method A and the Method B result for the same sample. Near the 50 mg/kg floor, that pair is the documentation. If both methods land on the same side of the line, the classification is robust to the choice of method. If they straddle it, the certificate itself shows the result is a margin-of-error case — and the Method A figure is the one to act on.

The Danish layer#

In Denmark the framework is implemented by BEK nr. 1144 af 05/11/2024, in force since 1 January 2025, which replaced BEK nr. 47 af 12. januar 2016 (§ 19). The structure mirrors the Directive: the 0.005 % definitional floor (§ 2, nr. 1, litra d), labelling of equipment holding more than 5 dm³ (§ 7, stk. 1), notification of the authorities (§ 10), and mandatory decontamination above 0.05 % with the objective of bringing the content below 0.05 % (§ 12). Its Bilag 2 prescribes EN 12766-1/-2 and IEC 61619 as the reference analysis methods — the same methods the POPs Regulation names. One point deserves attention: the removal-from-use date is carried by the POPs Regulation itself, which applies directly in Denmark; where the bekendtgørelse's end-of-life wording for the 0.005–0.05 weight-% band (§ 13) appears to differ, the Regulation governs.

Send us the certificate#

If you hold a PCB certificate you are not sure how to read — or a pre-1990 unit with none at all — get in touch. We will place the result in the right band and tell you what, if anything, you need to do. The same applies if you are planning a handover, retrofill or scrapping where the PCB documentation has to be in place before the decision is made.

If the worry that brought you here is PFAS rather than PCB — "is silicone oil a PFAS?" — the short answer is no, and the long answer is in our PFAS article. The full documentation picture across contaminants is in our guide to documenting transformer-oil contaminants.