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Polychlorinated Biphenyl (PCB) - SAFETY WARNING

Polychlorinated Biphenyl is a significant health hazard and is present in many capacitors made before 1997.
Some television and radio receivers may contain these capacitors, unmarked with any safety warning.

Please read this warning and play safe!


During the 1930s electrical engineers expressed the need for a synthetic electrical insulation fluid for transformer and capacitor installations where fire was a particular hazard. The new fluid had to have the some performance and electrical strength as mineral oil but must be fire-resistant. The resulting fluid was PCB which enabled transformers to be positioned anywhere the engineer wished but, unfortunately, this new coolant (termed ‘Askarel') was environmentally hazardous and in the last ten years many countries have ceased manufacture and use of this liquid.


What are PCBs?

PCBs (Polychlorinated Biphenyl) were widely used as a dielectric fluid in electrical transformers and capacitors. Their manufacture in the USA and the UK ceased in 1977. However, there remain a large number of installations which still contain PCB and more importantly these were not always labelled as containing Askarel as the product was sold under many different Trade Names (see below). In many instances these units were located in low-risk areas where the need for PCB was unnecessary.

Why are they hazardous?

PCB is non-biodegradeable and is persistent in the environment. It con be absorbed through the skin, causing a skin rash called chloracne, liver damage and an increase of the fat in the blood. Appropriate protective clothing must be warn when handling equipment containing PCBs, also when subject to high temperature PCB can produce potychlorinated dibenzofurans (PCDFs) and, in the presence of tri- or tetra-chlorobenzene some polychlorinated dibenzodioxins (PCDDs) can be formed too. Some of these substances are extremely toxic - much worse than PCB - thus PCBs involved in a fire can produce long-lasting contamination of buildings.

What are the Regulations?

The Department of the Environment has published a Statutory Instrument (1986 No. 902) which provides the UK's reponse to an EEC directive published in October 1985 (851467/EEC). This bans the use of PCBs, PCTs (polychlorinated terphenyls) and preparations containing greater than 0.01% PCB or PCT by weight (100 ppm). Transformers and capacitors containing PCBs in use on 30th June 1986 may continue until the end of their service life but may not be sold on the second-hand market. In addition, the disposal of any waste containing PCBs is subject to the control of Pollution Act and where the PCB concentration is greater than 1%, such wastes are also subject to the Special Waste Regulations 1980 made under the same Act. The packaging and labelling of the waste is controlled by the Classification. Packaging and Labelling of Dangerous Substances Regulations 1984. Transport of PCBs is governed by Department of Transport European Agreement 1985, Road Traffic Regulations 1986 No. 195f and Waste Management Paper No.6 published by the DoE. The Central Electricity Generating Board has produced a report reference GS-C3 entitled ‘The Safe Use of Polychlorinated Biphenyl Filled Apparatus’. In addition to these documents customers can obtain useful information from Winders concerning packing and labelling PCB wastes, and will provide the statutory consignment notes for disposal and advise on their use and completion as required.

What can I do with transformers containing PCBs?

Previously the stock answer to this question has been to retro-fill the unit with a non environmentally-hazardous dielectric. However, the process of retro-filling as presently practised in the UK cannot guarantee that the level of PCBs in the dielectric will remain permanently below that defined as non-PCB by the legislation covering PCBs. This is the case even when a second retro-fill is carried out after a period of time. However, where the client fully understands this point, there can be no objection to arranging for retro-filling, particularly where removal of the transformer would be impractical, or as a prelude to disposal of the transformer. A retrofilled transformer should be labelled to the effect that it has been retro-filled but residual PCBs may still be present.

What can I do with capacitors containing PCB?

Capacitors containing PCBs fall into two categories, according to size. Small capacitors were used in fluorescent and other discharge luminaires and with fractional horse-power motors of the type used in domestic and light-industrial electrical equipment. They were not labelled as containing PCBs, although they were normally date-coded, Generally speaking, it must be assumed that capacitors manufactured before 1976 contain PCBs. As a precaution, operatives involved in replacing these capacitors should wear polythene or PVC gloves (not rubber), and these should be put, together with the capacitors and any waste wiping material used to clean the appliance, in a sealed polythene bag. Where large quantities of small capacitors are involved, they should be disposed at in the same way as large capacitors or transformers.

Large capacitors were used for power factor correction and similar duties. More recently manufactured capacitors were labelled as containing PCBs, but it should be assumed that capacitors manufactured before 1976 do contain PCBs.

PCB Trade Names

When PCB was used in transformers and capacitors then, depending on their country of origin the name of the liquid used varied considerably. In order to help the customer, listed below are a number of the more well known trade names which have been used:

I suspect VISCONOL (used in high-voltage caps in TVs with mains-derived EHT) was also PCB.

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