Electrical Circuit Breaker Failures

Photos of Burned Circuit Breaker That Failed to Turn Off
- Examples of unsafe electrical circuit breakers: failure to turn off, fires, burn-ups
Questions & Answers about unsafe electrical circuit breakers and types or modes of circuit breaker failures
References

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Electrical Circuit Breaker Burns, Fails to Trip, Continues to Conduct Power: this document demonstrates detection and fire risks of a bad electrical circuit breaker which burned, failed to trip, and remained live in the electric panel.

Electrical Circuit Breaker Failures Detected by Simple Visual Inspection

The example is used to inform electrical inspectors, home inspectors, electricians who inspect building electrical panels for defects. Photographs and comments describe a modern residential electrical service panel with aluminum bus parts which corroded, overheated, and in which a circuit breaker which had burned but was continuing to power the circuit!

You don't need a VOM or digital volt meter to see bad burn ups like this but this failure is a strong recommendation for use of digital multimeters or simple neon testers to confirm that circuit breakers really do turn off the power.

Other critical electrical system failures are explained and photo-documented at Federal Pacific Electric Stab-Lok and Zinsco Electrical Circuit Breaker Failures and Aluminum Wiring Information Website

Full View of Electrical Panel with a Burned Circuit Breaker

On opening the panel, arcing and burn marks were obvious. Note the black stains along the left side of the right-hand bus bar above the highest breaker in the panel.

Note also the corrosion present at the neutral bus and bus bar connector at the panel bottom right corner. This panel was in a wet utility basement of an old house in New York state.

However it did not appear that moisture in the panel from basement conditions was the root cause of overheating and damage. There was not general corrosion throughout the panel. The panel itself was relatively new, less than ten years old.

A Look at the Electrical Panel Center

A look at the center of the panel shows pieces of circuit breaker plastic and other debris that was obviously a product of arcing and burning at one of the circuit breakers.

Close up View of the Electrical Panel Center

A closer look at the same area shows a piece of one of the right-hand breakers sitting atop the lower breaker on the left. Notice the red and white corroded material at the lower right corner of the top breaker. J. Aronstein suggests that overheating in the breaker burned off zinc or other anti-corrosive plating leading to bleed-out of rust particles.

Other breakers in the panel, presumably of the same age, did not show these visual indications of damage.

Burned, arced breaker still in place, still "live"

Finally, shifting the angle and getting some better light on the subject one could see that the lower of the uppermost two breakers in the panel right side had burned badly where it was connected to the aluminum bus of the panel.

It was remarkable that despite severe damage to the breaker and panel bus, the breaker was still conducting current to the circuit connected to it.

During a home inspection inspectors should not touch equipment like this. Using a TIF Instruments Tic Tracer it was possible to confirm live electrical power at various points. Of course, what's called-for is an immediate repair which most likely requires replacement of the bus assembly and breakers if not the whole panel.

Home inspectors are not forensic engineers, but it appears obvious to anyone looking at this equipment in-situ that overheating at the connection of the breaker to the panel bus must have led to arcing, breaker damage, and thus creation of an unsafe condition in which there is very likely no overcurrent protection being provided by this equipment.

You don't need a VOM or digital volt meter to see bad burn ups like this but this failure is a strong recommendation for use of digital multimeters or simple neon testers to confirm that circuit breakers really do turn off the power.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

"Whole-House Systems Approach [to saving on energy costs]", U.S. DOE, describes designing and constructing an energy-efficient home by considering all of the house systems. Original DOE source: www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10370
- "Appliances and home electronics", U.S. DOE on energy savings suggestions
- "Insulation and Air Sealing", U.S. DOE describes how to reduce a home's heating and cooling costs by proper insulation and air leak sealing. Moisture control and ventilation are also discussed.
- "Lighting and Daylighting", U.S. DOE, is a very brief DOE article suggesting how to reduce the cost of lighting in a building
- "Space Heating and Cooling", U.S. DOE, attacks the biggest energy user in buildings, typically about 56% of energy use in a typical home in the United States.
- "Water Heating", U.S. DOE, addresses reducing the cost of heating domestic hot water used for washing and bathing - that accounts for 14-25% of home energy usage in the U.S. and includes
  - "Selecting a Water Heater", U.S. DOE
  - "Energy Efficient Water Heating", U.S. DOE includes suggestions to lower hot water heating costs including reducing hot water usage, lowering hot water temperature, insulating the water tank (nonsense), insulating hot water pipes, installing heat traps on the water heater tank, water heater timers, and drain-water heat recovery systems (possibly not cost effective)
  - "Swimming Pool Heating" cost savings suggestions from the U.S. DOE includes suggestions on using a high efficiency (gas-fired swimming pool heater or heat pump swimming pool heater) or solar swimming pool heater, using swimming pool covers, managing swimming pool water temperatures, and installing a more energy efficient swimming pool pump, or using it less.
"Basic Housing Inspection," US DHEW, S 352.75 U48, p.144, out of print, but is available in most state libraries.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd

Recommended books on electrical inspection, electrical wiring, electrical problem diagnosis, and electrical repair can be found in the Electrical Books section of the InspectAPedia Bookstore. (courtesy of Amazon.com)
Rust and Corrosion in Electrical Panels, A Study and Report on Frequency and Cause for Electrical and Home Inspectors at Residential Electric Panels
"Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
"Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
"How to plan and install electric wiring for homes, farms, garages, shops," Montgomery Ward Co., 83-850.
"Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
"Home Wiring Inspection," Roswell W. Ard, Rodale's New Shelter, July/August, 1985 p. 35-40.
"Evaluating Wiring in Older Minnesota Homes," Agricultural Extension Service, University of Minnesota, St. Paul, Minnesota 55108.
"Electrical Systems," A Training Manual for Home Inspectors, Alfred L. Alk, American Society of Home Inspectors (ASHI), 1987, available from ASHI. [DF NOTE: I do NOT recommend this obsolete publication, though it was cited in the original Journal article as it contains unsafe inaccuracies]
"Basic Housing Inspection," US DHEW, S352.75 U48, p.144, out of print, but is available in most state libraries.
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