Galvin Power is reader-supported. When you buy via our links, we may earn a commission at no cost to you. Learn more

QO vs QOT Breaker: Which is a Better Choice?

Writen by Edwin Jones

Fact checked by Andrew Wright

qo vs qot breaker

You’re wiring an electrical service panel and you’re curious about using QO vs QOT breakers. But what’s the difference between the two?

A QO circuit breaker has features that allow for quick detection if a trip occurs. As for the QOT breaker, it has similar traits to a QO model but with a slim design, allowing two units to fit in a compatible bracket.

Take note that the above isn’t the only difference between QO and QOT circuit breakers. So keep reading to learn more about these devices.

Compare In Detail

What Is A QO Breaker?

square-d-qo-2-pole-tandem-breaker

QO stands for Qwik-Open, and it comes from Square D’s mini circuit breaker line. The reason behind this terminology is its quick-opening feature. It trips after 1/60th second, allowing users to prevent electrical faults almost immediately.

Keep in mind that QO breakers are generally newer models compared to QOT circuit breakers. You can typically spot a QO breaker if it’s without hook.

Make sure not to confuse QO with QOB breakers. For example, a QO2020 breaker might not have a bolt-on connection that a QOB2020 circuit breaker may possess.

What Is A QOT Breaker?

qob-tandem-breaker

Called the Qwik-Open Tandem breaker, the QOT circuit breaker uses two single-pole thermal magnets. Its design allows the use of two QOT breakers on one compatible mount.

Certain QO breakers have current ratings of 20/30 amps. Meanwhile, QOT breakers are often rated at 15 and 20 amps.

Take note that old QOT breakers may not fit service panels that accept QO breakers. So don’t make the mistake of buying a QOT breaker with hook as it might not go into a breaker box meant for QO circuit breakers.

Also, you may find a QOT2020 breaker marked as a QO/QOB tandem breaker. If you find the naming confusing, ask a reliable electrician or the breaker’s manufacturer if you’re unsure about product compatibility.

How Does It Work?

Both QO and QOT circuit breakers should work like regular breakers. In other words, these models should help control the supply of power to connected electronic devices.

Also, these breakers should trip if the current exceeds a predetermined limit. When this happens, the connected appliance, machine, or device won’t experience significant harm.

Pros And Cons

square-d-qo-breakers-tandem

Both QO and QOT circuit breakers have pros and cons. However, QO breakers are often ideal for up-to-date service panels.

It’s still possible to use QOT breakers today. But some installers may find it more challenging than intended to fit these breakers into new breaker boxes.

Also, QO and QOT breakers are often more expensive than other models, especially when compared to Homeline breakers. So these Square D breakers may not be ideal fits for interested buyers following strict budgets.

Differences

old-style-square-d-breakers

Aside from the physical dimensions, QO and QOT circuit breakers often have different maximum amperes.

In particular, a QO single-pole breaker often has a maximum amperage of 70 amps, and its two-pole line may have up to 200A.

However, Square D QO 2 pole tandem breaker is more limited in rating at 15A, which is somewhat similar to the 15 and 20 amps of QOT molded breakers.

Another difference between the two lines can be found if you compare the QOT2020 vs QO2020. The former is newer than the latter, though both are for QO load centers.

Despite these disparities, both lines have products that work with the QOTHT handle tie from Schneider. For example, you can connect two QO 20/20 breakers or two QOT2020 breakers using this accessory.

Frequently Asked Questions

will-a-qo-breaker-fit-in-a-homeline-panel

Are QO And QOT Breakers Interchangeable?

Certain QO and QOT circuit breaker models are interchangeable. However, certain load centers, such as those that use Plug-on Neutral (PoN) designs, might only accept Square D QO breakers tandem.

What Breakers Are Interchangeable With QO?

Different breakers are interchangeable with QO, and these models may come from various brands. You can find a list of compatible breakers in the next section.

What Breakers Are Compatible With Square D QO?

Square D QO compatible circuit breakers include those that come from brands like:

  • Cutler Hammer
  • Siemens

Note that the products from the above brands should be UL-classified, or they may not be interchangeable with your QO device.

If you use old style Square D breakers to replace your newer QO, they may not fit newer enclosures.

Will A QO Breaker Fit In A Homeline Panel?

You can not interchange Homeline breakers with other brands and Square D QO circuit breakers. So no, QO breakers won’t fit onto the slots meant to hold Homeline models.

Conclusion

Comparing a QO vs QOT breaker often only presents slight differences between the two lines. Perhaps your main concern would be to ensure that the circuit breaker that you’re about to install is compatible with your service panel.

One way to find out if you should use a QO or QOT breaker is to look at your panel’s instructions. They will have a list of CB models you can choose from.

5/5 - (2 votes)