How many CBs permitted?

[greeny]

If a 20 slot panel is full and no maximum number of CBs can be found on the panel cover, can you install tandems? How many? Common sense?

 

[charlie b]

Ask the manufacturer, or read their documentation. It's up to them. It's all a matter of whether the panel is listed for tandem breakers.

 

[RICK NAPIER]

Some panels didn't identify the number of breakers that were allowed but would identify the type of breakers allowed in that panel. In this way you could tell if mini's were allowed.

 

[mxslick]

And some panels restrict the actual location that tandems can be placed in, by use of exclusion features on the bus and/or breakers.

The panel label (if present and readable) will show location and max numbers of tandems allowed.

 

[Volta]

And some panels restrict the actual location that tandems can be placed in, by use of exclusion features on the bus and/or breakers.

Circuit Total Limiting (CTL) panel / breaker combinations probably came in after 1965.

A lighting and appliance branch circuit 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 approved.

The panel label (if present and readable) will show location and max numbers of tandems allowed.

And in addition to the 'label denoting specifications' for the panel, we can often at least find a hint in the original 'label for breaker purposes' directory, either with 'a' or 'b' on some numbered lines, and/or dashed lines to imply dual labels in one space.

 

[HotConductor]

My Square D rep. told me that Square D QO breakers are rated for two conductors under one screw.

Is that correct?

 

[Volta]

My Square D rep. told me that Square D QO breakers are rated for two conductors under one screw.

Is that correct?

Of course the general rule is no- 110.14(A), but the rep. is right, for the Equipment Grounding Conductors, usually, with some restrictions about sizes. But not for Grounded Conductors.
Some breakers, sometimes . . .
They do make some 'sub-feed' lugs that allow two grounded conductors in the main lugs.

 

[iamintn]

My Square D rep. told me that Square D QO breakers are rated for two conductors under one screw.

Is that correct?

I am having a hard time understanding what this has to do with the original question, but the quick answer is yes depending on the wire size, wire type, and breaker rating. 10A-30A is rated for (2) #14-#10 CU. Reference page 2 on the link below for more information.

http://static.schneider-electric.us/assets/digest/load-centers.pdf

 

[jaylectricity]

My Square D rep. told me that Square D QO breakers are rated for two conductors under one screw.

Is that correct?

I am having a hard time understanding what this has to do with the original question, but the quick answer is yes depending on the wire size, wire type, and breaker rating. 10A-30A is rated for (2) #14-#10 CU. Reference page 2 on the link below for more information.

http://static.schneider-electric.us/assets/digest/load-centers.pdf

If you look at the actual breakers, you will notice that each terminal plate has a place for a conductor on each side of the terminal screw. So yes, you can put two conductors in there, provided you put them each in their own place.

And yes, what does this have to do with anything?