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What Do Westinghouse Housing Codes Mean?

On some Westinghouse air breakers, a special code is stamped on the nameplates which causes some confusion when replacing and maintaining the breakers in the field. It is called the “Housing Code” and is designated with a single letter. Ironically, the housing code was originally intended to avoid the very confusion that it is causing today. So, what is a housing code—and more importantly, what do we use it for today?

Breaking Down Westinghouse Air Breaker Housing Codes

In the 1960s and early ‘70s, a housing code was the factories designation to indicate interchangeability between circuit breakers within the lineup of switchgear as it was produced from the factory. Let’s look at an example. If you have a double-ended lineup of Westinghouse type DB air breakers and it’s designed with 3,000 amp electrically operated DB 75 mains, A DB 75 tie with 2,500 amp trips, and 12 1,600 amp, DB 50 feeders and the feeder breakers have trip units rated 1,600 amp, 1,200 amp and 800 amp, you might have the following designations.

The DB 75 mains all have the same control wiring and trip units and are both mechanically and electrically interchangeable, so they would logically both have a housing code of “A” stamped on them, as would any spare breakers on hand. The DB 75 tie is unique to the lineup because of the smaller trip unit, so it would have a housing code of “B,” as would a spare breaker if it was built at the time of the purchase. The 1,600 amp frame feeders are all mechanically interchangeable but have three different-sized trip units so they are not electrically interchangeable, the 1,600 amp breakers would all have the same housing code of “C,” the 1,200 amp breakers would be “D,” and the breakers with 800 amp trip units would all be “ E.”

This system ensured that operators had an easy way to identify interchangeability when the switchgear was new. However, housing code designations effectively became obsolete over the years with modern solid state trip units. These new solid state trip systems are more effective and accurate and much more adjustable than the original series overcurrent trips supplied by the OEM. They allow breakers that are mechanically interchangeable to also be adjusted to be electrically interchangeable with other breakers in the same line up. These trip units can and must be adjusted by qualified technicians to ensure that each breaker is set to protect each load safely and effectively.

This housing code continues for breakers in the medium voltage class as well but is less complicated. For example, if there is a lineup with 2,000 amp mains and 1,200 amp feeder breakers, the 2000s would all be designated “A” and the 1200s all designate “B” because they are all mechanically and electrically interchangeable. The overcurrent trip function is controlled by current transformers and panel mount relays and are separate from the draw out elements.


NPE: Experts in Used and Remanufactured Air and Vacuum Circuit Breakers

Whether you need help identifying circuit breakers or finding the right switchgear parts for your facility, NPE can help. Our extensive inventory of parts and expertise has made us to-go source for solutions for switchgear and circuit breaker needs. Go to our NPE on the Go mobile site or contact us today to talk about your needs and how NPE can help.

What “Obsolete Circuit Breakers” Really Means

Websters definition
ob·so·lete | \ˌäb-sə-ˈlēt, ˈäb-sə-ˌlēt\
Definition of obsolete
a: No longer in use or no longer useful // an obsolete word
b: Of a kind or style no longer current, old-fashioned // an obsolete technology

NPE’s definition
As relating to switchgear and circuit breakers… A product line not supported by the original manufacturer, but still commonly in use.

Why No Switchgear Parts are Really Obsolete

Many factories, government facilities, and large commercial buildings are operating on switchgear that is no longer supported by the OEM. The lights are still on, production is running, and everything is fine, until it comes to light that new parts are no longer available. What should you do?

Switchgear is one of those systems that represent a large financial investment. It’s physically large and often located in a basement, or on a rooftop or mezzanine. This makes it difficult to physically remove it if you decide to replace it and represents a large commitment of money, labor, and more importantly downtime for the building and systems. That’s time and money that could be better spent elsewhere. The solution to this problem is to find what you need on the secondary or used equipment market.

An “obsolete” General Electric AK-2-25 circuit breaker that can be found on the secondary or used equipment market.

Where to Find Obsolete Circuit Breakers and Other Used Switchgear Parts

Used switchgear dealers are often looked at as the first responders of the electrical market. They are intimately familiar with the equipment that the OEMs have obsoleted and can supply you with quality circuit breakers and parts, reconditioned to the highest standards and often upgraded with the latest materials and technology. Best of all, equipment is available with little or no lead time keeping your facility and production up and running.

At NPE, we have a saying that “nothing is obsolete.” Not only do we have thousands of circuit breakers, switchgear, and parts in stock and available at a moment’s notice, we also offer solutions for over 300 of the most troublesome, hard-to-find parts. This gives you new aftermarket replacement parts with design and material upgrades to keep your switchgear up and running better than ever. Our inventory includes items that go back to the 1940s and our staff has the experience to provide cost effective solutions for repair, upgrade your equipment, and extend its useful lifespan almost indefinitely.

Need a solution for your switchgear problems? Submit information about what you need on our NPE on the Go mobile site or contact us today to talk about your needs and how NPE can help.

The Benefits of Renting or Exchanging Reconditioned Circuit Breakers from NPE

National Power Equipment is more than just the go-to circuit breaker supplier for used and remanufactured air and vacuum circuit breakers. In addition to selling breakers, NPE also offers a convenient rental circuit breaker program for facilities that either don’t have sufficient spare breakers or want to avoid down time caused by outages.

The reasons for needing rental breakers vary, but it typically involves when a facility reaches a certain point in its maintenance schedule or if a breaker needs to be fixed. When those times come, NPE can provide your facility with a rental breaker ready for service or set up a rental breaker exchange based on your specific needs and timeline.


Rent Breakers Ready for Service

When you rent a breaker, NPE will make sure to have it ready to put it into service. NPE will work with you to meet your breaker specifications so that your rented breaker is completely interchangeable. NPE regularly keeps a “fleet” of low-voltage breakers in stock and ready to go at a moment’s notice, which means we can sometimes ship out your rental breaker the day it’s requested. If the breaker isn’t already in the rental fleet, we can typically recondition your required breaker and ship it out in three to five days. Stock rotates quickly, so make sure to check with us about availability.

Rentals are priced on a per-month basis, plus freight for shipping. NPE can work with you to not only determine which rental breaker options are interchangeable for your setup, but also which are the best for your budget. For example, manually-operated breakers are a less-expensive option than electrically-operated. In turn, we generally recommend manually-operated breakers for savings purposes unless the breaker is meant for use with a generator, transfer scheme, or other similar situations.

Rental Breaker Exchange

The rental breaker exchange program is a good option for service shop customers that don’t want to take on a series of outages. In this scenario, NPE provides used, EOK breakers that the customer can recondition and retrofit on their own. Once the customer is ready to swap out the breakers, NPE’s breakers are exchanged with the customer’s breakers during a single outage rather than several. This single exchange limits the amount of overall downtime and the labor involved with repeated exchanges.

Rent Circuit Breakers from NPE

Whether you need a short-term solution for a single breaker or want to swap out 10-15 as part of a maintenance schedule, NPE can provide you with a rental solution for your needs. Contact us today to talk to one of our experts about our rental program.

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 to ITE in 1928 after the inverse time element that plays a key part in every overcurrent trip device.

The shared history of ITE, BBC, and ABB began more than half a century later. 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. The collective rebrands and mergers mean that while different circuit breakers and parts may have separate ITE, BBC, and ABB nameplates, many of these parts may be viable replacement options for outgoing equipment.

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.