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How to use Digital Multi Meters or DMMs Safely
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• Safety During Electrical System Inspections
• Using DMMs and VOMs Safely

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This article discusses How to use Digital Multi Meters or DMMs Safely - Safety Procedures for Inspecting Residential Electric Panels, volt meters, VOMs, electrical test equipment. This is a chapter of our electrical safety procedures article discusses safety hazards at residential electrical panels 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 are discussed.

Original text: DF, as ASHI Technical Journal Staff, January 1992, with updates February 2006. © 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.

Safe Use of Electrical Test Equipment: DMMs & VOMs

How to Test digital volt meter DMM or Volt Ohm Meter VOM meter condition

High energy measurement instruments: Use only DMM's (digital multi meters) or VOMs (volt-ohm meters, the analog predecessors to DMMs) designed for high energy measurements.

Frequently check for damage to the meter itself, or for loose, cut, or worn test leads. If you can see the conductor in the leads, replace them. Check that there is low resistance between the leads themselves - a partial indication of good condition.

Use well insulated test leads that have finger guards.

Don't use a meter having cracked or loose parts. In selecting a meter, look for recessed input jacks to reduce shock risks at the connectors.

Electrical Inspection techniques Using DMMs and VOMs

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

Do Not Grab an Shake SEC Entry Mains in the Panel

In his final electrical seminar in St. Louis a decade ago, Bob Smith, a lecturer from SHRC, the Small Homes Research Council, told ASHI home inspectors and candidates that he always verifies the quality of the service connection at the main breaker by grabbing the two hot entrance wires and giving them and the panel a good shake. Don't do this! Readers would not be warned here if this questionable advice had not been presented at that seminar. Electricians and trained experts work with live electrical wires. Home inspectors should not do so.

October 22, 1988 - El Cajon, CA - a young electrician died when he accidentally electrocuted himself. Acting police Lt. Carl Case said 19-year-old Sean M. Smith was working under a house, lying on his back working on an electrical addition to the house, when his wire [strippers] accidentally connected with a live wire. He said Smith's boss, Troy Beatty, heard the victim yell. Beatty found Smith unconscious under the house, pulled him out, performed CPR, and summoned help. -- IAEI News, November/December 1990 p.40.

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.

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

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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.

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
  General Electrical Safety Suggestions
  Electrical Inspection Client Safety

• Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
• 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]
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

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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