FPE Stab-Lok® hazards on multi-wire shared neutral circuits
FPE BREAKERS on MULTIWIRE CIRCUITS - CONTENTS: Latent Fire, Shock Hazards of Multi-wire branch circuits & FPE Stab-Lok® Equipment on multiwire branch circuits that share a neutral wire. Increased hazards at circuits using two-pole FPE Stab lok breakers
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Here we describe the real hazards of multi wire branch circuits and single pole circuit breakers where FPE Stab-Lok® equipment is installed. We define "latent safety hazard."
This document explains the latent electric shock and fire hazards associated with Federal Pacific Electric Stab-Lok® electric panels and circuit breakers. Federal Pacific Electric "Stab-Lok® " service panels and breakers are dangerous and can fail, leading to electrical fires. The problem is that some 240-Volt FPE circuit breakers and possibly also some 120-Volt units simply may not work.
Replacement FPE Stab-Lok® circuit breakers are unlikely to reduce the failure risk of this equipment. We recommend that residential FPE Stab-Lok® electrical panels be replaced entirely or the entire panel bus assembly be replaced, regardless of FPE model number or FPE year of manufacture. We do not sell circuit breakers nor any other products.
Special Notice: Multiwire Branch Circuits - warning: to avoid overheating neutral wire and shock hazards involving multiwire branch circuits, it is important to assure that each of the individual circuits is on opposite poles (in the panel) from the other.
In most panels this is accomplished, in fact forced, by using a 240-V common-trip-tie breaker (ganged together switches) which forces individual circuits onto opposite poles. However in FPE panels, the panel bus design does not provide this assurance. -- Rex Cauldwell
FPE Stab-Lok® Hazards - Single Pole Breakers
It is possible that there are similar failures among single-pole (120V) breakers. At least one case of a single-pole 120-Volt FPE GFCI breaker which failed to trip has been reported.
Furthermore, simply purchasing new circuit breakers of the same type from the same manufacturer may not correct the problem. And only special FPE breakers fit in the FPE "Stab-Lok® " electric panel.
When this issue was examined in the early 1980's, FPE's opinion was that the chances of an overload occurring on only a single pole of a 240-volt breaker were very small. In our view there are some very common real-world examples where single-pole loading in a 240-volt breaker might include failures: multi-wire branch circuits and in electric clothes dryers where one of the heating elements shorts to the steel case of the dryer.
FPE Stab-Lok® Hazards - Latent Safety Hazard Defined
The circuit breakers do not directly cause an electrical fire. Some other failure must occur which in turn causes an overload of the circuit "protected" by the FPE breaker. When the breaker fails to trip in response to the overload it has failed to provide the protection intended, and a fire may result. That indirection is why we call this a "latent safety defect."
Why we call this a "latent safety defect" rather than just "hazardous" or "dangerous" needs more explanation. Unfortunately, some people who stand to face big costs grasp at fine distinctions about the failure mechanism in order to avoid facing the problem.
When a defect is itself likely to cause injury directly, such as live wires poking out of the wall by the bathroom sink, we call it a "hazard."
When a defect does not directly cause the injury or loss, such as a circuit breaker which may fail to trip when something else is causing an unsafe overcurrent, we call it a "latent safety defect.
Either way, it's still a problem that needs prompt attention.
FPE Stab-Lok® Hazards - Case Reports of Failures
Is this a linguistic debate or is it really an issue in the field? You bet it's an issue. Recently during an examination by a Maryland home inspector (citations 4,5 below) an FPE panel, was observed and flagged as a potential hazard which should be remedied. The property owner, concerned about his sale, complained and threatened to sue the inspector. This was not an isolated case.
We were able to provide the inspectors with referral to Dr. Jess Aronstein, an engineer in Poughkeepsie, New York, who in turn provided supporting documentation: reports on this problem, a bibliography, and a press release from FPE.
In another example of the dangers of this "latent safety defect," Dr. Aronstein reported that during a disturbance in a jail, a guard hit a gang-switch in an FPE "Stab-Lok® " load center in the cell block area. The breaker did not trip. Rather, it shorted to ground in the switch, blowing a hole in the cover plate. (Citations 6,7)
Building inspectors and renovators often face the discovery of a product which is potentially harmful, which should be replaced, but for which there is little public documentation to justify their position.
Disagreement among people affected by this issue means that it's necessary to be able to cite actual research and actual real-world fire and failure reports.
Continuing to collect and provide FPE Stab-Lok® field reports, we invite readers, building owners, inspectors, and electricians, to report their experience with this equipment - see REPORT YOUR FAILURE
At FPE FAILURE FIRE PHOTOS we have collected a large number of field reports of failures, fires, overheating, case explosions, and simple failure trip for this equipment.
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Questions & answers or comments about why shared-neutral multiwire electrical branch circuits pose special dangers when powered from FPE Stab-Lok® circuit breaker pairs or two-pole breakers of that design.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Dan Friedman is a building consultant in Poughkeepsie, NY. He served as chairman of both the Education Committee and the national Technical Committee of the American Society of Home Inspectors. For Content Suggestions, Contact information is at his website. Because of website traffic volume, if you are seeking contact to ask a technical question, please handle it by email, not telephone.
Rex Cauldwell: "Safe Wiring Practice," Rex Cauldwell, Journal of Light Construction, letter March 1995, p.6.
Note: as we didn't add this reviewers list until 2007, this list of technical reviewers is incomplete; we have received comments and suggestions
regarding this topic, edits and remarks included, from engineers and management from the US CPSC, electricians (many listed at our
page on field reports of FPE failures), home inspectors, licensed electricians, and electrical engineers, and even a few attorneys and
real estate agents, since 1986. Technical review, critique, content suggestions, questions, or clarifications are invited and
where a contributor wishes, credit and links will be provided to that source. Contact us to provide feedback.
Dr. Jess Aronstein, electrical engineer, Poughkeepsie, NY, forensic engineering services, independent laboratory testing for various agencies firstname.lastname@example.org (independent electrical panel testing, including FPE Stab-Lok® panels, to April 2010)
David Carrier, electrical engineer, 53 Henmond Blvd., Poughkeepsie, NY 12603 845-430-7527 email@example.com (independent electrical panel testing, including FPE Stab-Lok® panels, beginning 2010)
Alan Carson, Carson Dunlop Associates, Toronto, Ontario. Mr. Carson is a home inspection professional, educator, researcher, writer, and a principal of Carson Dunlop Associates, a Toronto home inspection and education firm. Mr. Carson is a past president of ASHI, the American Society of Home Inspectors
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator.
Carl Grasso, Esq., Herzfeld & Rubin, New York, NY. Mr. Grasso is an attorney who managed a plaintiff's class action litigation against Federal Pacific Electric in New Jersey.
William King, US CPSC Director of Electrical Engineering (Ret).
Licensed Electricians: FPE FAILURE FIRE PHOTOS includes electricians who have provided cases and photographs of field failures of FPE equipment at this website.
Homeowners, Home Inspectors, Electricians: FPE FAILURE FIELD REPORTS includes anecdotal field reports provided by a range of contributors including electricians (and some home owners or home inspectors) who have provided cases and photographs of field failures of FPE equipment at this website.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Aluminum Wiring Information WebsiteAluminum Electrical Wiring Hazards and Repairs: in-depth authoritative info, photos, documents including selection of proper vs. ineffective repair methods. E.g.: Ideal 65 "Twister" purple connector fails in field and lab testing with aluminum wire.
2007 FPE Stab-Lok® TECHNICAL REPORT - an updated test report of independent testing (a large 1.2MB PDF file) using a larger pool of FPE Stab-Lok® circuit breakers than the older CPSC and Wright Malta tests found significantly higher failure rates of FPE Stab-Lok® circuit breakers, including a look at critical safety failures (breaker failed to trip at 200% of rated current or jammed) which found up to 80% failure rate for FPE Stab-Lok® GFCI circuit breakers (n=4), 12% failure rate for double pole FPE Stab-Lok® circuit breakers (n=120), and a 1% failure rate for FPE Stab-Lok® single pole circuit breakers (n=345).
1982 Reliance Electric Co. SEC Quarterly Report: Note C. reports litigation between Reliance and UV Liquidating Trust and contends that "... improper and deceptive practices were employed for many years to secure UL listings for Federal Pacific's circuit protective products..."
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