How many times can a breaker trip before it should be replaced?

[keepincool]

Does anyone have information on the best way to test a circuit breaker to see if it is bad? How many times can a breaker trip before it should be replaced? I'm sure the manufactures have a rated duty cycle for each breaker. Does anyone know where to find this information. I have tried several places and have only found the amount when used as a switch but not if it trips.

 

[drbond24]

I'm curious how this question came up. Do you have a breaker that has tripped so many times that you are afraid it is worn out? If so, perhaps you should be looking for the cause instead of worrying about the effect.

Other than that, why would the number of trip operations be different than the number of switch operations? In my opinion, they should be the same.

 

[charlie b]

. . . why would the number of trip operations be different than the number of switch operations? In my opinion, they should be the same.

I do not know the answer to the OP's question. But I do believe that the act of tripping on overcurrent imposes a harsher transient upon a breaker than the act of being manually opened.

 

[zog]

Does anyone have information on the best way to test a circuit breaker to see if it is bad?

Primary injection and compare to trip curves.

How many times can a breaker trip before it should be replaced? I'm sure the manufactures have a rated duty cycle for each breaker. Does anyone know where to find this information. I have tried several places and have only found the amount when used as a switch but not if it trips.

Depends on what type of breaker you are talking about, most are rated for around 2000 operations or 2-3 fault interuptions before they should be reconditioned. I have the specs for about every breaker out there. just tell me the type.

 

[jim dungar]

It really depends on your breaker construction and amp rating. Breakers built to NEMA and UL are different than those built to ANSI standards

Most molded case circuit breakers are rated for 1000's of mechanical operations and only 2 full rated fault interruptions. Overloads (even upto 10x) are faults that do not drastically shorten the life of the breaker. But without a fault analysis and identification of the fault, how do you know how much current the breaker actually interrupted.

 

[keepincool]

The question came up over a 50amp SquareD Homeline breaker, the A/C was causing the breaker to trip frequently and the homeowner indicated that he had reset the breaker numerous times. After recommending the replacement of the breaker the question was posed "How many times can it trip before it must be replaced?" I didn't have the specific answer, hence my question to the forum.

I am understanding from the previous post that most molded case breakers can be switched (mechanical operation) approx 1,000 times but can only trip (fault interruption) 2-3 times before replacement is recommended.

Thanks for the info.

 

[charlietuna]

From my experience i think it mainly depends on how high an overload a breaker is being tripped on. I have seen breakers trip one time on a direct short and never work again! Just a guess(and you know what they say about opinions), on a slowly applied overload--maybe twenty trips before the trip setpoint has a lower trip capability--again, thats my guess!

 

[Pierre C Belarge]

What really strikes me when reading this question is....
The load supplied from the breaker. AIR CONDITIONING. Most of us are freezing, and this guy is replacing AC circuit breakers.

 

[hardworkingstiff]

What really strikes me when reading this question is....
The load supplied from the breaker. AIR CONDITIONING. Most of us are freezing, and this guy is replacing AC circuit breakers.

GREAT observation Pierre! :smile:

 

[jim dungar]

...before the trip setpoint has a lower trip capability--again, thats my guess!

The trip point never varies with operations unless you have operated it enough times that the breaker latching mechanism is becoming worn out

On a small molded case circuit breaker like the 50A mentioned above, the criteria is: 6000 full load amp operations and 4000 zero amp operations for a total of 10,000 operations. So unless you have a very poorly manufactured breaker, that is well outside the UL operations parameters - most breakers will not wear out due to switching. Its overload performance is: 50 operations at 6x rated current (or 150A which ever is lower) so it is possible for a breaker to wear out electrically if it is subject to regular "instantaneous" tripping.

 

[Karl H]

Today, I saw a ITE single pole 20I bolt-on ( the one with the fin
that extends past the breaker where it bolts to the buss,BQ?) Breaker.
That the handle was in the "Trip" "Middle" postion. For some reason
or another I decided to check if it was open or closed. In the "Tripped"
postion, it was still closed. L-N.

I too have always wondered how many times a breaker can trip,before
needing to be replaced. I guess it depends on the type of breaker,
and the level of the fault.

 

[brian john]

In some cases once the second time can be dangerous, which is why you should ALWAYS TEST.

 

[Kdog76]

In some cases once the second time can be dangerous, which is why you should ALWAYS TEST.

To clarify, would that be testing for a dead short, as in a line to neutral fault or checking phase to phase for continuity? (which in either case would be bad).? Just want to see if that's what you would be checking for.

 

[brian john]

After a fault at a minimum the CB should be meggered with the CB open Line to Load, with the CB closed phase to phase, and additionally it would be recommended to micro-ohm/ductor the CB and I would high current test.

I would NEVER close a CB until the fault was located and the CB tested.

 

[Fulthrotl]

The question came up over a 50amp SquareD Homeline breaker, the A/C was causing the breaker to trip frequently and the homeowner indicated that he had reset the breaker numerous times. After recommending the replacement of the breaker the question was posed "How many times can it trip before it must be replaced?" I didn't have the specific answer, hence my question to the forum.

I am understanding from the previous post that most molded case breakers can be switched (mechanical operation) approx 1,000 times but can only trip (fault interruption) 2-3 times before replacement is recommended.

Thanks for the info.

my opinion, unmarred by any research or factual knowledge whatsoever,
is that with 10k interrupting capacity breakers of the type usually used
in home panels, when a breaker has been habitually overloaded and
repeatedly reset, it loses its spunkiness, and begins tripping at a lower
set point than the rating of the breaker. it starts feeling mechanically
unsound as well when you reset it, and sometimes won't reclose at all.

these are the symptoms of creeping breaker sickness. time to bury it,
and put another $5 breaker in.

for big breakers, rack in breakers, and such, go ask zog.

 

[zog]

After a fault at a minimum the CB should be meggered with the CB open Line to Load, with the CB closed phase to phase, and additionally it would be recommended to micro-ohm/ductor the CB and I would high current test.

I would NEVER close a CB until the fault was located and the CB tested.

To do otherwise is an OSHA violation.

10 CFR 1910.334(b)(2)"Reclosing circuits after protective device operation."

After a circuit is deenergized by a circuit protective device, the circuit protective device, the circuit may not be manually reenergized until it has been determined that the equipment and circuit can be safely energized. The repetitive manual reclosing of circuit breakers or reenergizing circuits through replaced fuses is prohibited.

 

[jim dungar]

my opinion, unmarred by any research or factual knowledge whatsoever,
is that with 10k interrupting capacity breakers of the type usually used
in home panels, when a breaker has been habitually overloaded and
repeatedly reset, it loses its spunkiness, and begins tripping at a lower
set point than the rating of the breaker. it starts feeling mechanically
unsound as well when you reset it, and sometimes won't reclose at all.

Factual knowledge causes problems?

The interrupting rating of a breaker has absolutely nothing to due with the life cycle (endurance) tests of a breaker.

Do some latching mechanisms in molded case breakers <=100A fail before they have reached their 6000 full load operations? Sure some do, it is all part of the law of averages.

 

[iwire]

As always we have people talking about 15 amp SP breakers at a home and some talking about large commercial / industrial breakers. Now there is nothing wrong with that except it makes the thread hard to follow and tough to know what the answer is. :smile:

To do otherwise is an OSHA violation.

(The above in reference to closing tripped breakers)

Take a look at the instructions on the panel of most any dwelling and it tells the homeowner to reset the breaker if it has tripped. No language to check or have the circuit checked and we know darn well HOs reset many breakers every day.

 

[brian john]

To do otherwise is an OSHA violation.

10 CFR 1910.334(b)(2)"Reclosing circuits after protective device operation."

After a circuit is deenergized by a circuit protective device, the circuit protective device, the circuit may not be manually reenergized until it has been determined that the equipment and circuit can be safely energized. The repetitive manual reclosing of circuit breakers or reenergizing circuits through replaced fuses is prohibited.

BUT so many electricians do not realize this, do not know this and NEVER consider a CB could fail, the one in the picture resulted in severe burns, damage to eyes, ego and loss of hair and the guy was out of work 6 weeks. In addition I have been involved in a case where the electrician closed a bolted pressure switch into a fault and did not live to tell about it.

 

[zog]

As always we have people talking about 15 amp SP breakers at a home and some talking about large commercial / industrial breakers. .

Well I was responding (more like adding to) Brians post that was talking about phase to ohase faults so I think that makes it clear what Brain and I are talking about. In all of my years I have never seen a phase to phase fault on a single pole breaker