Circuit Breakers Blog – Expert Safety and Usage Information

A free 3000 amp circuit breaker! This sounded too good to be true when MIDWEST’s Switchgear Shop made the announcement.  And, of course, they were just being wise guys. It was another opportunity to spin up the Engineers a little, and it worked. What they meant was the breaker was shipped loose on the pallet, in other words free. It seems MIDWEST was shipped an old 3000 amp power circuit breaker for maintenance and testing.  The breaker was properly wrapped, boxed, and strapped to a sturdy piece of plywood.  The plywood was on a sturdy pallet. Looked like someone did a good job shipping this fairly large power circuit breaker. 

But, the breaker was free, loose on the pallet, because the plywood was not fastened to the pallet. It could just slid around, slid right off the pallet. We’ve seen a lot of different techniques used to ship old and new circuit breakers. Some good ideas and some bad. In this case, someone went all out, but still missed the mark.  Fortunately there was no damage and we added this information to our training file.

An all too frequent scenario experienced by customers working in power distribution involves an air circuit breaker which after having tripped open fails to close again. When racked-in and the breaker charged it may trip free when the close button is engaged. 

Running down the list of possible factors, there are several key culprits which come to mind. Topping the list is the breaker racking-in interlock mechanism.  This interlock system is designed to ensure the breaker is fully in the racked-in position, the contact fingers fully engaged with the bus contact stabs, before closing.  What often happens is all too typical. The close tolerances designed in the racking-in mechanism can get out of tolerance through use if you so much as breathe on it wrong, or so it may seem. Even out of the gate as new equipment, they can be quite finicky birds requiring some TLC to keep them working smoothly.

The fix can be as simple as removing the front cover of the circuit breaker and lubricating the racking mechanism allowing its resets and mechanicals to function properly. The mechanism’s dogs can get stiff preventing the mechanism from seating properly.

In other cases we look for evidence the breaker may be over-racked in the racked-in position, throwing the interlock system out of alignment.

The circuit breaker proper may be out of alignment in its cell. This is very bad and runs the risk the load side connections (the finger clusters) may not be seated properly on the bus stabs. This is a nightmarish scenario if somehow the breaker manages to close and becomes energized.

When part of a good maintenance program, an air circuit breaker can be expected to delivery good reliable service for many years to come.

What is it about these breakers that people like so much? In a word, simplicity ─ they are quick and easy to work with.

Most breakers such as the Cutler Hammer EHD3100, to give one example, use “details” (mounting bus details) to attach the breaker line side to the panel board bus. Details are an additional item at a slightly greater expense and are not necessary for Square D I-Line breakers.  I-Line breakers line side connections are finger clusters which connect directly onto the panel board bus making swapping out an I-line breaker as easy as drinking a cup of coffee in the morning.

The process is pretty straight forward:

First up, de-energize the panel board and lock out and tag out the switch supplying power to the panel board. Check voltage to make sure the panel board is dead and that it is not being back fed through another source. Remove the panel board dead front. Loosen the load side lugs and remove the load side cables from the breaker. You now have access to the single mounting screw holding the I-Line breaker in place. After removing the mounting screw, place a screw driver in the prying slot on the mounting bracket on the load side of the breaker and pry the breaker horizontally away from the bus running vertically down the center of the panel board. The breaker can now be removed from the panel board. Put the new I-Line breaker in place and using a reverse prying motion, slide the breaker horizontally into position such that the line side finger clusters make complete contact with the bus. Insert the mounting screw and tighten firmly. Do not over tighten this screw as it is a sheet metal screw designed to hold the breaker in position only. Reconnect the load side cables, then go ahead and install the dead front back onto the panel board.

At this point it’s always a good idea to exercise the breakers in the panel board, working the action by opening and closing the breakers several times. With the breakers in the off position in the panel board you are now set to power back up.

MIDWEST has seen about every old obsolete circuit breaker there is.  We worry about the dangers of some breakers to those not familiar with circuit breakers. Some of these dangers are not present very often, but when they are, they could be lethal.  Here is a quick example of one such danger with molded case circuit breakers.  These are the plastic looking circuit breakers.  This danger usually occurs with three phase breakers.  The breakers have a plastic like toggle that is pushed up and down to turn a circuit breaker on and off.  Some circuit breakers with this toggle like handle are designed such that there is a metal stud that extends from the breaker into the toggle to give it support.  Occasionally the toggle breaks off leaving a visible metal stud sticking out from the front of the now defective circuit breaker.  This metal stud looks innocent enough.  You might even be tempted to use a tool on the stud to turn the breaker off or on.  Don’t.  On some breakers, the metal stud is actually energized at the full voltage of the middle phase.  That’s right, the metal stud is hot.  Shocking! And if you get between it and ground, you could be killed.  Whether old, new, or obsolete, if you find a breaker with a broker handle and there is an exposed metal stud, have a qualified electrician check it out.  The exposed stud would be hot when the breaker is closed, not when it is open, unless the breaker is back fed.  This is shocking news about some circuit breakers with broken handles.    

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. 

MIDWEST has Federal Pacific Circuit Breakers. Whether you are looking for a used or reconditioned Federal Pacific Circuit Breaker, MIDWEST is confident we can provide you with the breaker you need. All it takes is a phone call for our engineering team to jump into action. They get really excited when the phone rings and it’s a call for a Federal Pacific Circuit Breaker.

Click Here for Federal Pacific Circuit Breakers

We stock many Federal Pacific Circuit Breakers in our inventory. When calling MIDWEST for a Federal Pacific Circuit Breaker, be sure to have the catalog number available. This number is the key identifier for the breaker. If the cat number is not available, (nameplates can become time-worn or faded) other nameplate data such as a serial number or style number are often enough to find out the size and type of breaker you need.

We Solve Breaker Problems

MIDWEST has served the electrical community since 1977, the very same year the first oil began to flow through the Trans Alaskan Pipeline. Our experience has been invaluable in teaching important lessons about circuit breakers and power distribution equipment. Our engineers break out the high fives when they are able to solve a customer’s breaker problem. Give us a try. Our rapid fire technical team is standing by and waiting for your phone call.

For a complete list of Federal Pacific Circuit Breakers in our inventory visit our website at www.swgr.com. Call us soon and ask about our complete line of power distribution equipment.

10. Buying used bends the time/space continuum in your favor – you can trust us on this.

9.   Buying used extends one’s longevity, since you don’t have to worry about whether the

used piece of equipment will arrive on time.

8.   Buying used decreases the planets carbon footprint (go green) as the piece of equipment has already been made and is simply being put back into service.

7.   Buying used strengthens your marriage since now you will have more money to take your

spouse out to dinner more often.

6.   Here at MIDWEST Switchgear, special equipment needs are engineered to fit the customer’s

special applications.

5.   Only the used reconditioned equipment market can fill the need for existing equipment no longer

manufactured.

4.   Quality. Used equipment at MIDWEST is reconditioned and tested before it is shipped. Test results, be they megger, contact resistance, overcurrent, winding resistance, hypotential, or MIDWEST’s live load tests, must meet national specifications before equipment goes out the door.

3.   Warranty. Depending on the specific type of equipment purchased, a typical warranty on used reconditioned equipment is one year. The same time as the manufacturer’s warranty on new equipment.

2.   Availability. Manufacturers do not keep inventories of many types of new equipment. Lead times for new equipment orders can stretch from weeks to months. Used reconditioned equipment can be in your hands as fast as shipping and preparation allow. The operative word here at MIDWEST Switchgear is fast. Our goal is to get the equipment to the customer as fast as time permits.

1.   And the number one reason to buy used − On average you can expect to save up to 75% of the

cost of new equipment.