Electrical Safety Hazards and Safe Electrical Inspection Procedures for Electrical Inspectors & Home Inspectors InspectAPedia® -
Safety procedures during inspection of the electrical grounding system
Standards for Electrical System Inspections
How to use test equipment during electrical inspections
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This article discusses safety suggestions when inspecting the grounding system at residential electrical systems and suggests safety procedures for the electrical inspector, home inspector, or other professionals who examine residential electrical systems.
Safe electrical inspection procedures and safe use of
volt meters, DMMs, multimeters, and similar electrical test equipment
is discussed at the end of the article.
Readers of this article should also see GROUND SYSTEM INSPECTION - on how to inspect the electrical grounding system and what common defects may be present.
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.
Inspect the Local Electrical Grounding Electrode or Grounding Connections
Do not assume that the grounding electrode is a real one. Kick it. We find short scraps driven into the ground that can sometimes just be pushed over or pulled out, as our client is demonstrating. Often ground connections have come loose, were never connected, or have corroded away. The ground connection shown here is not reliable. The inspector has easily lifted the short ground rod out of the ground. (Photo above left)
Do not assume that the utility company's ground (back at the pole) is connected and working. Sometimes that ground has been lost and only the local ground is present - a very dangerous condition. See Case History: Double Fault Leads to Loss of Power for an account of loss of both local ground and utility company ground at a property.
Do not assume that water pipes form a good ground - original metal pipes extending into the soil may have been replaced with plastic. (Photo above right)
Do not assume that grounding connections you see are actually secure and making good electrical contact.
Using a Neon Tester, a DMM or VOM to Check Grounding Connections
A simple volt ohm meter volt-ohm meter (VOM) such as the TriplettTM 310
or our little mini digital multimeter (DMM) shown at left can be used to test for unexpected and unsafe voltage at a component.
Testing for live voltage: this procedure describes a method for checking for the presence of live voltage.
During electrical work when we want to know if a metal part is connected to the grounded conductor (neutral) or to ground, we might use a neon tester to create a connection between a point of live voltage and the item which is being tested for grounding.
Be careful: this is not a reliable nor a complete test. For example, a weakly-grounded wire or electrode may look just fine when tested with a VOM, a DMM, or a neon tester, but when subject to higher current flow the ground may be completely inadequate.
Never touch metal plumbing or gas system pipes while you're working
around electricity.
Never touch electrical equipment while standing
on a damp or wet surface. [Unless you are trained and are wearing appropriate protective gear.]
For example, if the meter indicates more than 1or 2 volts between a service panel cover and ground, there's a safety problem. Most low-cost
analog-type meters such as the one described provide additional ranges
used to read lower voltages with more sensitivity.
Some VOM models provide alligator clips for the ends of the test probes. These clips permit measuring high voltage without handling
the probes. Always shut off the power before connecting the alligator
clips.
General Electrical Safety Suggestions describes important basic safety procedures, clothing, and equipment for home inspectors and electrical inspectors.
These electrical inspection suggestions are not a complete inventory 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
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Handling Immediate Threats to Life and Safety at a Building Inspection
If in the inspector's judgment equipment is an immediate threat to life and property, such as a boiler whose flue connection has fallen off, we recommend that dangerous equipment be shut down and the appropriate people notified. See Shutting Down Unsafe Equipment. In some cases "appropriate people" includes not only the client and building owner, but also building occupants.
In some instances such as sparking electrical panels, gas leaks, or evidence of a fire, the inspector and everyone else should leave the building immediately and from outside, call the fire department and as appropriate, the gas company, police, or rescue personnel.
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Electrical shock injury statistics: www.healthatoz.com - September 2008;
"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]
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.
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)
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.
Circuit Breaker, a bad one fails to trip failure at aluminum bus-to-circuit breaker connection - field report and photographs
Electrical Panels, How to Inspect in Buildings, safety for electrical inspectors, electrical panel, fusing, wiring defects, defective products. Inspection Class Presentation
Federal Pacific Electric (FPE) Stab-Lok Circuit Breaker Panel Hazards Website - Latent fire hazards, in-depth authoritative research, documents, advice on Stab-Lok electric panel and circuit breaker failures and what to do when this equipment is found in buildings.
"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.
"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.
More Information on Building Diagnostic Inspections and Repairs
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