Procedures for inspecting the fuse panel or electrical panel:
This article discusses safety hazards during inspection of the electrical panel at residential properties and suggests safety procedures for the electrical inspector, home inspector, or other professionals who examine residential electrical systems.
We review several standards for electrical system inspections - at the electrical panel. How to use test equipment at the electrical panel during electrical. inspections in order to improve safety.
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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.
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Homeowner advice for electrical panel safety: These safety suggestions are for professional inspectors and are not a guide for homeowners. Homeowners should not remove the cover from an electrical panel - it is unsafe to do so.
Homeowners should look at their electrical equipment for signs of trouble and should contact a licensed electrician to address any concerns that arise.
Without removing the electrical panel cover, but by opening the hinged electrical panel access door, homeowners can access the main circuit breaker or fuse, as well as individual circuit breakers and fuses. These devices may be turned on or off by the homeowner as safety or other needs require.
8.3.C. [The inspector is NOT required to] dismantle any electrical device or control other than to remove the covers of the main and auxiliary distribution panels.
At least three deaths have been reported to have occurred during the inspection of an electrical panel.
Atlanta GA, a licensed electrician was opening the panel for inspection.] Apparently there was an incipient problem with the spring-loaded bus-bar assembly. When the cover was removed the bus assembly moved, an arc caused an electrical explosion, killing the inspector. -- J. Aronstein to D. Friedman, personal communication, 12/1991.
The Assistant [Fire] Chief accompanied a contract electrician, the Assistant Building Engineer, and the Loss Control Manager to the engineering room on the first floor which houses electrical panels for the store.
During testing of one of the panels, a fault occurred, resulting in the formation of a fireball, killing the Assistant Chief and the electrician. The Assistant Building Engineer received serious burns. - NFPA - 06/11/1999
The following photos and text provide examples of external evidence that may let the inspector avoid trouble or a nasty surprise when inspecting electrical equipment.
This photo shows a common way that water may enter an electrical panel as well as drip on its exterior.
A cold water pipe produces condensation which drips on the panel top. This pipe is too close and is in a poor location over this electrical service box.
Is there:
The pair of photographs below show two clear warnings that water has been entering an electrical panel - watch out for rust, and for circuit breakers that may not trip in response to an overcurrent, due to internal corrosion.
This defect is not one for which a home inspector (nor most electricians) can reliably test in a home, but the warning remains appropriate. Replace such breakers, and if the electrical panel is badly corroded the entire panel needs replacement.
See RUST in ELECTRICAL PANELS for a detailed account of the sources of water and rust in electrical panels and the frequency of observation of rust and water damage in that equipment.
ASHI Standards 8.1.B [The inspector shall observe] service equipment, grounding equipment, main overcurrent device, main and distribution panels.
Details are at ELECTRICAL PANEL COVER REMOVAL
The author asks clients to stand a little back while removing the cover, which makes it easier to remain in a blocking position (below).
We might inform the client that opening the panel is a dangerous step, and that if sparks fly the client should not touch the inspector - though other parties present at the inspection might want to kick the inspector or take similar measures if necessary.
At an inspection in a damp dark crowded basement the author was standing blocking the very curious and active participatory client from the open electrical panel after the cover had been removed.
The client reached over the author's shoulder.
The client asked, "What's this?" as he stuck his finger straight into an open fuse socket while his arm contacted the inspector's shoulder, assuring that they both would get an electrical shock.
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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