PCBs were used as dielectric filler liquids in some types of electrical equipment such as transformers, switchgear, capacitors and in the starter units of fluorescent
lights and fractional horsepower motors. Some equipment is labelled as containing PCBs but if you come across old equipment with no identifying label you should check with:
- your employer; or
- the manufacturer or owner of the equipment.
You should assume that any capacitor or transformer manufactured before 1976 may contains PCBs unless you have information to the contrary. It is also possible that there may
be PCBs present in capacitors and transformers manufactured between 1976-1986. Even if the PCBs have been replaced by another liquid, significant amounts of PCBs may still be
present. PCBs may occur as contaminants in the oil used in oil-filled electrical equipment. Always check with your employer if you are in any doubt. Well into the 1970s,
polychlorinated biphenyls (PCB)s were often used as a dielectric fluid since they are not flammable. However, they are toxic, and, under incomplete combustion, can form highly
toxic products such as furan. Starting in the early 1970s, concerns about the toxicity of PCBs have led to their being banned in many countries.Today, nontoxic, stable
silicone-based or fluorinated hydrocarbons are used, where the added expense of a fire-resistant liquid offsets additional building cost for a transformer vault. Natural or
synthetic esters are also becoming increasingly common as alternatives to naphthenic mineral oil. Esters are non toxic, readily biodegradable, and have higher flash points
than mineral oil.
For information on the handling and disposal of PCBs see Waste Management Paper No 6 - Polychlorinated biphenyls (DoE 1994, available from HMSO) or contact your local Waste
Regulation Authority (listed in your local telephone directory) or the Department of the Environment Enquiry Unit, 2 Marsham Street, London SWIP 3EB (Tel 0171 276 3000).
The National Association of Waste Disposal Contractors (NAWDC) will be able to give you a list of contractors who can handle PCBs and PCB waste. Their address is
Mountbarrow House, 6-20 Elizabeth Street, London, SWIW 9RB.