What is a "Stab-Lok" Breaker?
Stab-Lok is a brand name of circuit breaker and electrical panel designed and manufactured by Federal Pacific Electric (FPE). In Canada, these were mostly sold under the name "Federal Pioneer". They were installed in homes from around 1950-1990. The panels are no longer made, but replacement breakers are still in production. The "Stab-Lok" brand name is still used, although the equipment is now made by a different company.
Are They a Dangerous?
Yes. Stab-Lok breakers have a well-documented history of poor reliability, and have been shown in independent testing to have far higher than average failure rates. Known issues include:
Failing to trip soon enough (a circuit can remain overloaded for several minutes)
Failing to trip at all (the circuit is never broken, and continues to overheat)
Sub-par connections between breaker and panel can cause overheating
All of these scenarios are dangerous and present a significant risk of electrical fire. A 2017 research paper showed that around 1 in 3 breakers are defective and run the risk of failure or electrical fire.
Around 1 in 3 breakers are defective and run the risk of failure or electrical fire.
How Big is The Problem?
Unfortunately, there is very little data available for Canada. According to a 2012 research paper, there are an estimated 2,829 residential electrical fires per year in the USA associated with Stab-Lok breakers. That is approximately 2.5% of all residential electrical fires. The paper estimates FPE Stab-Lok breakers to be responsible for 13 deaths and up to $40M in property damage each year in the USA.
FPE Stab-Lok breakers are estimated to be responsible for 13 deaths and up to $40M in property damage each year.
How Did They Pass Certification?
The short answer is: they didn't. Underwriter's Laboratories (UL) was the body responsible for examining the breakers when they were first designed. Once UL inspected the first batch of breakers, FPE became responsible for testing and certifying its own product. UL would periodically send an auditor to the factory to check that tests were being conducted properly.
A UL sticker on a breaker indicated to electrical inspectors that the product met the required safety standards. Once the sticker was applied, there was no reason for anyone to suspect the product might be defective. FPE was fraudulently applying UL stickers to their products for decades.
A Multi-Decade Scam
Early Warning Signs
As early as 1956, UL sued FPE to prevent them from fraudulently labelling defective breakers with UL stickers.
In 1979, FPE was purchased by Reliance Electric, a subsidiary of Exxon Mobil. Reliance quickly reported to the Consumer Product Safety Commission (CPSC) that there was an issue with the reliability of some of their commercial and industrial breakers.
In 1981, the CPSC conducted their own testing of the breakers and verified the issue. FPE claimed that the issue was "testing specific" and would not occur in the real world.
In 1982, FPE issued a recall notice for a few select industrial and commercial breakers. By this point, most of their products had been de-listed by UL, meaning they were no longer eligible to receive certification stickers.
The Cover Up
In 1983, the CPSC officially closed their investigation, citing insufficient data to "rigorously prove a direct relationship between the defective breakers and specific incidents of fire, injury, or death". The agency claimed that it lacked funding to collect the necessary data.
FPE then took legal action to block the CPSC from responding to any Freedom of Information Requests pertaining to the investigation, effectively blocking members of the public from learning the results.
The Fallout
By 1986, the FPE Stab-Lok design and brand name had been sold off by Exxon, and the company stopped producing circuit breakers. FPE no longer exists as a public-facing company. A legal entity registered to an attorney's office exists to handle the remaining work associated with the lawsuits.
In 1999, an article was published in the monthly newsletter of the International Association of Electrical Inspectors (IAEI News). The article claimed that if the breakers had a UL sticker, they were safe. The article was written by the former quality manager of FPE. It has since been removed from the IAEI archives.
In a 2002 class action lawsuit, a New Jersey court found that FPE had committed fraud by misrepresenting to the public that their breakers met the applicable safety standards, when they in fact, did not.
Was There a Recall?
Sort of. In 1982, FPE recalled some of their commercial and industrial breakers, but never any of the residential models. In the 1990s, Federal Pioneer issued a recall for one specific 15A breaker made between 1996-1997. There has never been a recall for most residential Stab-Lok breakers.
Who Makes Them Now?
Stab-Lok brand circuit breakers are still manufactured and sold in Canada by Schneider Electric. According to a 2017 research paper the internal mechanisms of these new breakers are virtually identical, and failure rates are similar to the original FPE breakers.
How Are They Still Being Sold?
In Canada, the breakers are certified by the Canadian Standards Association (CSA). The variant sold in the USA are listed by Intertek. Underwriter's Laboratories (UL) is no longer involved with testing or certification of these products.
Similar Testing
Testing procedures have not changed meaningfully since the original CPSC investigation. CSA or Intertek conduct initial testing, but most of the quality control is left up to the manufacturer, with periodic visits by an auditor to the factory to ensure compliance.
Technical Requirements
In order to meet safety standards, breakers must trip at or below 135% of their rated capacity. However, there are additional testing requirements, at 200% or even 300% of rated capacity. A 2006 research paper states that manufacturers are believed to be testing the breakers only at one current level (200% or 300% of capacity). They are then making the assumption that the breakers would also trip at the lower 135% current. The paper states:
It is reasonable to question that assumption... test data clearly demonstrates that passing the [200% or 300% test] does not assure that a breaker would pass the basic 135% overload trip requirement.
What Can I Do?
If you have a Stab-Lok electrical panel and breakers, you should consider replacement. Although there has been no formal recall for most of these products, peer-reviewed research has shown that they are unreliable, and are linked to a substantial number of fires and deaths each year.
A visual inspection of the panel and breakers by an electrician does not provide any useful information, since the defects in the breakers are internal.
Key Points
Stab-Lok breakers and panels were installed from around 1950-1990.
The company was found guilty of fraud for labelling defective breakers as safe.
Around 1 in 3 breakers are defective.
Replacement breakers are still being made by a few different companies.
Research shows that these new breakers are virtually identical to the old ones.
Stab-Lok breakers present an increased risk of electrical fire.
Stab-Lok breakers are thought to be responsible for around 13 deaths and $40M in property damage each year in the USA.
If you have a Stab-Lok panel/breakers, consider replacement.
Acknowledgements
This post owes its existence to the diligent research conducted by Jesse Aronstein, Ph.D., P.E. His wealth of research, along with a valuable collection of links, documents, and resources, has been indispensable. For further reading, you can access his work here.
Special thanks go to Richard Lowry, Ph.D., for co-authoring with Dr. Aronstein in estimating fire losses related to FPE breakers.
I'd also like to extend my gratitude to Daniel Friedman of Inspectapedia for his extensive work on this topic. Thank you for all your contributions.