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ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR

AFCIs ARC FAULT CIRCUIT INTERRUPTERS
ALUMINUM WIRING HAZARDS & REPAIRS
AMPS VOLTS DETERMINATION
APPLIANCE EFFICIENCY RATINGS

BOOKSTORE - ELECTRICAL

Cadet & Encore Heater Recall
CIRCUIT BREAKER SIZE for A/C or HEAT PUMP
Classified CIRCUIT BREAKER WARNING
CUTLER HAMMER PANEL FIRE
CONDUIT, ELECTRICAL
CORROSION in ELECTRICAL PANELS

DEFINITIONS of ELECTRICAL TERMS
DIRECTORY OF ELECTRICIANS
DMM Digital Multimeter, How to Use

ELECTRIC HEAT
ELECTRIC METERS & METER BASES
ELECTRIC MOTOR DIAGNOSTIC GUIDE
ELECTRIC MOTOR OVERLOAD RESET SWITCH
ELECTRIC PANEL AMPACITY
ELECTRIC PANEL INSPECTION
ELECTRIC PANEL MOISTURE
Electric Power Frequency Table
ELECTRICAL BASICS
EMF RF FIELD & FREQUENCY DEFINITIONS
ELECTRICAL GROUND SYSTEM INSPECTION
ELECTRICAL SERVICE DROP
ELECTRICAL SERVICE ENTRY WIRING
ELECTRICAL TERMS
EMF RF FIELD & FREQUENCY DEFINITIONS

FIRE SAFETY Checklist, CPSC

GENERATORS, ELECTRICAL
GFCI PROTECTION,Testing GFCIs AFCIs

HEATING COST FUEL & BTU Cost Table
HEAT, ELECTRIC
HEAT TAPE USAGE GUIDE
Hertz - Definitions of KHz MHz GHz THz

KNOB & TUBE WIRING

LIGHTING, EXTERIOR GUIDE
LIGHTING, INTERIOR GUIDE
LIGHTNING PROTECTION SYSTEMS
LOW VOLTAGE BUILDING WIRING
LOW VOLTAGE TRANSFORMER TEST

MAIN DISCONNECT
MAIN DISCONNECT AMPACITY
MOISTURE SOURCES in PANELS
MULTI-WIRE CIRCUITS
MURRAY SIEMENS Recall

PHOTOVOLTAIC POWER SYSTEMS
PUSHMATIC - BULLDOG PANELS

REMOTE ELECTRIC POWER, PHOTOVOLTAIC
RUST in ELECTRICAL PANELS

SAFETY for ELECTRICAL INSPECTORS
SE CABLE SIZES vs AMPS
SIEMENS MURRAY Recall
SQUARE-D RECALLS

THERMAL EXPANSION of HOT WATER
THERMAL EXPANSION of MATERIALS

UNDERGROUND SERVICE LATERALS
VOLTS / AMPS MEASUREMENT EQUIP

WIND TURBINES & LIGHTNING

ZINSCO SYLVANIA ELECTRICAL PANELS

More Information

Water tracks on the service entry cable inside the electrical panel (C) Daniel Friedman 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
  • ELECTRIC PANEL INSPECTION - separate article - topic home
    • Electrical Panel Inspection Safety - separate article
    • Removing Electric Panel Covers - separate article
    • Electrical Panel Cover Screws - separate article
  • Questions & answers aboutvisible dangers & defects inside of the electrical panel
  • References

Click to Show or Hide Related Topics

  • ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR - home
  • AFCIs ARC FAULT CIRCUIT INTERRUPTERS
  • ALUMINUM WIRING HAZARDS & REPAIRS
  • AMPS MEASUREMENT METHODS
  • AMPS VOLTS DETERMINATION
  • BACKUP ELECTRICAL GENERATORS
  • CIRCUIT BREAKER SIZE for A/C or HEAT PUMP
  • CONDUIT, ELECTRICAL
  • CORROSION in ELECTRICAL PANELS
  • DEFINITIONS of ELECTRICAL TERMS
  • DIRECTORY OF ELECTRICIANS
  • DMM Digital Multimeter, HOW TO USE
  • DMM & VOM SAFETY
  • ELECTRIC HEAT
  • ELECTRIC METERS & METER BASES
  • ELECTRIC MOTOR DIAGNOSTIC GUIDE
  • ELECTRIC MOTOR OVERLOAD RESET
  • ELECTRIC PANEL AMPACITY
  • ELECTRIC PANEL INSPECTION
  • ELECTRICAL BASICS
  • Electrical Code Basics
  • ELECTRICAL OUTLET, HOW TO ADD & WIRE
  • ELECTRICAL SPLICES, how to make
  • ELECTRICAL TOOLS BASIC
  • ELECTRICAL WIRING COLOR CODES
  • ELECTRICAL WIRING BOOKS
  • ELECTRICAL DISTRIBUTION PANELS
  • EMF RF FIELD & FREQUENCY DEFINITIONS
  • FEDERAL PACIFIC FPE HAZARDS
  • GFCI PROTECTION,Testing GFCIs AFCIs
  • GROUND SYSTEM INSPECTION
  • GROUND SYSTEM REQUIREMENTS
  • KNOB & TUBE WIRING
  • LIGHTING, EXTERIOR GUIDE
  • LIGHTING, INTERIOR GUIDE
  • LIGHTNING PROTECTION SYSTEMS
  • LOW VOLTAGE BUILDING WIRING
  • LOW VOLTAGE TRANSFORMER TEST
  • MAIN DISCONNECT
  • MULTI-WIRE CIRCUITS
  • MURRAY SIEMENS Recall
  • OLD HOUSE ELECTRICAL WIRING
  • PHOTOVOLTAIC POWER SYSTEMS
  • PUSHMATIC - BULLDOG PANELS
  • SAFETY for ELECTRICAL INSPECTORS
  • SERVICE AMPACITY
  • SERVICE DROP
  • SERVICE ENTRY WIRING
  • SE CABLE SIZES vs AMPS
  • SIEMENS MURRAY Recall
  • SQUARE-D RECALLS
  • TEST EQUIPMENT, ELECTRICAL
  • THERMISTORS
  • VOLTAGE DETECTION & MEASUREMENT
  • UNDERGROUND SERVICE LATERALS
  • VOLTS / AMPS MEASUREMENT EQUIP
  • WIND ENERGY SYSTEMS
  • WIND TURBINES & LIGHTNING
  • ZINSCO SYLVANIA ELECTRICAL PANELS
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

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.

Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.

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 left) - this was the ground that overheated when there was no neutral connection in the sub panel and neutral and ground buses were improperly bonded.
Failed electrical neutral caused overheated ground and a shocked homeowner (C) Daniel FriedmanWater tracks on the service entry cable inside the electrical panel (C) Daniel Friedman
  • 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 net ural 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.
Improperly wired garage sub panel led to electrical shock (C) Daniel FriedmanNeutral wire was not connected in this sub panel but it looked as if it was (C) Daniel Friedman
  • 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.

FPE Stab Lok electric panel (C) Daniel Friedman

Opening the electrical panel to examine overcurrent devices - fuses or circuit breakers, is discussed at ELEC PANEL & GROUND

Inspecting overcurrent devices - visual: see ELECTRIC PANEL AMPACITY and ELECTRIC PANEL INSPECTION for detailed procedures. There is a huge amount of information about the electrical system inside of the electrical panels.

Reporting unsafe electrical panels: see FEDERAL PACIFIC FPE HAZARDS and see ZINSCO SYLVANIA ELECTRICAL PANELS

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).

General Electrical Safety Suggestions describes important basic safety procedures, clothing, and equipment for home inspectors and electrical inspectors.


Frequently Asked Questions (FAQs)

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Ask a Question or Search InspectApedia

Questions & answers or comments about shock and electrocution hazards when touching electrical equipment during an inspection.

Ask a Question or Enter Search Terms in the InspectApedia search box just below.

Technical Reviewers & References

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

  • 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: johncranor@verizon.net
  • Carson, Dunlop &
Associates Ltd., TorontoCarson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.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:
    • Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
    • Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
    • Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
      Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
    • The Home Reference Book, a reference & inspection report product for building owners & inspectors.
      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.
    • The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & 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.
    • 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.
    • The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
  • "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 mrelectricwa@gmail.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 protune@aol.com
  • 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

  • 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.
  • Home Reference Book - Carson DunlopThe 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.

  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
    Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd
  • Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
    Special Offer
    : Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.

  • 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)
  • ...

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