Siemens twin breakers, CTL vs NONCTL?

[kwired]

The door diagram usually indicates which one hold tandem or half size breakers.

Not always true with newer Square D. One cover fits more then one panel. The label inside the cabinet will be correct for whatever interior was factory installed.

I have swapped guts on say a 30 circuit single phase to convert to three phase - they were in same can. But the label inside still was the one for the single phase guts.

 

[OBi]

If you have a Square D Homeline panel, Square D has ever produced a Non-CTL breaker for that panel. You will need to find the circuits that have the notch in the bussing that accepts the CTL breakers.

The Square D QO breakers do have Non-CTL breakers available.

All manufacturers are still making loadcenters that have some spaces made for twins and some not. It is a marketing strategy. They discount the CTL twins heavily for new construction. The Non-CTL are priced higher for use in existing panels.

The only manufacturer that I have ever run across that did not have some form of rejection feature for twins was the old Zinsco panels. Even the much maligned FPE had a rejection feature for their "wafer" breakers.

 

[brantmacga]

If you have a Square D Homeline panel, Square D has ever produced a Non-CTL breaker for that panel...

I’ve heard the plastic above the jaw on a homeline tandem breaker is especially soft; one tap of a flathead chips it out.



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[jaggedben]

So this bite me in the butt today.

Installing a two pole circuit in a full SQD panel. New house, new panel, installing two tandems to make room. Assumed they had gotten over the CTL/non-CTL thing on new panels especially since there were already three tandems in the panel. I start popping out breakers to combine them and my CTL tandems won't fit. I pull out the top six breakers looking for the CTL tandem allowed spaces and they don't fit. I look at the tandems already installed in the panel and they are CTLs that have been illegally modified.

I put everything back together and tell the HO I need to order some "special" (non-CTL) breakers to make this work. Upon doing some research to order said breakers I find that the CTL allowed spaces are at the BOTTOM of the panel! What The! Why didn't I check the bottom. I've just always seen the tandems at the top. Duh!

That was a homeline panel, wasn't it? You know if you looked a the diagram in the panel label it would likely have indicated that. I'll give you ghe benefit of the doubt and figure the label was missing.

 

[norcal]

Could someone help me find the Code article that would permit installing a tandem breaker in an existing 30 circuit panel that is listed fo 30 circuits, but I need just one more circuit?

Listing and labeling of the panel which we are required to follow, could do as someone did to a Siemens panel I came across, just use a hacksaw to make your own notch, but is wrong in many ways.

If you have a Square D Homeline panel, Square D has ever produced a Non-CTL breaker for that panel. You will need to find the circuits that have the notch in the bussing that accepts the CTL breakers.

Homeline panels were introduced many years after CTL standards came out so no reason to have them & to my knowledge SQ D has not had them classified by UL to be used in competitive makes.

 

[RICK NAPIER]

I beleive this section has been in the NEC since 1965 requiring CTL breakers the non CTL breakers are for the panels that allowed these breakers for ten years before 1965. Eaton has a series of panels that allow non CTL breakers since every space is designed for two circuits.
408.54 Maximum Number of Overcurrent Devices. A
panelboard shall be provided with physical means to prevent
the installation of more overcurrent devices than that number
for which the panelboard was designed, rated, and listed.