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Transformer PCBs: A guide for buying and selling

PCBs used to be used in transformer oil. Now, they're banned because of their harmful health effects. Modern transformers contain no traceable amount of PCBs.

Written by:
Nathan Stenzel & Ben Gulick

October 24, 2024

PCB graphic

Once upon a time, virtually all oil-filled transformers contained deadly chemicals linked to cancer.

These harmful chemicals are called PCBs.

What are PCBs?

PCBs (polychlorinated biphenyls) are a man-made chemical used in transformer insulating fluid. They were also used in various coolants, adhesives, fluorescent light ballasts, and other applications. 

Here are some more facts about the scope of PCBs' use:

  • PCBs were used in transformers from the 1930s to the late 1970s
  • An estimated 1.5 million tons of PCBs were created globally
  • Over 600,000 tons of that was produced in the United States
  • Banned by the EPA in 1979

Today, no one builds transformers with PCBs, but it’s still important to avoid them in old units.

So what makes them so dangerous? Why were they used in the first place? And what should you do if you come across a PCB transformer?

What’s wrong with PCBs?

You can think of PCBs like asbestos: great for flame resistance, bad for your health. PCBs made transformer oil less flammable, but they also made it highly toxic. In the short term, PCBs can cause skin irritation, nausea, or even breathing difficulties. Long-term, they can cause cancer, reproductive defects, and liver damage.

Environmental Impact of PCBs

In addition to their dangerous health effects, PCBs negatively impact the environment. They enter the air, water, and soil during their manufacture and use. Unfortunately, they take a long time to break down. So, animals and fish absorb PCBs from water and sediments. Consequently, PCBs begin to accumulate in the food chain. This is why disposal regulations are so strict today: PCBs getting into soil and water can have long-lasting negative effects.

Sign warning of the presence of PCBs in Potomac River
Health Advisory Warning about PCBs at Leesylvania State Park, VA.

PCB Ban

So, in 1979, the EPA banned the use of PCBs. If they were already deployed, transformers with PCBs were allowed to remain in operation. The EPA gradually phased out most industrial uses of PCBs over a five year period. But building new transformers with PCBs ended in 1979. Transformer manufacturers don’t build with PCBs today.

PCBs levels in transformers

The main thing to watch out for is any transformer built before 1979. There’s a good chance that any unit built between 1929–1978 has PCBs.

In 1979, the EPA defined three ranges of PCB contamination: 

  1. PCB Transformer (containing greater than 500ppm)
  2. PCB-Contaminated Transformer (containing 50–500ppm)
  3. Non PCB Transformer (containing less than 50ppm).

Any transformers built today won’t contain any traceable amounts of PCBs. This means it will have less than 2 ppm PCBs. You’ll often find this on the unit’s nameplate:

<ppm PCB highlighted on transformer nameplate

Even though they contain no traceable amount (<2 ppm) of PCBs, many modern transformers still have a blue sticker which says they contain <50 ppm. Don’t let this confuse you: if it was built recently, it won’t contain any traceable amount of PCBs. The sticker is just a leftover from the 1979 EPA ruling.

Blue non-PCB sticker on padmount transformer

Technically, these stickers are unnecessary, though many customers still request them. Once again, transformers built today don’t contain any traceable amount of PCBs.

Maddox transformer tech putting non-PCB sticker on reconditioned transformer

Reconditioned transformers and PCBs

Maddox’s reconditioned units do not contain PCBs. We will not recondition a transformer unless the oil contains no traceable amount of PCBs.

PCB contamination

Maddox also does not test or service PCB contaminated transformers. There’s a simple reason for this: any tools (like oil pumps and hoses) that you use on a PCB contaminated unit will also get contaminated. Reusing those tools then contaminates other transformers.

Disposing of PCBs

If you’re looking to offload a transformer with PCBs, it’s important to do so safely and according to the EPAs guidelines. Maddox does not buy surplus units with PCBs, but we can direct you to the proper channels for disposal. 

Conclusion

It’s important to know the industry standards for PCBs so you understand why transformers are labeled the way they are. You probably won’t run into PCB transformers unless you have older units on site. And here at Maddox, we guarantee all our new and reconditioned transformers are PCB free.

Maddox padmount transformer loaded on truck

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