The General Electric Magne-Blast product line was produced with a wide array of shapes, sizes, and ratings. Finding interchangeable breakers can be simplified once you break the line down to a few simple rules.

How to Determine if a GE Magne-Blast Breaker is Interchangeable

There are multiple factors that you can check to determine whether a General Electric Magne-Blast circuit breaker is interchangeable or not. These include:

• Single coupler vs. double coupler
• Solenoid vs. stored energy
• Voltage/MVA Rating
• Frame size

Single Coupler vs. Double Coupler

The secondary coupler or secondary disconnect is a device/plug that carries the power that controls the breakers opening and closing circuits. You can tell the difference between original and newer breakers by the following characteristics:

• The original breakers are equipped with 2 round, 7 pin couplers that mount on each side of the mechanism.
• The newer breakers have a single square coupler with 16 pins that mounts on the left-hand side (as you face the breaker).

These two breakers are not interchangeable

Solenoid vs. Stored Energy

Older breakers are equipped with a large closing solenoid that closes the breaker, this mechanism type typically has an “MS” designation, like MS-5, MS-7, MS-10B1, or the most common designation MS-13. Newer breakers are equipped with a spring charged/stored energy mechanism, most commonly, the ML-13. This mechanism uses a motor/gearbox to compress springs that are released to close the breaker.

The primary advantage of the stored energy mechanism is that it draws much less current to close the breaker. These breakers have a limited interchangeability. More modern ML-13 breakers can sometimes be used to replace old MS style breakers. When produced at the factory, these replacement breakers will have a “C” at the end of the model number (e.g. AM 4.16-250-6C). Minor changes will also need to be made in the cell wiring when using this replacement because of the decreased power that it takes to close the breaker.

Voltage/MVA Rating

The next thing to look for is the MVA rating of the breaker. This is designated in the model number after the voltage rating. For example, the model number AM 4.16-250-6C is a 250 MVA rated breaker. These lines Magne-Blast circuit breaker product lines include:

• 50/75MVA
• 100/150/250/350 MVA
• 750 MVA
• AM 13.8-1000

50/75 MVA Magne-Blast Product Line

The smallest of the product line is the 18-inch wide 50/75 MVA breakers. Designated as either AM 5-MVA or AM 4.16-MVA, these breakers all had one of various vintage MS style solenoid mechanisms. They are available in 600-amp and 1,200-amp frames and are backwards compatible. For example, an AM 4.16-75 1,200-amp breaker can be used in place of an AM-5-50, but not the other way around.

100/150/250/350 MVA Magne-Blast Product Line

The next step up are the 100/150/250/350 MVA breakers. These are built on slightly wider, 26-inch frames and are very common in commercial and industrial facilities. They have the same limited backwards compatibility of ML-13 to MS-13 mechanisms outlined above and all but the 350 MVA have a backwards compatibility of MVA, as well. In other words, a 250 MVA can always be used in place of a 150 MVA but not the other way around. The 350 MVA’s are built on a taller frame and are unique.

750 MVA Magne-Blast Product Line

The larger 36-inch-wide breakers cover both the 7.2 kv and 13.8 kv range which are not interchangeable with each other, but generally carry the same interchangeability of their smaller 5kv brethren. The exception comes in the 750 MVA frames.

The original 750 MVA (e.g. AM 13.8-750-2) is on a much taller frame than the 500 MVA or below breakers and is commonly known as a “tall boy.” Its added height is unique. However, GE did make a replacement later in production that is designated with an “L” at the end of the nameplate, AM 13.8-7505HL, which indicates a shorter lower profile breaker that was factory modified to fit into the ‘tall boy” cell.

AM 13.8-1000 Magne-Blast Circuit Breaker

The final breaker, the AM 13.8- 1000 is unique and not interchangeable with the others. There are two basic versions the AM 13.8 100-3H and 4H. The “3H” is commonly called the humpback breaker because the box barriers and arc chutes are taller in the back. The “4H” has smaller arc chutes and is interchangeable with the “3H”, but again, not the other way around.

Frame Size

Always make sure that breakers are replaced with replacements of the same frame size or extensive damage could result. These frame sizes are:

• 600
• 1200
• 2000
• 2500
• 3000
• 3800

Need Help Finding Interchangeable Breakers?

Still confused? We can help. Take a photo of your nameplate and contact us or use NPE On The Go to get all of the information needed to get a quote a replacement.

Trying to find a way to extend the life and reliability of your GE Magne-Blast switchgear instead of looking for a replacement? Learn more about how NPE’s bottle repotting program can be just what you need. If you need help identifying Magne-Blast circuit breaker designations, read this post to find out where to look.

General Electric produced a line of medium voltage air circuit breakers called the MAGNE- BLAST for over 30 years. This product line was very popular from the late 1950's through the early 1970s and was produced in a wide range of sizes and ratings to meet customer’s needs. From 2.3kv through 15,000 vac and from 50MVA interupt through 1500 in frame sizes from 600 amp through 3000 amp, this line covers a wide range of needs. These breakers are known as "Verticle Lift" breakers because they must first be lifted vertically to engage the primary line and load connections. These connections are made inside of  porcelain "bottles". The breaker to bottle connection alignment is critical and can cause failures if misaligned. 

Particular attention needs to be paid to several parts of the nameplate when you’re looking for replacement MAGNE-BLAST breakers or parts for these GE circuit breakers. This flow chart was designed to streamline the specification process and help you identify your MAGNE-BLAST designation.

Even with the flowchart, it can still be easy to miss specifics for designation There will be additional information that you will need. Rated Amps, close and trip voltage, and mechanism type can all be found on the nameplate. When in doubt, a photo of the nameplate and a photo of the breaker from the front will give your supplier a clear understanding of what you need. The following photos of MAGNE-BLAST nameplates show how important details like the letter suffixes are in determining exactly what you need.

Still confused? Contact us today or try our Mobile Ap- NPE on the Go  and we’ll help your figure it out. As a circuit breaker supplier, that’s what we’re here for.

Finding old or obsolete General Electric circuit breakers can be challenging. GE has produced circuit breakers for over 70 years, which can make it difficult to match the right models and model numbers to your needs. In this article, we’ll present a brief history of GE’s circuit breaker production and help you understand how to identify what circuit breaker you’re looking for.

A Brief History of General Electric Circuit Breakers

GE’s “Slate back” line of type AE and AL air circuit breakers was its first product line utilizing one of the first true inverse time elements to obtain automatic “resettable” overcurrent protection. These breaker lines have generally been upgraded since the original series overcurrent trip units with solid state trip units or retrofilled with more modern breakers  Sometime later, technological improvements prompted a redesign. GE iresponded by ntroducing the AK line of breakers. These models featured improved electro-mechanical trip units and were designed to fit both AKD and AKD5 switchgear.

In the 1980’s, GE redesigned the AK line and gave the product line the AKR prefix. Although they may initially seem similar in appearance to the older style, the AKR design has been improved and is not interchangeable with previous versions. This product line was designed to fit both AKD6 and the later redesigned for future vintages righ up through AKD10.

As products and technology continue to evolve through the Wavepro and AKD 10 up through and including Entelliguard and AKD 20 switchgear. These changes make it very important for users to be able to read breaker numbers to identify which type of breaker model they need.

How to Read a General Electric Breaker Number Basic Designation Chart

All of  the digits in an AK or AKR model number identify important characteristics of the breaker. It is important to either understand these details or be able to relay that information to a supplier that has a working understanding of them.

When it comes to reading and understanding an AK or AKR breaker number, let’s start by using an AK-25 circuit breaker as an example. At a glance, with the door closed, most AK-25’s look the same, but the missing digits between the AK and 25 reveal important information that is needed to assure a safe and proper fit. You can use these quick guidelines to identify the specific model of a General Electric circuit breaker:

4 Steps to Identifying GE Circuit Breaker Model with the 

1. The first part, “AK”, tells you the general designation of one of two switchgear vintages that the breaker will fit in - AKD or type AKD 5.
2. The last part, “50”, indicates one of the smaller feeder breakers that is rated 1600 amp AC continuous and has a frame rating of 50,000 amps interrupt (AC). 
3. There are up to 4 more spaces for letters or numbers between the AK and 25 that are important.
   1. One could be a “U” which would indicate the addition of current limiting fuses.
   2. Another could be an “F” which designates a special field discharge option.
   3. There will be a number, most likely a 2 but it could be a 3, 4, all the way up to 10, which designates which type of trip unit that was installed at the factory.
   4. After the 2 or other trip unit number there could be an “A”. Absence of an “A” indicates that it is for AKD switchgear, the presence of it indicates it is for type AKD5 switchgear.
4. For more information on how to understand what each letter or digit of the model number means, we’ve developed a guide. This guide will help you identify most of the options built into your breaker from the factory and which, if any, will need to be changed or upgraded.

Other Questions to Ask When Identifying Type AK and AKR GE Circuit Breakers

In addition to knowing the brand and product number you’re looking for, here are some other questions to help identify the perfect solution for your needs:

• Is the breaker A. electrically or B. manually operated?
• If A, what is the voltage of the close coil, control relay and trip coil?
• If A, do you have a wiring diagram number? 
• Why type of trip unit is needed?
• What trip function is required?
• Are any accessories like bell alarm or under voltage protection required?

To download this chart click here: flowchart for AK and AKR circuit breakers  If you’re still having trouble or are unsure of what you need, just let us know and we’ll be happy to walk you through the process.