Non Tripped Circuit Breaker

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wireddd

Member
Got a phone call today from a good customer of mine informing me that a GE under the counter ice maker caught on fire over the weekend. This is in a bar area of this residence for retired priests. The unit plugs into a standard 20 amp 120 volt outlet. Unfortunately the circuit breaker did not trip. They want to know why the wiring inside the unit could burn up without tripping the breaker.
Any thoughts would be appreciated. These are Cutler Hammer single pole 20 amp type BA breakers. Many times we here of recalls about toasters or dishwashers with similar problems
 
ultramegabob

ultramegabob

Senior Member
Location
Indiana
no direct fault to ground, and the internal componants overheated but didnt draw enough current to cause breaker to trip. (could be caused by loose connections)
 
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wireddd

Member
They had a GE repair service come out and the "TECH" said it was too far gone.
Also wanted to know why the breaker didn't trip. The next step is he's going to send out someone from GE to investigate. Could be the start of a whole new recall.
 
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templdl

Senior Member
Location
Wisconsin
The breaker is a dumb device as it can't smell smoke or see a fire.
all it can resond to is the thermal I2t overcurrent curve and the magnetic or instantaneous pick up for a short circuit. The magnetic calibration may be as little as 6x the rating of the breaker or much greater than 10x.
If the current which is flowing through the breaker is not great enough to cause the breaker to trip fir or no fire, smoke or no smoke, the breaker has no reason to trip.
This is very common with arcing faults which often do not draw enough foult current to trip the breaker magnetically of enough over current long enough to trip the breaker thermally.
 
2

220/221

Senior Member
Location
AZ
They want to know why the wiring inside the unit could burn up without tripping the breaker.
Click to expand...

A toaster gets red hot without tripping a breaker.


Loose connections = high resistance = heating elements.
 
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mpoulton

Senior Member
Location
Phoenix, AZ, USA
ohm said:
good comeback!

More fuel for the AFCI proponents though.
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A toaster gets red hot without tripping an AFCI, either. Resistance "faults" cannot be sensed by any means, because they function exactly like a normal load. No way around this.
 
brian john

brian john

Senior Member
Location
Leesburg, VA
mpoulton said:
A toaster gets red hot without tripping an AFCI, either. Resistance "faults" cannot be sensed by any means, because they function exactly like a normal load. No way around this.
Click to expand...


Sure they can if the OCP is sized much lower than current standards, or individual equipment OCP.
 
charlie

charlie

Senior Member
Location
Indianapolis
mpoulton said:
. . . No way around this.
Click to expand...
If the AFCIs work as advertised, they will indeed protect against this type of fault. This can not be a straight line resistance fault, it will propagate to an arcing fault somewhere along the line. :smile:
 
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mpoulton

Senior Member
Location
Phoenix, AZ, USA
brian john said:
Sure they can if the OCP is sized much lower than current standards, or individual equipment OCP.
Click to expand...

A resistance fault, in this case, refers to a situation where a connection has become corroded or loose, resulting in an increase in resistance in the circuit and causing dissipation of heat in a location where no heat should be produced. This reduces the current draw in the circuit, not increases it. No OCPD can address this problem.
 
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mpoulton

Senior Member
Location
Phoenix, AZ, USA
charlie said:
If the AFCIs work as advertised, they will indeed protect against this type of fault. This can not be a straight line resistance fault, it will propagate to an arcing fault somewhere along the line. :smile:
Click to expand...

That's the catch - it only works once the fault progresses to an arcing condition. As long as it's merely a high resistance connection, the AFCI will not trip (nor is it supposed to). I'm not convinced that these things will reliably progress to an arcing condition BEFORE setting the building on fire - there's no reason to believe that. High resistance connections can cause plenty of heat to start a fire without ever becoming loose enough to arc.

My general opinion is that AFCIs address a subclass of faults that are not common enough to warrant their use - or at least it hasn't been proven that they do. This is not at all like GFCIs, which clearly solve the most common causes of electrocution. Anyways, I'm ranting.
 
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ohm

Senior Member
Location
Birmingham, AL
charlie said:
If the AFCIs work as advertised, they will indeed protect against this type of fault. This can not be a straight line resistance fault, it will propagate to an arcing fault somewhere along the line. :smile:
Click to expand...

I have to agree with the fish man. And one thing the layman can do is turn on an ordinary AM radio, tune it off any stations and listen for a tremendous increase in static, if they suspect an arcing problem.

Move the radio close to a dimmer to see what I mean.

An increase in broadband noise is one of the components AFCI's use to identify the arc.
 
charlie

charlie

Senior Member
Location
Indianapolis
mpoulton said:
. . . As long as it's merely a high resistance connection . . . My general opinion is that AFCIs address a subclass of faults that are not common enough to warrant their use . . . This is not at all like GFCIs, which clearly solve the most common causes of electrocution. . .
Click to expand...
I do not believe you can have a high resistance arc without introducing a arc signature that the AFCI will see and open the circuit. I agree with your second and third statements. :)
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Charlie,
The high resistance connection does not have to be an arcing connection. It is just a high resistance point in the system that will create excessive heat. An AFCI will not detect this until the fault progresses to an arcing fault or a ground fault. The progression happens when the heat causes enough damage to the insulation to result in a arcing fault or ground fault. The AFCI people went to great lengths to say that a series arcing fault cannot exist on a 120 volt system in some of their comments in the ROPs and ROCs. That was when the original AFCIs only looked at parallel arcing faults and ground faults. Now that they say they have a device that also looks at series arcing faults, they have changed their mind about the existence of 120 volt series arcing faults:confused:
 
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