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Cutler Hammer electrical panel fire (C) D Friedman B KesslerCutler Hammer Electrical Panels
Inspections, Field Reports & Fires / Failures
CH panels, copper bus, crowded & split bus electrical panels

  • CUTLER HAMMER ELECTRICAL PANELS - CONTENTS: photographs of older Cutler Hammer electrical panel using a copper bus & comments on its condition. Separate field report of a Cutler Hammer Electrical Panel Fire, Photos, with speculation about possible causes. "The pool maintenance guy was there when he saw smoke coming from the panel and he shut off the main breaker."Speculation about possible causes of electrical panel fire - bad electric motor, panel age, corrosion. Possible CH circuit breaker or bus failure?
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Cutler Hammer electrical panel field inspection photographs, including a CH panel fire field report:

This article describes and includes photographs of a Cutler Hammer electrical panel fire that the electrician suspects was due to a faulty circuit breaker. This website provides information about a variety of electrical hazards in buildings, with articles focused on the inspection, detection, and reporting of electrical hazards and on proper electrical repair methods for unsafe electrical conditions.



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Cutler Hammer Copper Bus Electrical Panels

Article Contents

Cutler Hammer Spit Bus Electrical Panel

The following photographs, provided for identification, were taken by Bob Sisson, a Maryland home inspector and ASHI Member. Mr. Sissons reported these interesting observations:

Older Cutler Hammer electrical panel (C) InspectApedia.com Bob Sissons Older Cutler Hammer electrical panel (C) InspectApedia.com Bob Sissons

Ths electrical panel also had a GE sticker on the front, but it was a stick on label. The dead front and the Panel were Cuttler Hammer tan in color, and the deadfront was embossed Cuttler Hammer. Clearly this was an older, copper-bus Cutler Hammer split-bus electrical panel. Sisson adds that ... several people have recommended that I recommend replacement because of the split-bus and because of the panel age and likely cost of getting additional breakers. Another said he didn't like how the Main connected to the lower buss with the soldered wire... In any case it is "Obsolete".

Older Cutler Hammer electrical panel (C) InspectApedia.com Bob Sissons

Bob Sisson ACI, Inspections by Bob
ASHI Member # 212016
MD Home inspectors License #29666*
*MAC-ASHI Chapter President 2010-2012
ASHI Mid-Atlantic Group Leader 2009-2012
ASHI National Board Of Directors 2012-2015
Bob@Inspectionsbybob.com
www.inspectionsbybob.com
Email: bob@inspectionsbybob.com
(301) 208-8289

 

 

Hazards of Split Bus Electrical Panels & the Rule of 6 Circuit Breakers

Older Cutler Hammer electrical panel (C) InspectApedia.com Bob Sissons Older split bus electrical panel (C) Daniel Friedman

What about "split bus design electrical panels? A "split bus" electrical panel is one in which circuit breaker connections are configured so that a group of breakers in the upper panel include one or more that provides power to an electrical bus in the lower half of the electrical panel. In other words, there may not be a single "main breaker" that will turn off all electrical power.

Mr. Sisson's photo (shown at left) and our sketch (above right) illustrate split-bus designed electrical panels. Electrical power enters this panel at the top of the enclosure (in shadow, a heavy red and black wire).

Power on the upper bus supplies several circuits including the lower portion of the panel. See those heavy wires bringing power from the upper half of the panel down to the lower half? The electrical panel shown appears to have more than six breakers that must be thrown to turn off all power in the building as there are eight circuit breakers in the upper portion of this equipment.

Some inspectors dislike all "split-bus" design electrical panels in which multiple circuit breaker throws are required to turn off all electrical power in the building. But the "rule of 6" is what most apply.

Watch out: experts generally agree that if more than six circuit breakers must be thrown to turn off electrical power to the building the installation is not safe and may not comply with local or model electrical codes.

Where six or fewer breakers must be thrown to turn off all electrical power to the building the panel meets the safety "rule of thumb" or "rule of 6" but if you are inspecting such a panel be sure that all of the breakers that must be thrown to turn off building power are labelled as "MAINS"

Note: It is possible that the panel in Bob's photo is fed from a separate main breaker or switch. If so the "rule of six" does not pertain.

More examples of split bus electrical panels are shown and discussed at

Trouble with Crowded Electrical Panels

We can't see the rest of this electrical panel but from what we can see it may be fully populated. If the owners of this building want to add electrical circuits that will usually require either a sub panel and some massaging of wires in this older unit or more likely, the electrician will successfully point out that it'll be cheaper and safer and "better" to just install a new electrical panel with more circuit breaker positions and a single main shut-off.

Electrical Panel Failure Risk Assessment and "OPM"

Really? All professional inspectors with an ounce of sense or two drams of experience are nervous about telling anyone not to spend money on replacing old equipment where life-safety matters pertain. Even the most careful inspection and education cannot guarantee against all accidents.

But in discussion with a building owner or buyer client we should also consider the "OPM" problem: spending other people's money to reduce our own risk. That sort of risk reduction is almost free to the inspector but not to the client. Using scholarly research tools (30 April 2015) we did not find research identifying unusual failure rates for the Cutler Hammer electrical panel described above.

Urgent versus Desirable Electrical Panel Replacement

So how urgent is the replacement of this obsolete Cutler Hammer electrical panel? And do we agree with the advice given to the inspector by people who may include electricians who profit by the work?

We noted that this is a copper bus CH panel. Over time and compared with aluminum and plated aluminum bus designs, copper bus electrical panels perform better than average - at least for the extent to which copper buses don't have the same arcing issues as aluminum or plated aluminum bus panels. In our opinion this means that while the panel may be "obsolete" unless the electrician or inspector found evidence of damage such as overheating or modification or corrosion, a replacement decision may be handled as recommended but not an emergency.

If an electrical panel is visibly unsafe (damaged by rust, corrosion, mechanical damage, arcing, amateur modification, improper use or other detectable events) it should be replaced promptly. Separately we discuss a more urgent replacement of FPE electrical panels at FPE REPLACEMENT PANEL where replacement electrical panels made by Eaton Cutler Hammer are described.

Field Report: Cutler Hammer Electrical Panel Fire, Photos, Causation (?)

I have some more pictures from this CH meltdown

Cutler Hammer electrical panel fire (C) D Friedman B Kessler Cutler Hammer electrical panel fire (C) D Friedman B Kessler

Speculation about possible causes of electrical panel fire - bad electric motor, panel age, corrosion

My first objective was to install the new load center, the burnout started with the two pole 15 that feeds a 20 year old pool pump. I am going tomorrow to meet the inspector for the new load center and that is when I am going to look into the "why" this Cutler Hammer electrical panel burned.

But I suspect its from a fault at the swimming pool motor, and possibly because the age of the panel, corrosion, (only a couple miles from the ocean). But I'll know more tomorrow and let you know. The homeowner is elderly. The pool maintenance guy was there when he saw smoke coming from the panel and he shut off the main breaker.

Cutler Hammer electrical panel fire (C) D Friedman B Kessler Cutler Hammer electrical panel fire (C) D Friedman B Kessler

Suspected loose or defective circuit breaker cause of electrical panel fire

So after megging [checking the electric motor with a DMM or VOM - see ELECTRIC MOTOR DIAGNOSTIC GUIDE and DMM DIGITAL MULTIMETER HOW TO USE] the pool motor and the pool feeder I've determined it had to be a loose or defective breaker that started arcing out of control because the motor is fine and the feeders are fine.

Cutler Hammer electrical panel fire (C) D Friedman B Kessler



Like I mentioned earlier this home is only a couple miles from the ocean, the breaker had been installed for over 25 years. So I would guess that the breaker was loose or had loosened up. Also something I never liked about CA is this panel sat in the sun all day long, so maybe that had to do with it as well.

- Brian Kessler, Brooks Electric, 714-883-0894, Email: brian@brooks4electric.com

 

NOTE: while the views above are by an experienced, licensed electrician, this field report does not include analysis nor conclusions by a professional arson investigator.

 

Cutler Hammer Research & Research by Cutler Hammer Engineers

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