Understanding Square D Circuit Breaker Part Numbers

Square D breakers are some of the most popular breakers on the market today, and have been popular for many years. Commercial Square D breakers use a complicated numbering scheme that can be very beneficial to understand. These methods apply to both new and used breakers.

First, we’ll look at a common Square D part number that is available as a new or used breaker, the Square D KA36200.

Frame type: K

Interrupt: A

Termination: –

Number of Poles: 3

Volts: 6 (600)

Amps: 200


As you can see in this example, the part number KA36200 means it is a type K frame, standard interrupt, 3 poles, 600 volts, and 200 amps. These types of breakers usually come in several different varieties, most commonly with different amperages. A 300 amp breaker would be numbered as KA36300.

Square D offers many frame types. The frame type determines the size, shape, and style of the breaker. The interrupt has several options. A=Standard, C=Extra High, I=Current Limited, Y=Standard(F-Frame only). Terminal options are None=I-Line, F=No Lugs, L=Lugs on both ends, P=Lugs off end.

The suffix offers many options:

F=Frame Only

G=Ground Fault


M=Molded Case Switch

MT=Top Feed Lugs

V=View Window

By understanding this numbering scheme, you can decipher the part on any Square D breaker. If you have a KA36070, but need to install a 100 amp, you would know to order a KA36100.

For residential breakers, the Square D QO frame type is the most popular. Square D breakers are available at home improvement stores and at stores online. Many online stores also sell used Square D breakers. These used breakers are viable options when an electrician cannot purchase a replacement breaker through traditional electrical stores. When a homeowner is faced with replacing a residential circuit breaker, they most often can locate a replacement from a local hardware or electrical supplier.

If you are replacing a Square D breaker and you require a breaker with a suffix on it, the only option may be to buy one directly through Square D. Many of these breakers fall into the class of custom order breakers and are only available from Square D, and often are custom built if they are not readily available in stock at a warehouse.

Square D has long been a pioneer in new and used breakers. In 1951 they released the first plug-in style of breaker- a style that is still in use today. In 1991, Square D was bought by a French company, Schneider Electric. Schneider Electric continues to use the Square D name for all US market breakers. Even though Square D is owned by a different company now, their quality and product availability is second to none.

Square D breakers are available at nearly all home improvement stores, hardware stores, and online from breaker suppliers. Many breaker suppliers offer both new and used Square D breakers. Some stores specialize in obsolete and used Square D breakers.