Posts Tagged ‘used circuit breakers’

Circuit Breaker Trip Device – Hidden Defect

February 2nd, 2011 Comments off
Square D PAL362000 Circuit Breakers For Sale

Square D PAL362000 Circuit Breakers For Sale

MIDWEST asked our Switchgear Engineering Technicians for an example of a molded case circuit breaker that had a hidden defect that could only be found by experienced testing.  We find many used circuit breakers that have defects that can be found by a close visual inspection.  Sometimes the defect may not be obvious but an experienced Engineering Technician knows where to look and would find the problem. In the business of repairing and reconditioning circuit breakers, we find about every possible problem that can occur. Whether we are reconditioning a replacement Westinghouse, General Electric or Siemens circuit breaker, many of the problems are the same. But we also frequently find hidden defects that could only be detected using proper testing.



For this example, let’s just use a replacement Square D PAL362000 circuit breaker. The breaker was reconditioned, which involved removing the cover to thoroughly inspect and maintain the interior of the Square D circuit breaker. The technician was immediately suspicious because he detected the slight smell of an overheated circuit breaker. Once you get that smell in your nose, you never forget it in the future. Even a small whiff tells you there may be a problem. In this case everything visible was in very good condition. There were no signs of overheating at the contacts or the line or load side breaker terminals. But the contact resistance test results indicated very high resistance on the center pole. A DLRO, digital low resistance ohmmeter, was used to locate the problem. The usual location is either the contacts, the bolted connections to the trip device, or the line or load side terminals or lugs. In this case the defect was inside the trip device. And a close sniff of the trip element confirmed it. MIDWEST performed an additional test, a high current test, to determine the voltage drop and therefore the resistance in the trip device on the center pole. Even though this replacement Square D circuit breaker looked just great, the trip device was defect and had to be replaced.

Scrap Circuit Breakers

December 23rd, 2010 Comments off


ED3100 Cutler Hammer Circuit Breaker

ED3100 Cutler Hammer Circuit Breaker

This morning I walked past three drums of old, obsolete, used circuit breakers. All these breakers were going to the scrap heap. Actually they go to a recycling company that crushes them and recycles the metal parts. If someone was to ask what we do with the defective circuit breakers, this would be the answer.  These drums contained Square D, Westinghouse, Cutler Hammer, Siemens, GE General Electric circuit breakers and probably many other manufacturers. If a circuit breaker is mechanically or electrically defective, if it doesn’t pass our inspection and testing quality control, it gets tossed into the scrap heap, actually drums. 

If you were to look at the breakers in the drums, you would find many that look in perfect condition, some even mint. But, if you tore them apart, you might find the contacts blasted beyond any possible repair. This is found with an internal inspection, contact resistance tests, or by a voltage drop test during over current testing.  One might be surprised how many old and even new surplus circuit breakers are rejected based on the visual inspection. And, again, you would be amazed at how many new looking circuit breakers fail one or more of the quality control tests.

No one manufacturer or model, whether Square D, Cutler Hammer or GE General Electric circuit breakers, is exempt just because of the name on the label. And no breaker can be evaluated just based on its appearance. Sometimes a circuit breaker may fail a test and we really have to look hard to find the cause of the defect. Sometimes the defect may not be visible, for example a defective over current trip device.


So you can’t judge the condition of an old or new surplus circuit breaker by its appearance. MIDWEST is always testing new circuit breakers as part of our Acceptance Testing Services on new switchgear, a common practice for hospitals, data processing centers, and mission critical facilities. And we do find deficiencies in brand new circuit breakers.  So again, appearances can be deceptive. 

100% Rated Square D 2000 Amp Circuit Breaker

December 15th, 2010 Comments off

MIDWEST lost a battle with the maintenance dollar.  A manufacturing plant had a 2000 amp Square D circuit breaker that was loaded to over 1800 amps, sometimes hitting 1900.  We detected the heavily loaded breaker during an Infrared Scan of the facility.  This was an old Square D circuit breaker mounted in a tap box feeding a 2000 amp bus duct. The local contractor recommended they just replace the breaker with a 100% rated breaker. He said they could use Square D, Cutler Hammer, or General Electric, whoever was cheapest and would fit. Because of the bus configuration, it only made sense to use the same Square D circuit breaker. The customer bit on the idea that just replacing the old circuit breaker would solve their problem and save them a lot of money. We strongly disagreed. Replacing the circuit breaker would make zero difference, in this case. The old Square D molded case circuit breaker was an 80% rated breaker.  More recent replacement Square D circuit breakers, same frame, model number, current rating, were 100% rated, ie 2000 amps. The 100% rated replacement circuit breaker was specified 100% if it was in an enclosure with a much larger volume than the old breaker. In other words, to achieve the 100% rating, the breaker must be in a much larger enclosure so as to properly dissipate the heat generated from 2000 amps. This all makes sense. But to just replace one breaker, whether GE General Electric, Cutler Hammer, Siemens, or Square D, with a 100% rated breaker and not address the installation requirements to achieve the higher rating can be a waste of dollars.  A quick check of the old and new circuit breaker specifications, will tell what the installation requirements are. This is the technical added value that is often ignored, or just not known, in too many facilities, as experienced personnel disappear.

            This facility decided to replace the circuit breaker, but later transferred load off the bus duct.

Aluminum Feeders Damage Old Circuit Breakers

July 2nd, 2010 Comments off

MIDWEST had a customer that seemed to call us about every 5 to 6 months for a replacement circuit breaker. This went on for about three years, before we noticed the pattern. We recognized it because he started calling the same Engineer.   We asked why he needed so many reconditioned replacement circuit breakers over the past two or three years. It seems their facility was built in the 1970s when copper was so scarce and expensive that many projects were built using aluminum cables.  Unfortunately some installations did not use the correct lugs or failed to install the lugs properly. We were very surprised they didn’t have these problems, or worse, decades ago.  We asked them if they still had a couple of the old damaged circuit breakers laying around.  Could they send us one or more of the old circuit breakers that had been damaged, so we could inspect them and give some recommendations on how to prevent future problems.  Inspection of two of their used circuit breakers that had failed, showed extensive heat and arcing damage at one or more of the load side lugs.  We have seen this type damage many times and it invariably was caused by cables that had become loose inside the lug or lugs that had become loose at the breaker connection.  One of our senior engineers worked in electrical construction during the years aluminum cables were used.  He explained how this could be dangerous and he also was very surprised they didn’t have problems many years ago.  He said a lot of new circuit breakers and MLO, ie main lugs only, panel boards were damaged when the aluminum cable terminations failed in the years after installation. He had one strong recommendation.  Hire an old time electrician who remembers those days and knows from experience what has to be done to correct things.  He said this can be a challenge. But, if they don’t do something, they may lose more than an occasional old circuit breaker. He also said to be extremely careful when installing a replacement circuit breaker. Always turn all the power off, including the feeder into the old power panel or panelboard. Safety first.

Expensive Small Replacement Circuit Breakers

May 28th, 2010 Comments off

How is it possible that a very small replacement circuit breaker, weighing only 2 pounds, would cost over $500 when a large replacement power circuit breaker weighing 200 pounds might be less than $1000?  MIDWEST frequently gets questions similar to this one.  The basic answer is economic supply and demand, the most fundamental law of a market driven economy.  A crude paraphrase would be “If the supply of a product goes down and the demand for the same product goes up, the cost of the product will increase.”  There are more people chasing fewer available goods, or circuit breakers.   In the world of supplying replacement circuit breakers, there are some small breakers that are no longer manufactured and are very rare, very difficult to find in the secondary market of used, reconditioned, and obsolete replacement circuit breakers.  For example, there are small molded case circuit breakers that you can hold between two fingers, but they cost over $500.  These breakers are no longer made. They are fairly common in some manufacturing facilities, but they are just not available. There are very few of them for sale and they are becoming scarce.  This is classic low supply and high demand.  On the other hand, there are large circuit breakers that are so common that they are not worth much more than scrap value.  A zillion of them were made.  Although they are no longer manufactured, they are a “dime a dozen,” so to speak. The supply is so large that it far exceeds the demand.  


The high cost of rare replacement breakers is supported by the fact that they are still far less expensive than replacing an entire power panel.  The high cost may seem unreasonable to someone purchasing an item for the first time. However, human nature would tend to look at the cost of a rare item as being too high, but not think of the cost of an abundant item as being too low.  

Top Ten Reasons to Buy Used Circuit Breakers

May 8th, 2010 Comments off

10.       If you haven’t discovered the great value of used circuit breakers you really should.


9.         The Karma given off from a used circuit breaker purchase pays rich dividends. You’ll have to experience it.


8.         Think of the future. Used breakers are of course green. The carbon credits you accumulate in this life do transfer to the next.


7.         Buying used circuit breakers saves time getting to work. Think of the time you’ll save walking from your car to your building with your new employee of the month parking spot. 


6.         Buying used breakers puts you in good stead with your significant other. No longer will you spend wakeful nights thinking about ways you can save your company money.


5.         Our used circuit breakers meet national testing standards.


4.         Our used circuit breakers are readily available. Manufacturers do not keep inventories of used breakers. Your breaker will be in your hands just as fast as preparation time allows. 


3.         Our used circuit breakers are fast and easy to purchase. Check out our web site at to see how easy it is.


2.         Only used circuit breakers can fit right in as a replacement for out of production panel board or cubicle configurations.


1.         And the number one reason to buy used circuit breakers is it saves money, up to 70% off the cost of new.

Obsolete Circuit Breakers

March 24th, 2010 Comments off

The word obsolete, when used in the context of circuit breakers, is not used in the pejorative sense but rather, in this case, obsolete simply means no longer produced.


Take a Square D QE3200VH molded case circuit breaker, considered an obsolete circuit breaker. This is a 3-phase 200 amp breaker with a very high current interrupting capability still used widely in industry today. It can be found in many types of metering stacks. The Square D EHB34100 is another in a family of obsolete circuit breakers still in wide use today. These two examples represent an enduring part of breaker history forming a strong and ongoing niche in the used breaker market.


Besides saving up to 70% of the cost of a new breaker when buying used, it may be the only good choice you have. Only the used electrical equipment market supplies replacement breakers for breakers in use but which are out of production. Panel board lineups are designed for specific types of breakers. It would not be feasible to replace a defective breaker in a lineup with a different type or style of breaker other than what the panelboard was originally designed to use.


Used circuit breakers should come with a warranty. In most cases you can expect a one year warranty on used circuit breakers, the same time offered by manufacturers of new breakers.  Always confirm the warranty.


Do obsolete circuit breakers meet the same national testing standards as new equipment? The answer is yes, if the used circuit breakers come from reputable suppliers that properly service and test the circuit breakers before shipment.