Class CTL Circuit Breakers


I have a Siemens panel that in the past had a twin 20amp breaker installed (ie. two 20 amp circuits in one space).
Needing to free-up another space, I bought a model QT Q2020 twin breaker.
But -- I couldn't get it to seat in the panel.
Further investigating revealed that the new twin breaker is a "Class CTL" and the old twin was not.
Questions Can I get and install a non-Class CTL twin breaker like the one that was already there?
Is it safe?
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On Sun, 19 Nov 2006 17:33:24 -0500, "The Streets"

closely at the label on the panel and see if there are some CTL compliant slots. You can usually swap breakers around to get to them.
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Yes - the old breaker that works is marked "for replacement only".
I've checked the label but I don't see any mention of any slots being different. In fact, I didn't see the letters "CTL" anywhere on the label (though some of the print is quite small).
We bought this house new in early 2001. It was under construction in 2000, but I don't know exactly how old the panel might be. I read that "Class CTL" came into existence in 2000.
I'm guessing that my panel doesn't have any CTL compliant slots. If that's the case, any harm in installing another non-CTL twin?
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The Streets wrote:

Look for a UL sticker. If the panelboard is a CTL the UL sticker will say "class CTL".

If the panel is non-CTL you can install another non-CTL breaker.
Usually a CTL panelboard will use the lower one third or so of the busbars in the panel for CTL breakers. For example, a 30/40 panelboard will have 30 regular spaces available, with the lower 10 spaces used for CTL tandum breakers. If the panel is indeed Class CTL and you have to swap breakers around to get to them, if any two circuits are sharing a neutral, be sure that those two circuits get landed on opposite legs to prevent the neutral from being overloaded.
The idea is that the panelboard should have only the number of breakers for which it is designed. In the example of a 30/40 the max would be 40. No one panelboard is permitted to have more that 42 breakers due to possible overheating and/or nuisance tripping.
Also, you may be able to find two or more general purpose circuits that are not heavily loaded, splice them together under a wire nut with a pigtail to one breaker. That would free up one breaker anyway.
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wrote:

OK -- Thanks!
I checked the UL label and there it was -- "Class CTL". So I have a CTL panelboard. But the slots I've been working with so far (last 4 on the bottom left) all seem to have a large "stab" that won't fit in my CTL twin breaker.
So the CTL slots must be somewhere else in the panelboard -- right??
I'd rather not keep pulling breakers until I find them -- is there a better way (Googling my model number and other avenues have not been helpful)?
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