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Electrical Main Fuse/Breaker Inspection:
Should you ever pull the main fuse or switch off the main circuit breaker in the electrical panel?
Special hazards are faced when pulling a main fuse block even though this is a device intended for emergency use by a homeowner. Special hazards are faced when switching on or off a main circuit breaker.
This article discusses safety hazards at residential electrical panels when the main fuse is pulled or main breaker is switched. While we recommend that a professional inspector check these devices in some circumstances s/he should not do so, and extra care is always needed.
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
Testing Main Circuit Breakers or Main Fuses in Electrical Panels
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.
Photo: with cover removed on this main electrical panel in Buenos Aires you can see that it would be too easy to accidentally touch a live electrical terminal or wire. [Click to enlarge any image]
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.
8.1.D. [The inspector shall observe] branch circuit conductors, their overcurrent devices, and the compatibility of their ampacities and voltages
In addition to examining the electrical panel before touching it, looking for dangerous conditions like water, rust, sheet metal screws, rats, and blocking client access, the inspector should also recognize that certain brands or models of electrical equipment are known to be unsafe and may be dangerous to inspect or operate.
Federal Pacific Electric Stab-Lok equipment includes breakers which remain internally "on" when switched "off", as well as too often failing to trip off in response to an overcurrent, and which have been reported to result in electrical arc explosions when manually or otherwise exercised.
Circuit breaker photo: in a GE-branded FPE circuit breakers panel (unsafe) you see rust and you see that the breaker is recessed in the panel - either the cover is loose or the breaker and / or cover are not properly mounted.
Contact Us by email to add field reports of problems regarding these or other electrical products.
8.3.B. [The inspector is NOT required to] test or operate any overcurrent device except Ground Fault Circuit Interrupters
I continued to put my arm behind my back and close the breaker with my left hand with my head turned to the left.
BAM, a light as bright as the sun and an explosion.
This knocked us down and blinded us.
We were rushed to the hospital. I spent the night in the ER with an ICU nurse and was off of work for 3 weeks and have had to have a stronger prescription.
These FPE panels are all over the building
Pulling fuse blocks: At one inspection the author pulled the main fuse block in a 60-Amp
panel, only to have the pullout block disintegrate in his hand.
failure left one fuse in place and one half out of the panel.
did you just do to the panel?" asked the client (from a safe distance).
"I destroyed it." was the answer.
With permission of the owner, and following accepted home inspection practice of exercising normal user controls intended for use by the homeowner, the home inspector was performing
a normal, if uncommon operation which a homeowner would be expected to do, for example, during an emergency or other need to shut off
electrical power to the building.
At a minimum one would have had to
perform this operation during an emergency or if the panel were to
be worked on.
The client wanted to know if the fuse pullout disintegration was normal. [No.]
The inspector wanted to know if he was going to pay for a new panel. [No.]
A new panel was needed as the service and equipment were obsolete, not because
the fuse pullout needed replacement. But we pose that it may be difficult to find a replacement fuse pull-out for some older fuse panels.
If you had not pulled the fuse shown at lower right in this photo, something interesting would have been missed.
Is that smaller fuse unsafe? No, installing a smaller fuse means that the overcurrent device will open the circuit under less current flow.
What about the other wiring in the panel? There is an unsafe open splice at the right side of the panel.
Are some of the edison-base fuses oversized? Can't tell for sure from the photo. In older fuse panels people are too often tempted to get around a frequent problem with blown fuses by installing an over-sized fuse - this is an unsafe action and is a fire hazard. Be sure that fuses in the panel are matched properly to the wire size.
#14 copper wire wants a 15-Amp fuse.
#12 copper wire circuits can be fused with at 20-Amp fuse.
Are Old Fuse Panels Safe?
Shown here is an antique fuse panel that was produced by the Columbia Metal Box Company and marketed under the brand Safe-T-Cirkits.
This is a 62-Amp rated fuse panel carrying ten fuses, providing power to ten electrical circuits in an older Poughkeepsie New York home.
A complete safety assessment of this electrical panel would require further inspection of the panel interior, the condition of its fuses, wiring, and connections as well as a check for signs of over-fusing or overheating.
But here are some initial antique fuse panel safety observations we can make from even a cursory inspection.
Fuses are reliable:
In my OPINION, one shared at least some older electricians, fuses are inherently safe, perhaps safer than more-modern circuit breakers as the fuse is less likely to fail to "blow" to turn off an electrical circuit in unsafe conditions.
The fusible strip inside the fuse melts at over-current giving a reliable switch-off of power to the circuit.
In a damp or corrosive environment fuses may be more-reliable than a typical residential circuit breaker that may jam due to corrosion.
No Main Switch:
the ten circuit fuse panel shown has no main fuse nor main switch. Modern electrical safety practice recommends the provision of a local main switch for any electrical panel having more than six circuits.
Over-fusing is unsafe:
Over-fusing is a common safety hazard we find in buildings where there are too-few electrical circuits and/or circuits are regularly over-loaded.
To stop fuses from blowing and turning off the circuit the occupants simply screw-in a larger-ampacity fuse. We are probably seeing this in the photo above where two 20A fuses have been inserted on what is probably a #14 wire - a 15-Amp electrical circuit.
The fuse size or ampacity must be proper for the wiring size and ampacity. It is safer to install a lower ampacity fuse if you're not sure about the circuit wire size or condition. It is never safe to install a higher-ampacity-rated fuse than the circuit intends.
a blown fuse has to be replaced while a circuit breaker can be simply switched back-on.
Research on Old Fuse Panel or Circuit Breaker Panel Safety
History of the Columbia Metal Box Company, 260 East 143rd St., New York, NY. Notice that our image of a Cloumbia Qualith electric safety switch data tag sows a different address: 226 East 144th St., New York, NY.
The Columbia Metal Box company made a variety of steel cabinets including bathroom cabinets, electrical enclosures, mail boxes, panel boards, conduit fittings, even steel radiator enclosures. The company operated at least in the 1930's - 1950's in New York.
Electricity is a safe and convenient source of energy for heat, light and power in your home and on your farm, provided it is distributed in correctly sized and properly protected conductors. Good wiring systems are safe and energy-efficient.
Many older homes and service buildings are not adequately wired to serve today's electrical loads. Some new homes fall into this category, too. The
safety of the system depends first on how well you have maintained the safety valves — your electrical fuses or your circuit breakers.
depends upon the care taken by the home builder or electrician in the placement of electric cables.
All cables in attics should be placed on top of
attic insulation materials. It is especially important that circuit conductors that carry near-capacity current are on top of attic insulation so that heat
generated within cable jackets will not be trapped.
Where a circuit carries near-full load (90 to 100 percent of rated capacity) for long periods of
time and heat is trapped by attic insulation, the conductor insulation could deteriorate..
Abstract excerpt: Aging residential wiring is a major issue as the number of housing units over age 40 increases, historic
preservation and restoration increases, and old wiring falls further behind with regard to improvements in the
National Electric Code.
Corroded wiring and arcing at poor connections behind faceplates of outlets and
switches and in light fixtures are a few of the causes of 40,000 fires annually from poor wiring, often in older
This annually results in 350 fatalities, 1,400 personal injuries, and upwards of $1 billion of property
losses, not to mention inconveniences and frustrations (Larder, p. 1, 2004).
The U.S. Consumer Product Safety
Commission continues to study these issues and to report statistics regarding this growing issue.
Electrical shock injury statistics: www.healthatoz.com - September 2008;
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 email@example.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 firstname.lastname@example.org
Rex Cauldwell, master electrician and contributor to the Journal of Light ConstructionOn 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
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)
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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