QO twin breakers, two styles ?

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Stevenfyeager

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United States, Indiana
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electrical contractor
Where have I been for the last 20 years ? I thought QO twin or tandem breakers had the metal 'hook' like steel at the screw terminal end to keep people from trying to use them in QO panels that arent made for twins. But today, at a job, I saw a twin that did not have the metal 'hook' but instead had a snap in latch like regular QO breakers. All of the twins I have bought over the years had the steel hook. And in all the panels that did not accept twins, other electricians had broken or cut off that steel hook to get them installed (modified, contrary to code). And those twins were very loose and dangerous. But, today, to my surprise, for $60, my supply house said they sell these non-hook twins.
Does this mean all QO panels accept twins ? And all the electricians over the years that had been breaking the steel hooks off didn't have to do that ? They make a twin that simply snaps in like all regular breakers?
 
Only the original listing of the panel will determine if it (legally) accepts tandems, and which type. And how many.

With Square D panels, the catalog number is usually a good starting point. If there's a 4-digit number like 2020, 2030, 2040, 3030, 3040 etc, the first two digits tell you the number of spaces, and the last two the total number of circuits allowed. So a 2020 panel will not take any tandems, a 2030 will accept 10 tandems (usually the bottom 10 spaces) and a 2040 panel will take a tandem anywhere.
 
Thanks, the model no. was no help, it started with QO , but followed by no numbers, just letters. The fine print for types of breakers was missing. My young helper (1 1/2 years with me) had photoed the breaker label yesterday and I notieced it had dotted lines for each space as if each breaker space allowed two labels, sometimes in panels that matches twin capabilities.
When I showed my helper that my twin with the hook would not fit, I said we can't use a twin. But then I saw the installed twin sitting perfectly. (with the two snaps), I removed it and saw it was just like a regular breaker. Home Depot and Lowes only sell the 'hook type' twin and so I'd never seen this type of QO twin before. That's when I called the elec supply house. "Sure, Steve, we sell those, $60." Thought I was going to teach my young helper something but I was the one who had to learn.
 
The tandem breakers with the rejection features are called CTL breakers, and cost less than their non-CTL counterparts.
 
Stevenfyeager said:
Thanks, the model no. was no help, it started with QO , but followed by no numbers, just letters. The fine print for types of breakers was missing. My young helper (1 1/2 years with me) had photoed the breaker label yesterday and I notieced it had dotted lines for each space as if each breaker space allowed two labels, sometimes in panels that matches twin capabilities.
When I showed my helper that my twin with the hook would not fit, I said we can't use a twin. But then I saw the installed twin sitting perfectly. (with the two snaps), I removed it and saw it was just like a regular breaker. Home Depot and Lowes only sell the 'hook type' twin and so I'd never seen this type of QO twin before. That's when I called the elec supply house. "Sure, Steve, we sell those, $60." Thought I was going to teach my young helper something but I was the one who had to learn.
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Depends on the store locations, Depot’s and Lowe’s down here sold the non-CTL at one time, haven’t checked lately.
 
Stevenfyeager said:
Where have I been for the last 20 years ? I thought QO twin or tandem breakers had the metal 'hook' like steel at the screw terminal end to keep people from trying to use them in QO panels that arent made for twins. But today, at a job, I saw a twin that did not have the metal 'hook' but instead had a snap in latch like regular QO breakers. All of the twins I have bought over the years had the steel hook. And in all the panels that did not accept twins, other electricians had broken or cut off that steel hook to get them installed (modified, contrary to code). And those twins were very loose and dangerous. But, today, to my surprise, for $60, my supply house said they sell these non-hook twins.
Does this mean all QO panels accept twins ? And all the electricians over the years that had been breaking the steel hooks off didn't have to do that ? They make a twin that simply snaps in like all regular breakers?
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Just as a point of clarification, the "CTL" and "non-CTL" mentioned by others is circuit-limiting and non-circuit-limiting.

The ones with the hooks are circuit-limiting. They can only be installed in certain panels, as mentioned.

It's the same concept as other styles like Siemens or Cutler Hammer BR, which have a rejection clip on CTL breakers to keep them from stabbing into panels without notches in the bus
 
1613228329404.pngthe non CTL is replacement for ones that once looked like this one. Those were made before the CTL requirements were in effect.
 
Stevenfyeager said:
Thanks, the model no. was no help, it started with QO , but followed by no numbers, just letters. The fine print for types of breakers was missing. My young helper (1 1/2 years with me) had photoed the breaker label yesterday and I notieced it had dotted lines for each space as if each breaker space allowed two labels, sometimes in panels that matches twin capabilities.
When I showed my helper that my twin with the hook would not fit, I said we can't use a twin. But then I saw the installed twin sitting perfectly. (with the two snaps), I removed it and saw it was just like a regular breaker. Home Depot and Lowes only sell the 'hook type' twin and so I'd never seen this type of QO twin before. That's when I called the elec supply house. "Sure, Steve, we sell those, $60." Thought I was going to teach my young helper something but I was the one who had to learn.
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Label on the cover means nothing. Square D uses same cover for more than one panel quite often. Some older covers maybe can be a clue, but the current type that has basically been around since late 80's or early 90's (basically whenever they went to the QOM style mains) hasn't really changed much in that time.

There is some covers that fit panels with less breaker spaces than the cover has, and same cover may also fit a three phase panel as long as it doesn't have a non backfeed plug on type main breaker.
 
480sparky said:
So a label that specifically lists what breakers are allowed means nothing? :oops:
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About all you are getting off the cover is that only Square D breakers are allowed. Not which type can plug in on which space.

One off top of my head is a 24 circuit cover that fits both a 20 circuit loadcenter and a 24 circuit loadcenter, and probably also a three phase loadcenter or two up to 24 circuits spaces. Some those may not be rated at all to accept tandems, especially before they eliminated the 42 circuit rule. Today they kind of gone to nearly everything accepts tandems in every space though, but still using the same covers as that part of the design hasn't really changed any.

Label on the loadcenter itself is what tells you what you can plug in and where. QO series the cover is a separate purchase item, except for some packaged for big box stores that do include a cover in the package.
 
480sparky said:
So this doesn't specify what breakers are allowed?

View attachment 2555325
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I see exactly what I mentioned - tells you only QO breakers (and Q1 which once was the 70 amp and up that physically took space on both sides of the panel) and mentions they must be CTL type, does not tell you which spaces can accept tandems and which ones can not. Some panels didn't accept any tandems at all, but the circuit directory on the door might still split each space for panels that do accept them.
 
Oh, I see. You're talking about WHICH SPACES a tandem might be allowed. I thought this thread was about whether a panel could take them AT ALL.
 
480sparky said:
Oh, I see. You're talking about WHICH SPACES a tandem might be allowed. I thought this thread was about whether a panel could take them AT ALL.
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What you posted doesn't indicate whether the panel can take tandems at all, just that if it can they must be CTL type, which is a general listing rule for all manufacturers anyway since the CTL rule came out.

some panels may have marked on the cover which spaces accept tandems, QO generally never did so as many covers also worked on cabinets that would accept more than one panelboard.

More than once I have converted a single phase QO panel to a three phase panel by simply swapping guts. Same cabinet and same cover were reused. Can't get away that easily with over 100 amp main breaker panels though, but main lug only or 100 amp or less back feed type mains it works well if the original isn't too old that it is a different design.
 
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