Electrical Panel Interior Hazards for Electrical & Home Inspectors
ELECTRICAL PANEL INTERIOR HAZARDS - CONTENTS: What to Look for Inside the Electrical Panel as Immediate Safety Concerns - Hazards to electrical inspectors that lurk inside the electrical panel. How to spot signs of water leaks into electrical equipment; How to inspect electrical panels for overheating, melting, shorts, arcing - visually; Signs of burned or overheated wires in electrical panels. Identify unsafe or unreliable electrical panel brands, models, or components, FPE, Zinsco, aluminum wiring. How to spot extra-risky equipment or conditions during electrical panel inspections
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How to inspect the interior of an electrical panel: this article discusses inspection procedures & safety hazards inside residential electrical panels - special concerns to inspectors and electricians.
We suggests safety procedures for the electrical inspector, home inspector, or other professionals who examine residential electrical systems.
What to Look for Inside the Electrical Panel as Immediate Safety Concerns to the Inspector
These electrical inspection suggestions are not a complete inventory of all electrical safety procedures nor of all electrical components that should be inspected; these notes focus on identification of conditions that may present special electrical hazards for the electrical inspector. Contact Us by email to suggest changes, corrections, and additions to this material.
Fatal Shock Hazard Warning: Inspecting electrical components and systems risks death by electrocution as well as serious burns or other injuries to the inspector or to others. Do not attempt these tasks unless you are properly trained and equipped.
Evidence of water entry inside the electrical panel (photo at below right) means that circuit breakers may be corroded and won't trip, connections may be unreliable, neutral or ground connections may be lost, and touching the equipment could be dangerous.
Evidence of overheating, melting, burnups inside the electrical panel (photo at below right) - this was the ground that overheated when there was no neutral connection in the sub panel and neutral and ground buses were improperly bonded.
[Click to enlarge any image]
Evidence of missing bonding or improper bonding (such as ground to neutral in a sub panel) may combine with evidence of overheating (photo above left) to indicate improper wiring, damaged equipment, and unsafe conditions.
The loss of netural connection in a garage sub panel (the steel screw bound in the aluminum neutral lug in photo at below right) combined with improper bonding (ground to neutral - red wire in photo at below left) and other conditions to shock an owner when he touched his metal workbench. See Case History:Loss of Neutral Shocks Homeowner for details of this case.
Evidence of burned or overheated wires or damaged circuit breakers, aluminum wiring, faulty equipment, mis-wiring, linking, bus and bonding defects, and many other defects form part of the electrical panel inspection and are described outside of this safety procedures article -
see ELECTRIC PANEL INSPECTION
In addition to examining the electrical panel before touching it, looking for dangerous conditions like water, rust, sheet metal screws, rats, and blocking client access, the inspector should also recognize that certain brands or models of electrical equipment are known to be unsafe and may be dangerous to inspect or operate.
Federal Pacific Electric Stab-Lok equipment includes breakers which remain internally "on" when switched "off", as well as too often failing to trip off in response to an overcurrent, and which have been reported to result in electrical arc explosions when manually or otherwise exercised.
Zinsco: Similar bus burnups and electrical arc explosions have been reported regarding Sylvania/Zinsco electrical panels.
Contact Us by email to add field reports of problems regarding these or other electrical products.
Opening the electrical panel to examine overcurrent devices - fuses or circuit breakers, is discussed
Do not try to "exercise" the breakers in these panels. Turning the circuit breaker on and off in an FPE Stab-Lok panel can actually increase the risk of a future failure to trip. We also have field reports of electrical arc explosions when these breakers have been switched on or off. Some examples are included in this series of electrical safety articles.
The inspector is not required to insert anything, finger, screwdriver, probe, into the electrical panel. The required inspection is visual. Observe. However an inspector is of course permitted to perform other tests or services which s/he chooses to provide (presuming s/he is qualified, trained, and that three are no conflicts of interest).
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Questions & answers or comments about shock and electrocution hazards when touching electrical equipment during an inspection.
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Electrical shock injury statistics: www.healthatoz.com - September 2008;
High-tension current generally causes the most serious injuries, although fatal electrocutions may occur with household current (e.g., 110 V in the United States and Canada and 220 V in Europe, Australia, and Asia). Contact with alternating current at 60 cycles per second (the frequency used in most US household and commercial sources of electricity) may cause tetanic skeletal muscle contractions, preventing self-release from the source of the electricity and thereby leading to prolonged exposure. The repetitive frequency of alternating current also increases the likelihood of current flow through the heart during the relative refractory period (the "vulnerable period") of the cardiac cycle. This exposure can precipitate ventricular fibrillation (VF), which is analogous to the R-on-T phenomenon.-- circ.ahajournals.org - September 2008
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. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: firstname.lastname@example.org
"Frequency of Occurrence and Sources of Rust and Corrosion in Electrical Panels," Daniel Friedman, IEEE HOLM Conference, Philadelphia PA, 1992 - see ELECTRIC PANEL RUST for an online version of this article.
Jim Simmons: Personal communication, J. Simmons to Daniel Friedman, 9/19/2008. Photographs contributed to this website by Jim P. Simmons, Licensed Electrician, 360-705-4225 Mr. Electric, Licensed Master Electrician, Olympia, Washington Contact Jim P. Simmons, Licensed Master Electrician, Mr. Electric, 1320 Dayton Street SE
Olympia, WA 98501, Ph 360-705-4225, Fx 360-705-0130 email@example.com
Kenneth Kruger: Original author of the sidebar on testing VOM DMM condition: Kenneth Kruger, R.A., P.E. AIA ASCE, is an ASHI
Member and ASHI Director in Cambridge, MA. He provided basis for this article penned by DJ Friedman.
"How to Use DMM's Safely," Leonard Ogden, CEE News, 888 Seventh Ave., New York, NY 10106, Dec 1990 p.10.
Dr. Jess Aronstein, consulting engineer, Poughkeepsie NY, 1991 firstname.lastname@example.org
Rex Cauldwell, master electrician and contributor to the Journal of Light Construction on electrical topics
New York State Central Hudson Gas and Electric Company, G&E/1-2/85 consumer safety pamphlet
American Society of Home Inspectors, ASHI Training Manual, Al Alk -[obsolete, and includes unsafe practices-DF]
"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.
"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.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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)
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
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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.
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