Twin/Tandem Breakers

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
For SQ D you will need to find a "QO tandem" not a "QOT" click HERE

I'm not sure about the Siemens.

Roger
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
If you mean they can be installed anywhere in the panel then wouldn't the listing be violated? I don't believe Siemens has one
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Some tandems have a built-in physical rejection method so they'll only fit in specific slots. The non-CTL versions are usually much more expensive.



What is the difference between CTL and non-CTL breakers?


CTL stands for circuit total limitation. This normally is applied to the "twin" or 2 in 1 breakers used in residential loadcenters. CTL breakers have a rejection feature on the bus connection side of the breaker. This prevents them from being used in certain areas of a loadcenter. Non-CTL breakers do not have this rejection feature and will fit in any space in the loadcenter.
 

kwired

Electron manager
Location
NE Nebraska
I use tandem breakers all the time, and I have no idea what the question is.
If you have no idea you likely have been using NON-CTL versions that have no rejection features and your tandems always fit in any slot you use.

CTL versions have rejection features and if panel wasn't intended to accept a CTL breaker in a particular slot it will not plug in there unless you defeat the rejection feature somehow.
 

tom baker

First Chief Moderator
Staff member
One way to tell if the panel will accept ctl breakers on sq d, is the panel sch on the door. If it has a dotted or thin line in the middle of the block, it will accept ctl breakers. And sometimes the panel number is an indication, ie 10-20 means 10 reg or 10 ctl. I agree there are many non ctl btrakers used where not allowed
 

MAC702

Senior Member
Location
Clark County, NV
Oh! Actually, I use the CTL versions, I just had no idea what he meant by "hook" as I was picturing something else and my brain wouldn't reset to think of other possibilities. Thanks.
 

kwired

Electron manager
Location
NE Nebraska
One way to tell if the panel will accept ctl breakers on sq d, is the panel sch on the door. If it has a dotted or thin line in the middle of the block, it will accept ctl breakers. And sometimes the panel number is an indication, ie 10-20 means 10 reg or 10 ctl. I agree there are many non ctl btrakers used where not allowed
At one time yes. Eventually it got to where one cover sometimes worked on more than one loadcenter, and still is that way today. You can get a 20 circuit loadcenter that is using same cabinet and cover as a 24 circuit version, and even within those parameters one may be rated for tandems in every space, limited number of spaces, or not rated for any tandems at all.

Since they took out the 42 circuit rules, you are seeing more panels that are rated for tandems in every space. But with the need for AFCI's in most things in a dwelling you still are not seeing a panel on new installs that is full of tandem breakers.

This really was a big deal for mobile and manufactured homes at one time, less space and maybe even less weight were big factors in decision to use tandems and quad breakers for those applications, AFCI's took that away at least to some extent.
 
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