In article ,
Wayne Whitney wrote:

On 2008-08-26, Kevin Ricks wrote:

Whats the electrical difference between a double pole breaker and 2
breakers with the handles tied together?

The difference is that in a 2 pole breaker, the trip mechanisms are
tied together internally and will both trip if the unit sense an
overcurrent. For two single breakers with a handle tie, this is not
reliably true.

Wayne

Curious minds want to know why tying the trip mechanisms together
internally is intrinsically safer or more reliable than tying them
together externally.