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This article discusses several inexpensive and useful test tools 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. Proceedings of the ASHI Home Inspector Educational Seminar: ASHI-NE Chapter Annual conference, September 22-23, 2008, Randolph, MA. -- Daniel Friedman.

Original text - Daniel Friedman, as ASHI Technical Journal Staff, January 1992,updates February 2006, September 2008. This is the full text version. A powerpoint presentation version of this class is also available. Readers of this article should also see these other building inspection safety articles:  Safety for Building Inspectors and  Septic Inspection Safety and also STAIRS, RAILINGS, LANDINGS, RAMPS - INSPECTIONS, CODES

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links 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.

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.

Guide to Using Electrical System Test Equipment to Check System Safety

These electrical inspection suggestions are not a complete inventory of all electrical components that should be inspected; nor have we described all of the electrical test tools popular among home inspectors and electrical inspectors. For example the SureTest® Circuit Analyzer model 61-164 and 61-165 made by the Ideal Corporation is quite popular among many home inspectors. (We'd welcome a contribution on the proper use of this tool.) Sometimes circuit analyzers are misused in testing aluminum wiring, FPE Stab-Lok equipment and AFCIs. Contact Us by email to suggest changes, corrections, and additions to this material.

First use your head:

Stop, look, listen before touching. More on "just looking" is provided when we discuss opening the electrical panel. Do not rely on touch to determine if electrical equipment is safe. Details about the hazards of touching electrical equipment and alternative advice for determining whether or not equipment is safe to inspect are provided at Touching Electrical Equipment.

Guide to Using a Tic Tracer™ to Test for Presence of Electrical Voltage

Guide to Using Non-Contact Voltage Sensing or Voltage Detection Tools

Guide to Using a Neon Tester to Test for Live Voltage or for Ground Paths

Tips for Using an Electrical Receptacle Tester to Check for Voltage & Proper Wiring Connections

Neither of these neat little electrical test tools can be relied on to report low levels of current leakage.

At an investigation of a garage roof that shocked a crew of builders during reconstruction after a lightning strike, we measured voltage varying between about 38 volts AC and 68 volts AC between some framing components and the earth. We could not detect these conditions with a neon tester. A VOM or DMM was needed.

Using a DMM or VOM to Check for Current

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.

Safe Use of Electrical Test Equipment: DMMs & VOMs

8.3 During an electrical system inspection the inspector is NOT required to
8.3.A. insert any tool, probe, or testing device inside the panels

Readers of this article should continue with a review of  Using DMMs & VOMs Safely .

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

Details about the hazards of touching electrical equipment and alternative advice for determining whether or not equipment is safe to inspect are provided at Touching Electrical Equipment.

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SAFETY: ELECTRICAL INSPECTION SAFETY
  Shock Risk Statistics
  Outside Electrical Inspection
  Electric Meter & Service Entry
  Local Electrical Grounding
  Electrical Panel Interior Inspection
  Removing Electric Panel Covers
  Electrical Panel Cover Screws
  Electrical Panel Interior Hazards
  Testing Main Breakers or Fuses
  Inspect Breakers, Fuses, Circuits
  Testing Receptacles GFCIs AFCIs
  When to Shut Down Equipment
  Touching Electrical Equipment
  Guide to Electrical Test Equipment
  Using DMMs & VOMs Safely
  Voltage Measurement & Detection
  General Electrical Safety Suggestions
  Electrical Inspection Client Safety

• Electrical shock injury statistics: www.healthatoz.com - September 2008;
• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• "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 mrelectricoly@msn.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 design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• ...

More Information on Building Diagnostic Inspections and Repairs

• * Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels
• Aluminum Wiring Information Website Aluminum 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.
• Ampacity of an Electrical Service: How to determine the electrical service size or ampacity entering a building
• 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.
• Lightning Strike Risk Assessment, Protection Systems & Services
• Multi-wire branch circuit inspection and defects
• 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.
• "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.
• Electrical System & Wiring Hazard Inspection, Detection, Cause, Remedy, Prevention - Main Electrical Page

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Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

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