Split Type Breakers

In the US, some residential circuit breaker manufacturers provide a type of breaker that has two poles that will occupy a single mounting space in a load center. These are also called "Tandem Breakers". They will both connect to the same busbar, so they will have the same polarity and thus cannot be used to supply 240V, but it can effectively double the capacity of a load center in terms of 120V circuits.

Caution though: Load center manufacturers have to UL list both the load center and the tandem breakers to be used together. You cannot usually install a tandem breaker of one manufacturer into a load center of another manufacturer, even if it will physically plug in.

Hi;

I have also dealt with some issues where the panel can become extremely overloaded by the over use of these types of breakers also refered as( piggy-back) breakers. I believe some panel box label's state not to install certain breaker model #'s into to these types of panel's Depending on the usage of the proposed new circuit you also might just be better off installing a small (say 6-12) circuit Sub-Panel next to the existing distribution panel , ofcourse if space also provides as well.