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Westinghouse DA Circuit Breaker Line

George Westinghouse was one of the primary innovators of the Industrial Revolution and of the electrical power distribution and control industry that developed along with it. His company continued to spearhead innovations created by inventors such as Edison, Tesla and others which included polyphaser motors and the first resettable circuit breakers made with interchangeable parts. This product line is commonly known in the industry as Westinghouse slatebacks or the DA series of breakers. They both used thermal and inverse time overcurrent trip devices that sensed an overload condition and safely tripped to open the circuit to prevent damage to infrastructure, equipment as well as injury to personnel. Once the circuit was safely de-energized, technicians could locate and clear the cause of the fault and re-energize the circuit with minimal efforts.

Westinghouse Slatebacks or the DA Series of Breakers

This product line consisted of a robust current path mounted on a heavy slateback board and integrated into both live front and later dead front (enclosed) switchgear sections. Although this product line was advertised to have interchangeable units and parts, there was a wide variety of products to choose from and variables could only be identified by technicians familiar with the equipment, including changes caused by products marketed by a budding OEM of the time. In order to weed through these issues I will begin with the basics and fine tune the details as we go. Of course, if you need one of these quickly and don’t want to get bogged down in the weeds, just contact one of our experts at 800-647-0815 or use NPE’s “On the Go” tool - M.NPEINC.COM.

The basic product line came in 5 different designations, defined by how many amps each could be relied on to interrupt safely, based on standards in place at the time. These are DK 15, DK 25, DA 50, DA 75 and DA 100. Each of these breakers could be provided in either a drawout or bolt-in frame. These breakers were built to last and it’s not unusual to see them still in service today with upgraded electronic trip units. The bolt-in breakers are the toughest to identify and replace because they have often been incorporated into large control panels with various other controls. Things like size and placement of the bus, vertical or horizontal bus alignment and number of phases along with field discharge legs are a few of the criteria which must be identified and are best done with photographs and sketches along with the technical details.

The drawout breakers, while they still needed to be carefully examined, are much easier to identify and replace. The vast majority of them (say 98%) worked with a standard design that George Westinghouse was proud to put his trademark on. More on the other 2% later… 

Westinghouse Drawout “DA” Style Slateback Breaker Types and Sizes:







DK 15


225 amps


Finger cluster style does not affect interchangeability as long as they are for round bus**.

DK 25


600 amps


Finger cluster style does not affect interchangeability as long as they are for round bus**.

DA 50


800, 1200 and 1600 amps


Frame size is not indicated by the nameplate on the front of the breaker. The breaker nameplate indicates the rating of the trip unit as supplied from the factory. Frame size, can be best be identified by the size of the round copper stab that the finger clusters are mounted on 7/8” for 800, 1 ¼” for 1200 and 1 5/8” for 1600 amp. Electrically operated breakers are in no way interchangeable with manually operated breakers. The 800, 1200 and 1600 amp frames are not interchangeable.

DA 75


2000, 2500 and 3000 amps


Finger cluster style does not affect interchangeability as long as they are for round bus**. Frame size is not indicated by the nameplate on the front of the breaker. The nameplate only indicates the rating of the trip unit as supplied by the factory. Frame width varies between two sizes and finger cluster/back stab arrangement can also vary between 6 stab and 12 stab versions on a “standard” three phase breaker. The only reliable way to identify the breaker is with a measurement of the width and to photograph or otherwise visually inspect the back of the breaker.

DA 100


various 4000-12,000 amps


Frame width varies and finger cluster/back stab arrangement can also vary between 6 stab and 12 stab versions on a “standard” three phase breaker. The only reliable way to identify the breaker is with a measurement of the width and to photograph or otherwise visually inspect the back of the breaker. This is a very rare breaker in today’s world. Engineers of the day theorized that anything above a 100,000 amp fault was impossible and used the base DA 100 design with a variety of ever increasing frame sizes. 4000 amp is the most common. Use all of the above guidelines to identify your application.



image of DA-50 manual circuit breakerimage of DA-EO westinghouse circuit breaker




**The Other 2 Percent:


The above guidelines will help you identify the correct replacement for your Westinghouse slateback breaker 98% of the time. However, “back in the day”, Westinghouse also sold its stationary breakers to Allis Chalmers for use in its own OEM version of switchgear. Allis Chalmers would take stationary breakers, with flat stab (and all of the variables associated with them) and add their own finger clusters and drawout hardware. This resulted in a drawout circuit breaker with finger clusters designed to mount on flat bus rather than the standard Westinghouse round stab as noted above. To complicate matters, the Westinghouse factory nameplates remained on the breakers and no outward indication was given that they have been modified by an OEM and not interchange with standard factory breakers.

In conclusion,please keep in mind that equipment of this era was made during a period of time when the idea of standards for interchangeable parts left some room for interpretation. It will take a supplier with experience and an eye for detail to ensure that the your equipment fits and functions the way that George Westinghouse’s company intended, like the professionals at NPE. We’re breaker geeks -this is what we do. Contact us or use NPE’s “On the Go” tool and have it guide you through all of the steps you will need to find the right breaker for your job.

               image of westinghouse DA circuit breakerimage of DA-75 flat stab circuit breaker                                







What's the Difference Between ITE, BBC, and ABB Breakers?

It’s not always easy to find the right old or obsolete electrical equipment for your facility. Over the years, there have been several manufacturers of large industrial switchgear and circuit breakers that have come and gone, which can make it difficult to track down specific equipment.

Three of these manufacturers are ITE, BBC, and ABB. At first, they may seem like different companies, but many of their breakers are interchangeable with each other. That’s because there’s really no difference between the three companies aside from when and where they were founded.

          An ITE K 800s circuit breaker             A BBC K 800 circuit breakerAn ABB K 800 circuit breaker

The Shared History of ITE, BBC, and ABB Breakers

While ITE, ABB, and BBC all have different names, they’re all a part of the same history. The timeline starts with the ITE Circuit Breaker Company, which was originally known as the Cutter Electrical Manufacturing Company when it was founded in in 1890s. ITE has a history of innovation, so much so that the company rebranded in 1928 after the inverse time element that plays a key part in every overcurrent trip device.

After decades in business, ITE merged with Brown Boveri Electric Company, an American operation of a Swiss-based company. In 1984, the company changed its name to BBC Brown Boveri Inc. and began nameplating its breakers “BBC.” Four years later, the company completed another merger, this time with a Swedish business called ASEA. The resulting new company was renamed ASEA Brown Boveri, which was shortened to ABB Inc over time.

Find the Right ITE, BBC, and ABB Breakers

While ITE, BBC, and ABB breakers can be grouped together, you still need to find the right breakers or breaker parts that match your exact needs. As a used electrical equipment dealer, we have thousands of reconditioned circuit breakers and aftermarket parts for ITE, BBC, and ABB equipment.

If you can’t find what you need on our main site, you can submit information about what you need on our NPE on the Go mobile site or contact us today to talk to one of our experts about finding the rights solution for your needs.

Are Eaton, Westinghouse, Square D, and Cutler Hammer Breakers Compatible?

The search for old or obsolete circuit breakers isn’t always easy. Many factories and government or commercial facilities operate on electrical equipment that is no longer supported with new parts, which means you need to either find a remanufactured air or vacuum circuit breaker or aftermarket breaker parts that are a match for your equipment.

There are several companies that have manufactured breakers in the past century and beyond, but you typically can’t swap out one competitor’s breaker parts for another’s. However, there are some instances where one brand of breaker is nearly identical. Westinghouse and Eaton are two such examples.

Circuit breaker with Eaton nameplateCircuit breaker with Westinghouse nameplate

Why Does Eaton and Westinghouse Have Compatible Breakers?

The answer is simple: the same company owns the production rights for both Eaton and Westinghouse. Westinghouse had a low-voltage air circuit breaker line. The company sold the rights to this product line to Square D, which then sold it to Eaton Corporation. As a result of rights ownership, there are nearly identical breakers with four different nameplates on them:

  • Westinghouse
  • Square D
  • Eaton
  • Cutler-Hammer

These breakers can be compatible with each other despite the different nameplates, as certain models are largely the same aside from some upgraded electronics.

Circuit breaker with Square D nameplateCircuit breaker with Cutler Hammer nameplate

Find Old and Obsolete Eaton and Westinghouse Breakers

While you now know that Eaton breakersWestinghouse breakers, Square D breakers, and Cutler-Hammer breakers are largely compatible, you still need to find the exact models you need for your facility. At NPE, we have amassed and refurbished old electrical equipment, including breakers and aftermarket parts for Eaton, Westinghouse, and more.

Ready to find the right breaker parts for your facility? Submit information about what you need on our NPE on the Go mobile site or contact us today to talk to one of our experts about finding the rights solution for your needs.

The DS Switchgear Line


Image of DS Switchgear

The DS line of air circuit breakers has been a tried and tested product line of low voltage air circuit breakers that have been proven to be both versatile and reliable for decades. Originally, it was sold as a Westinghouse product, then the line was later sold to Square D and then Eaton Cutler Hammer.  It is widely understood that all of these breakers are interchangeable regardless of label, however the same does not hold true when replacing the switchgear parts. The switchgear cabinets have been manufactured in several locations around the country which resulted in six different lines of cabinets.  Care must be taken to properly identify which style of cabinet is in question to properly identify and acquire interchangeable parts.

The first vintage of DS switchgear was manufactured by Westinghouse in East Pittsburgh in 1969 and continued through 1973. It can be identified as having “Shop Order” (SO) numbers that start with “24Y”. The second vintage also made in East Pittsburgh through 1984 with SO numbers that started in “27Y” and concurrently with “WPA” switchgear made in St. Louis and was designated by a “General Order” (GO) number rather than a shop order number. The East Pittsburgh gear was generally marketed to heavy industrial users and the WPA gear for commercial applications.

Two more vintages came out of the St. Louis plant, designated as vintage III and IV. Vintage III was an attempt to merge the “27Y” product line with the WPA product line and it is usually designated with a prefix of “28Y”. It was a very short production run during 1984 from May through October. Vintage IV was made in St. Louis form October 1984 through May of 1990 - it continued to use the GO number system and also the “28Y” SO numbers. In 1990, production was moved to Asheville, NC and although changes had been made to the design, the “28Y” SO number system was continued.

Finding Replacement Parts for DS Switchgears

If this sounds confusing, you have a lot of company. So how does someone go about finding replacement parts to maintain their DS switchgear? If you are fortunate enough to have the original product literature (see below) it will help to some degree. However, because much of it is no longer manufactured (new) you will more than likely find yourself relying on a reputable used electrical equipment dealer like NPE. If you know the SO number, GO number and production dates it will help narrow the focus, but even within product lines things like bus size and length will change depending on the configuration and rating of the switchgear.

Cutler Hammer DS and DSL Low Voltage Power Circuit Breaker Renewal Parts -  Manual RP.22B.01.T.E.

Westinghouse Instructions for Low Voltage Power Circuit Breakers Types DS and DSL – Manual  IB 33.-7901G

Instructions for Type DS Metal-Enclosed Low Voltage Power Circuit Breaker Switchgear Assemblies – Manual IB 32-690-E

The fastest and most reliable way to get the right part, at the right price, at the right time will be with photos and measurements using the NPE "On the Go" with your smartphone. NPE "On the Go" is very easy to use, just open it up and navigate to Switchgear/Switchgear Parts, answer the product driven questions and attach photos that you’ve taken with your mobile device. This RFQ will be sent to the NPE technical staff where it will receive TOP PRIORITY! Of course, you can still contact us with your requests and questions.      


NPE "On the Go"



Technical Manual Database Online

Our Technical Manual Database is Available Online

Customers have long recognized that used electrical equipment dealers stock a broad range of vintages of switchgear and breakers which makes them an invaluable source for technical support. The staff at NPE has spent decades offering assistance to our customers due to our training and hands-on experience with the thousands of breakers that we stock. Over the years we have gleaned expertise along with thousands of manuals and catalogs so when you have a problem we can assist you with finding a solution.

We have decided to take that technical support to a new level by giving you unlimited access to our technical manual database. You now have over 5,000 manuals at your fingertips and that list is continually increasing. You can access this 14GB database by visiting our website at

Although, we realize that not everything can be found in these books and/or you just might not have the time to wade through them, so as always, we are here for you. Contact us and we’ll help you get the information you need quickly.

NPE technical manuals