Pre-1970 Federal Pacific Electric FPE Stab Lok circuit breakers and electrical panels - Risk Assessment
FPE Pre-1970 STAB-LOKS OK? - CONTENTS: Are older "pre-1970" FPE-Stab-Lok® circuit breakers and panels safer and more reliable than later models? Photographs of older (pre-1970) FPE circuit breakers, labels, and bus designs provide means to identify this equipment even if labels are missing or painted-over
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This document discusses the safety of older, "Pre-1970" Federal Pacific Stab-Lok® Circuit Breakers & Electric Panels in buildings.
Here is information for building inspectors, home buyers, home owners, electricians exploring the background of possible hazards associated with Federal Pacific Electric Stab-Lok® circuit breakers and service panels.
Safety of Older FPE Stab-Lok® Electrical Panels & Breakers
Watch out: Safety warning: while opening the hinged door provided for consumer use to access
and reset the breakers is permitted, because there is risk of dangerous or even fatal electric shock in any electrical panel interior, only an expert should actually remove the front cover.
Question: Are pre-1970 FPE Stab-Lok® circuit breakers as unsafe as the later models?
As I searched InspectAPedia I see statements that ALL FPE breakers and panels must be replaced. However the vast majority, if not all of the problem reports that I have read are of FPE circuit breaker equipment installed in the 1970's early 1980's.
We live in a neighborhood built in the 1950's and my wife is a realtor. The houses here have the old 100amp brown FPE breakers with copper split busses. Is there data and problem reports that supports a higher than normal industry failure rate for 1950s manufactured FPE breakers and panels? Or is this a "guilty by 1970s association so all FPE breakers and panels are bad" thing.
-- Loren Schiele. BS EE
The photos below, courtesy of electrical panel researcher David Carrier, show older FPE Stab-Lok® circuit breakers that include the use of some copper components.
This 40-Amp two-pole circuit breaker, FPE Catalog No. 240, lacks an internal common trip mechanism, relying on mechanical linkage between the two breaker halves. Additional photos of FPE Stab-Lok® circuit breakers of various vintages including this pre-1970 set are at FPE BREAKER ID PHOTOS.
Only Limited Testing of Older Pre-1970 Equipment
Among the more than 1600 FPE Stab-Lok® breakers tested to date, there are too few of those with the "old" construction (brown case and/or hexagonal handle) tested to date to conclude that they are substantially different in performance.
Lack of Common Internal Trip Mechanism in Older Circuit Breakers
One significant difference is that the early 2-pole FPE Stab-Lok® breakers had linked handles but lacked an internal common trip mechanism.
The lack of a common-trip mechanism is today considered less safe, which is why the standards were changed to require it. At the same time, these do not have the jamming problem of the later FPE 2-pole breakers that is specifically attributed to the common trip mechanism.
Degradation of Electrical Equipment With Age
The FPE Stab-Lok® performance problems were not restricted to the 1970's and later production. While one could postulate that the quality control, tooling, etc. at the plant degraded with time, so that the early FPE Stab-Lok® breakers might be better than the average FPE, that is in part balanced by the fact that mechanical devices generally degrade with time, and the original FPE Stab-Lok® breakers are now headed toward 60 years in service.
There is also the question of added circuits and replacements
Many of the original panels are likely to have some Stab-Lok® breakers of more recent manufacture.
What is their performance?
Where do you get "good" Stab-Lok® breakers for future additions or replacements?
Busbar Contacts in Older FPE Stab-Lok® Panels
As for the busbar contacts, there are no problems that we know of with the original copper busbar (with openings punched in) and the heavy "stab" of the full-width breakers.
The split bus design (if that is what you have, as mentioned in your EMail) has adverse safety issues, however, regardless of brand of electrical panel involved.
Further Study Needed on Older FPE Equipment - Rotating FPE Breaker Replacement & Free Testing Project
If there are enough interested and cooperative homeowners in the neighborhood, perhaps you could organize a rotating breaker substitution system that would allow Dr. Aronstein or our collaborating test engineer David Carrier to test the breakers and return them, so as to obtain the performance data that all of us are interested in.
Watch out: preliminary field and independent lab test data indicates high failure rates (breakers don't trip in response to over-current following standardized tests) for replacement circuit breakers for FPE panels.
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Questions & answers or comments about the performance & safety of olde3r FPE Stab-Lok® equipment - made before 1970.
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Thanks to reader Loren Schiele,
BS in Electrical Engineering, for discussing older FPE Stab-Lok® equipment and its safety concerns - M1y 2010
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
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