GE Circuit breakers

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FrancisDoody

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Durham, CT
Has anyone else noticed that GE breakers will not trip as quickly as Square D or Siemans during a ground fault. The other day while installing a very large device in a 5 gang metal box (3 1/2 inch deep) a switch leg got jammed between a metal screw on the back of the device and the connection screw of the ganged box. After energizing the branch circuit and turning on the switch the switch leg strarted to burn, the #14 wire, till it was completely gone. The breaker never tripped.
 
GE breakers need to see about 40 times the handle rating to be in the instantaneous trip part of the trip curve. Square D and most other brands need 11 times or less. So with the GE breaker you are likely operating in the inverse time part of the trip curve and it will take longer to clear the fault. Some faults of this type, even though creating enough heat to melt the wire, do not pull enough current to cause the breaker to open.
Don
 
don_resqcapt19 said:
GE breakers need to see about 40 times the handle rating to be in the instantaneous trip part of the trip curve. Square D and most other brands need 11 times or less. So with the GE breaker you are likely operating in the inverse time part of the trip curve and it will take longer to clear the fault. Some faults of this type, even though creating enough heat to melt the wire, do not pull enough current to cause the breaker to open.
Don
Click to expand...

Wow - I just flashed back to 1964 and my EE101 class. The Prof had a long list of corollaries to Murphy's Law, one of which was:
A transistor protected by a fast-acting fuse will always protect the fuse by blowing first. It's good to know the wires will burn up fast enough to keep the breaker from tripping. I'd feel even better if I didn't know my own home has a GE panel.
 
whats the rating on a cutler-hamner! Thats what I have!

Now that you mention this, several places we have are bad about burning wires. They have GE breakers. And I've been blaming the operators! They reset and reset and......
 
Note that the trip point that I am talking about is the instantaneous trip point. As far as I know all of the other breakers have this trip point set at 11 times the breaker rating or less. After you get past the instantaneous trip point the inverse time part of the trips curves are close between all of the brands.
Don
 
I saw a mess of Homeline breakers in a GE panel the other day, and I thought about how "bad" that electrician was for not using GE or classified replacement breakers. Now, it might seem, he was doing a "good" thing (but probably for the wrong reason).
 
mdshunk said:
I saw a mess of Homeline breakers in a GE panel the other day, and I thought about how "bad" that electrician was for not using GE or classified replacement breakers. Now, it might seem, he was doing a "good" thing (but probably for the wrong reason).
Click to expand...

He was still doing the wrong thing because they are not rated for that panel.Personally i just never liked GE anything.Some of that attitude is from the days when i repaired TV's for a living.There idea of a 200 amp main breaker that is really 4- 100 amp breakers always seemed cheap to me and seen them fail.
 
I have always been intrigued by the reference to one breaker tripping faster than the another
But this is the way I address the issue:
Either a breaker trips instantaneously or it trips over time in response to an I2t curve.
If one refers to a fault, either arcing or bolted the breaker would trip instantaneously if and when, if ever, its magnetic calibration has been reached. That is there would be no time delay. If one could be assured that breakers of equal ratings from different manufacturers were subjected to identical faults, the one with the lower magnetic calibration would trip first of course. If it is an arcing fault the fault current may trip the lower calibrated breaker being that it is more sensitive and never rise high enough to trip the other.
Should there be a bolted fault that rate of rise of the current most likely will be instantaneous in all practicality where the trip times would not be an issue.
Also, if one were to review a trip curve it should be noted that there is a window for allowable calibration.
You will find that the common SqD QO mag calibration is between 6 and 11x the breaker rating and if subjected to a fault above that calibration will trip in 1/2 to 1 cyc. Ref. curve 730-1
The C-H BR breaker 7-40x also opening on less than a cycle at a current that exceeds the calibration, ref curve SC-4559-95.
The C-H CH breaker 7-30x, opening on less than a cycle at a current that exceeds the calibration, ref curve CH-4556.
I couldn't get on to the GE site as it was so slow it stopped loading which could be like their breaker trip response time, so I couldn't evaluate the GE breaker.
Considering that the QO is calibrated within a 6-11x window and the others in a 7-30 or 40x window the trip times could be the same if all were calibrated exactly the same in a 7-10x the breaker rating range which all have.
However the It is possible that the SqD could be calibrated below 7x, or down to 6x while the other may exceed the SqD's max of 11x or up to 30 to 40x.
What it may boil down to is the manufacturers concern over rejecting breaker with lower calibration than published. It would make more sense to shoot for calibrations in the higher range where there would be less of a risk of rejection and still be within their published trip curve values.
 
templdl,
The C-H BR breaker 7-40x also opening on less than a cycle at a current that exceeds the calibration, ref curve SC-4559-95.
Click to expand...
When I look at that trip curve it looks like it could take up to 6 cycles to open with a 40x fault. It looks to me like the maximum trip time line is vertical from the 40X current up to 0.1+ seconds. What am I missing? Then in the inset box, it says that for a 20a breaker the instantaneous trip is between 200 and 400 amps.
Don
 
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Jim W in Tampa said:
He was still doing the wrong thing because they are not rated for that panel.Personally i just never liked GE anything.Some of that attitude is from the days when i repaired TV's for a living.There idea of a 200 amp main breaker that is really 4- 100 amp breakers always seemed cheap to me and seen them fail.
Click to expand...

Back in the mid 80`s I made a killing changing out ITE quad mbr panels,seems they all failed at the same place.The connection to the buss bars.It was easy money and there were enough to keep me busy for awhile.
 
don_resqcapt19 said:
templdl,
When I look at that trip curve it looks like it could take up to 6 cycles to open with a 40x fault. It looks to me like the maximum trip time line is vertical from the 40X current up to 0.1+ seconds. What am I missing? Then in the inset box, it says that for a 20a breaker the instantaneous trip is between 200 and 400 amps.
Don
Click to expand...

This is a general curve, you need to apply all of the notes to correctly interpret the results. Notice at the .03sec and 200% point of the curve there is a note indicating the low magnetic curve of the 15-20A breakers.
 
Jim,
So looking at the low magnetic curve for the 15 and 20 amp breakers any fault ~18 times the handle rating or more should trip in one cycle or less, but a 10x fault could take as long as 90 cycles? Faults below 6x are in the inverse time part of the trip curve?
Don
 
Don,

I agree with those approximate numbers. They seem to confirm the information in the Inset table that says the 20A breaker top end is 400A.
 
Jim W in Tampa said:
There idea of a 200 amp main breaker that is really 4- 100 amp breakers always seemed cheap to me and seen them fail.
Click to expand...
According to an engineer I once asked, the 4-section main breakers actually incorporate a 2-pole 200a "master" breaker pair and a switch-only "slave" parallel pair that reduce contact resistance for improved current capacity. Only the inner two sections react directly to current.
 
I see what you are refering to Don and agree with you. I incorrectly stated the fact of when there is a call for a trip how long it take to clear the fault and not how long it takes the breaker to call for a trip as the TC illustrates.
The TC clearly illustrates what you are refering to.
 
Originally Posted by Jim W in TampaTheir idea of a 200 amp main breaker that is really 4- 100 amp breakers always seemed cheap to me and I've seen them fail.

LarryFine said:
According to an engineer I once asked, the 4-section main breakers actually incorporate a 2-pole 200a "master" breaker pair and a switch-only "slave" parallel pair that reduce contact resistance for improved current capacity. Only the inner two sections react directly to current.
Click to expand...
Something bothers me about that engineer's explanation.

If the "slave" parallel pair is actually going to reduce contact resistance, then there must be current going through those slaves.

If there is current going through the slaves, then it isn't going through the inner sections: "Only the inner two sections react directly to current."

Am I missing something here?
 
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