Hazards of touching electrical equipment - safety procedures: this article reviews safe and unsafe methods for touching or not-touching electrical equipment during its inspection. Warning: photographs in the article below include one of a gruesome death by electrocution. Electrical safety is an important consideration for both workers and building owners/occupants, and the hazards are real.
This is a chapter of our article on electrical safety procedures which 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.
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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. Original text: DF, as ASHI Technical Journal Staff, January 1992, with updates February 2006.
Watch out: See SAFETY for ELECTRICAL INSPECTORS. 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.
During an inspection an ASHI inspector warned the home owner that there was a short in a florescent ceiling light fixture.
The owner, a contractor who had done his own electrical work, irritated and incredulous at this supposed defect, licked his knuckles and bridged a small space between the light body and a nearby gas pipe. He's now a believer. [NOTE: DJF home inspection, Beacon, NY 1990]
A very questionable procedure is suggested in The ASHI Training Manual [NOTE: "Electrical Systems," ASHI Training Manual, chapter by Alfred L. Alk, p. 18. ASHI 1987] indicating that the inspector can "test" to see if a panel is dangerously "live" (has an internal short) by tapping the box with the knuckles of his/her right hand to check for current, then laying the right palm on the box to feel for heat before beginning to remove the cover.
From a safety view, this is a bad idea. Never rely on physical touch to judge electrical safety of a component. Use instruments.
Test instruments such as the VOM described above, and the TIFTM Tic Tracer shown at left are inexpensive, effective, safer when used properly.
NOTE: Alexandra Radkewycz, a Canadian researcher, reports severely shocking experiences from failure to make proper use of instruments. [Private communication to author, 12/91.]
We describe the TIF Tic Tracer in detail, including providing examples of its use,
The gruesome death by electrocution shown in the photograph at page top occurred when the man shown tried to steal electrical power from a high voltage cable. - Jim Simmons
Shocked homeowner: During an inspection an ASHI inspector warned the home owner that there was a short in a florescent ceiling light fixture. The owner, a contractor who had done his own electrical work, irritated and incredulous at this supposed defect, licked his knuckles and bridged a small space between the light body and a nearby gas pipe. He's now a believer. [NOTE: DJF home inspection, Beacon, NY 1990]
Amazing Albert Alk: A very questionable procedure is suggested in The ASHI Training Manual [ "Electrical Systems," ASHI Training Manual, chapter by Alfred L. Alk, p. 18. ASHI 1987] indicating that the inspector can "test" to see if a panel is dangerously "live" (has an internal short) by tapping the box with the knuckles of his/her right hand to check for current, then laying the right palm on the box to feel for heat before beginning to remove the cover.
Watch out: DO NOT RELY ON THESE UNSAFE METHODS.
Babbling Bob Smith: an electrician asked to lecture to home inspectors at a conference we organized advised that home inspectors should check the security of the incoming mains connections at the electrical panel by grabbing the wires and giving them a good shake and pull. His advice was so mistaken that we were forced to interrupt the lecture to exclaim and issue a warning.
Watch out: DO NOT DO THIS. While an experienced electrician, wearing proper safety equipment, will in some circumstances have to touch or hold live electrical wires, there is risk of death by electrocution. This wire grabbing and shaking is not something that a home inspector or home owner should ever attempt.
From a safety view, these are bad ideas that can kill someone. Never rely on physical touch to judge electrical safety of a component.
Use electrical test instruments to check for live voltage. Test instruments such as the VOM described above, and the TIFTM Tic Tracer (above), and the contact and "touchless" pens (photo at left) and tools used to detect the presence of voltage are inexpensive, effective, safer when used properly.
[Alexandra Radkewycz, a Canadian researcher, reports severely shocking experiences from failure to make proper use of instruments. Private communication to author, 12/91.]
See VOLTS / AMPS MEASUREMENT EQUIP for a description of tools used to detect the presence of live electrical wires & devices and for the measurement of actual volts or amps.
See DMMs VOMs SAFE USE OF for details about using test equipment during an electrical inspection.
In the same ASHI Training Manual chapter the author, Al Alk, offers another more accepted suggestion: "Inspectors should practice working around open enclosures with the left hand behind the back.
If the right hand receives a shock the current will more likely pass down the right half of the body: the heart is on the left side. Inspectors who wear rings must be especially wary when working near an open box." [NOTE: ASHI Training Manual, Op. Cit.- Obsolete]
Grounding: A basic rule for working around electrical equipment: if you are yourself not grounded, and if you only touch one single component at a time, risks are reduced. Never ground yourself through your feet. Don't stand on a wet floor. If it's necessary to touch electrical components in such a location, a trained electrical worker uses a dry ungrounded platform such as boards or a wooden ladder.
Rings and watches: When working around electrical equipment, first remove rings and watches to reduce the risk of electric shock. At an IBM test site in Poughkeepsie, NY in the 1980's a test technician was killed while working on a computer. His metal watch band contacted a live component while other body parts were touching a grounded component, possibly the steel frame of the assembly. Similar accidents around electric panels are a real risk for home inspectors.
Electric Panel cover screws: if you find that a sharp-tipped sheet metal screw has been used (usually to replace a lost original fastener) you should be alert for pierced, damaged, short-circuited wires in the panel - both during removal and during panel cover replacement. We will not reinstall a sharp-pointed screw in a panel cover if wires are crowded close to the screw opening. Having seen more than one shorted and burned panel from precisely this cause, we warn clients about this unsafe detail. It is trivial to correct.
The most basic electrical safety procedure I can think of when working on electrical devices or electrical wiring involves knowing how to:
I never touch something electrical that I've "turned off" without using at least a neon tester to or a voltage detection pen to see that electrical power is really off. In 1970 I turned off power to a junction box to fix a light - the light went out - so I figured that all electrical power to the junction box was really off. Then while wiggling wires in the junction box I got a huge spark and a little shock.
Some nitwit had run two different live circuits into the same junction box.
Now I'm more careful. I figure that if you don't electrocute yourself, the rest is easy - you can always run out of a burning building. Well really inspectors have more responsibility than that: in addition to not killing yourself, you must protect the safety of your clients and of the occupants of buildings on which you've performed work.
VOLTAGE MEASUREMENT EQUIPMENT describes voltage sensors, DMMs, VOMs, and other choices of equipment we use for testing electrical circuits and for performing basic electrical or appliance wiring repairs.
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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