Why PCB Testing Is Still Important for Aging Transformers

Polychlorinated biphenyls (PCBs) have not been manufactured in the United States since the late 1970s, but they may still be present in older transformers and other oil-filled electrical equipment. Some units were originally filled with PCB-containing fluids, while others may have been contaminated through historical servicing practices, shared processing equipment or replacement oil.

Because a transformer’s age and maintenance records cannot always confirm whether PCBs are present, laboratory testing remains an important part of maintaining aging equipment. Testing is the only reliable way to determine the PCB concentration in a mineral-oil-filled transformer.

PCB Testing Is Essential Before Maintenance Begins

PCB testing is especially important when maintenance or repair work will require transformer oil to be removed, handled, filtered or processed. This may include:

Knowing the PCB concentration before work begins helps determine the precautions, equipment, handling procedures and disposal requirements that may apply. It also allows the service provider to plan the project properly before crews and equipment arrive on site.

Without current PCB results, maintenance may be delayed while testing is completed. More importantly, unknowingly handling PCB-containing oil could contaminate hoses, pumps, tanks, processing equipment or replacement fluid.

Older Transformers May Contain Unexpected PCB Contamination

A transformer does not have to have been originally designed for PCB fluid to contain measurable PCB concentrations today. In the past, oil, pumps, hoses and processing equipment were sometimes used across multiple units. These practices created opportunities for otherwise non-PCB mineral oil to become contaminated.

Incomplete service records can make the fluid’s history even more difficult to determine. A nameplate, installation date or previous non-PCB label may provide useful information, but these details should not replace laboratory analysis when the oil will be removed or handled.

This is why PCB testing remains relevant for older units—even when the transformer has operated for years without an identified PCB concern.

Results Help Determine the Appropriate Procedures

PCB concentration can affect how transformer oil and associated materials must be managed. Under federal regulations, used oil containing PCBs at concentrations of 50 parts per million or greater is subject to specific requirements under the Toxic Substances Control Act. State requirements and individual facility procedures may also apply.

Accurate laboratory results can help project teams determine:

Identifying the PCB concentration in advance helps protect personnel, prevents cross-contamination and supports compliance throughout the maintenance project.

Protecting Oil-Processing Equipment From Cross-Contamination

Filtering and reclamation projects require oil to circulate through external pumps, hoses, tanks and processing systems. If PCB-containing oil enters equipment that is not designated for that purpose, the equipment—and oil processed afterward—may become contaminated.

Pre-maintenance PCB testing provides the information needed to select the appropriate equipment and establish handling procedures before the transformer is opened. This protects the customer’s assets, the service provider’s equipment and other transformers that may be serviced later.

PCB Testing Supports Better Maintenance Planning

Waiting until a transformer is already out of service to investigate its PCB status can create unnecessary downtime. Testing during routine transformer oil sampling allows asset owners to document PCB concentrations before a repair or maintenance need becomes urgent.

Maintaining current PCB test results can make it easier to:

For facilities with aging transformer fleets, including PCB analysis within a broader oil-testing program can provide valuable information for both maintenance planning and risk management.

PCB Analysis From MVA Diagnostics

MVA Diagnostics provides PCB analysis of transformer oil using ASTM D4059. Our transformer oil laboratory helps utilities, industrial facilities, power-generation operations and electrical service providers obtain the information needed to make informed decisions about aging transformers.

Whether you are planning transformer repairs, filtering, reclamation, retrofilling or equipment removal, PCB testing can help establish the proper precautions and procedures before work begins.

Planning maintenance on an older transformer? Request a quote for PCB testing before the oil is removed, handled or processed.