What Everybody Ought to Know About Square D Breakers

Circuit breakers are an important part of modern life. Without circuit breakers, electricity as we know it would not exist. We would be unable to power our homes and businesses with an unending and variable flow of electricity. Circuit breakers regulate this flow of electricity and put a stop to any current that threatens the safety or function of the breaker.

square d breakers

What Is Square D?

Square D is an American electrical equipment manufacturer. The company was originally founded in 1902 by two electrical engineers. In the developing years of the company, Square D provided a range of electrical products and equipment.

However, in the 1920s, Square D sold much of its business to focus on circuit breakers and safety switches. They alerted the public to safety concerns in regards to electricity and began producing a range of circuit breakers to residential and commercial areas. Schneider Electric, Square D’s parent company, has provided engineers with electrical equipment since 1836. Suffice it to say, they know what they are doing.

Square D is a big player in the residential and commercial breaker market. The company offers several popular lines of circuit breakers with different applications and characteristics. It is important to consider the end use when deciding on a circuit breaker.

When replacing one, or performing maintenance or inspection on a breaker, it is important to understand what type of breaker you are dealing with.

Qwik-Open Miniature Circuit Breakers

The Square D “QO” line of miniature circuit breakers is their best-known product line. These “Qwik-Open” or QO breakers are the fastest opening breakers in use in the industry. They reportedly open after just one full power cycle of a 60 Hz AC line (about 1/60th of a second). These breakers feature a visual trip indicator and make it easy to quickly spot the tripped breaker in the panel.

Qwik-Open Bolted Circuit Breaker

Another popular breaker by Square D is the QOB breaker, which stands for “Qwik-Open-Bolted.” These breakers have screws that secure the breaker into the panel; therefore, they are much harder to accidentally pop out when changing other breakers. Conveniently, an electrician can easily clip a QO breaker into a QOB panel and provide some versatility.

HOM Circuit Breakers

HOM is another line of breakers. They much less costly and could be more economical to use in your home. However, it is important to note, these breakers do not offer a visual trip flag or the fast-trip feature. These breakers are also not physically interchangeable with QO breakers.

Easy Installation of I-Line Series

Many electricians like the popular I-Line series Square D breakers. Many in the industry favor this specific series of distribution panelboards and breakers. These panels offer easy installation of new breakers. Electrical professionals can install the breakers by simply using a flat blade screwdriver.

The panel employs what is called a “stacked bus system” that protects the energized bus from accidental contact. The breaker can be installed by touching only de-energized parts of the backplane on the panel.

Though I-Line series panels are convenient and common for electrical contractors, it is important to ensure the correct phase rotation is employed. The right side of the panel, where there are even numbers, has phases in a C-B-A configuration. The left side with the odd numbers on the panel has a standard A-B-C arrangement.

square d panels


Double Tapped Design

Another thing to consider when working with Square D breakers is that some of these breakers can safely be double tapped. This is when one screw or terminal inside of a panel connects two conductors. Only Square D and Cutler Hammer design circuit breakers this way, but not all of their breakers look this way.

If it can be safely double tapped, the breaker will have two places for wires to connect and have a picture on the breaker of two wires. Other breakers cannot be safely double tapped. Breakers that are not set up to be double tapped will state on the breaker that it is one-pole.

If a single-pole breaker is double tapped, you are putting yourself at risk for arcing, overheating, and fires. Not all Square D breakers can be double tapped, so it is important to understand what kind of breaker you are using.

Electrician at work

Final Thoughts

Residential and commercial applications most commonly use Square D breakers. It is important for homeowners and electricians to know what kind of breaker they are dealing with since they are so common.

Wiring a breaker incorrectly can result in arc shocks that can be fatal, as well as fires and overheating of the circuit panel. If you feel overwhelmed or feel that you are out of your league, consult a licensed professional to help with installation or repair.