Circuit breakers connected to a string of three and a transformer

Extensive use of a half breaker, double busbar or double it with a different bus terminal, it's not a  air circuit breaker  a line, which is connected to an average of one and a half circuit breaker, such as circuit breakers connected to a string of three lines and a  electric meter  , or a string of three circuit breakers connected to two lines, because a half breaker on the number of lines and the number of transformers ranging from the largest number of the transformer when the line number, there will be a string of three circuit breakers connected to two lines.