Tandem breakers don't fit in CH panel?

[BackAgain]

I have a 100 amp Cuttler Hammer subpanel in my shop. It's just about full, so I wanted to move some of the lighting circuits to 20A tandem breakers. I bought a brand new 30A single and 20A tandem breaker like these:
http://www.homedepot.com/Electrical...splay?langId=-1&storeId=10051&catalogId=10053
http://www.homedepot.com/Electrical...splay?langId=-1&storeId=10051&catalogId=10053

Both say "type BR". Both look identical EXCEPT the contact in the back where it attaches to the panel. The tandem breaker has an extra peice of metal in the hole, which prevents it from being installed into my particular my panel.

But I don't understand why?! All the other panels I've seen take tandem breakers just fine. In fact a Siemens tandem breaker fits fine in my panel. Why does the CH brand tandem breaker not work? They seem to intentionally prevent it from being installed in my panel...

 

[mrb]

look at the label on the panel. your panel may not be able to accept tandems. the siemens tandem that fits is probably a non class ctl type. If your panel is for example a 20/20 it cant take tandems, if it is a 20/30 it would have ten slots which could take a tandem.

 

[Norcal]

No notch in the bus stab means it is not designed to accept a twin breaker, this has been the case w/ panels built since 1968 (Look on the UL label for "CTL panelboard"),the wiring diagram for the panel which will be on the door of newer panels & in the box of older ones, it will show which spaces are allowed to accept twins, also as written by poster mrb the catalog number will also state the same thing.

 

[Falcon67]

Make sure also that you are placing the breaker in the right spot - my panel (GE, not CH) forces the tandems into slots that allow them to pick up each buss. Makes for a bit of odd stacking in the panel and little "tic-tac-toe" breaker arranging.

 

[oleguy]

cutler-hammer makes one to fit.part # will say br&A &PNDL.DOES NOT HAVE THE METAL CLIP FOR NOTCHED BUSS.IT IS JUST LIKE A REGULAR PANEL.

 

[Norcal]

cutler-hammer makes one to fit.part # will say br&A &PNDL.DOES NOT HAVE THE METAL CLIP FOR NOTCHED BUSS.IT IS JUST LIKE A REGULAR PANEL.

But it is a violation of the UL listing to use it, and contrary to the NEC to use them in a panel built after 1968, those breakers state they are not for a CTL assembly......

 

[Norcal]

Make sure also that you are placing the breaker in the right spot - my panel (GE, not CH) forces the tandems into slots that allow them to pick up each buss. Makes for a bit of odd stacking in the panel and little "tic-tac-toe" breaker arranging.

General Electric has a peculiar way for the method their twin breakers mount/connect into a panel, GE twins only fit GE panels & no others fit w/o being a hack electrician/DIYer.

 

[oleguy]

But it is a violation of the UL listing to use it, and contrary to the NEC to use them in a panel built after 1968, those breakers state they are not for a CTL assembly......[/QUOT

that is right.my bad.thought it was 1965.still can't use them anyway.it just keeps from over loading panel rating.

 

[BackAgain]

Hmmm....well, it does fit on the left side of the box. I don't understand why they artificially limit the number of breakers though?? Even if I doubled them all I could only fit 36 circuits....

No matter how hard I try I can't find anything on it about how many circuits it's supposed to hold, I see "UL Listed CTL Panel Board" and a sticker inside with some info on it, and it says "see door for more info". The door has a wiring diagram but again doesn't say how many breakers and then says "check in the box for more info".

 

[Charles (in GA)]

Hmmm....well, it does fit on the left side of the box. I don't understand why they artificially limit the number of breakers though?? Even if I doubled them all I could only fit 36 circuits....

Lots of issues in the UL certification of a box, panelboard, etc. One would be the number of wires vs the volume of the box, heat generated by the breakers (yes, even when operating normally they generate some small amount of heat, which adds up), issues like this serve to limit the number of circuits in a given size panel.

Charles