#### uwochris

##### Flightinfo's sexiest user

- Joined
- Dec 21, 2001

- Posts
- 381

- Total Time
- 2500+

I understand that circuit breakers provide a form of protection against excessive current. Looking at electrical system diagrams of various a/c, I see that the circuit breakers have many different amp limits (i.e. 5 amp CB, 10 am CB, etc).

This may seem like a dumb question, but what is the significance of the amperage of the CB itself? For example, here is an exert from a Metro book:

"

*The pilot trim motor is supplied 28 volts DC through a 10 amp CB from the left essential bus."*

I just don't understand what the significance of that "10 amps" is. Does it mean the CB will pop once it is 10 amps over the prescribed limit? Also, how do they choose what amperage of CB to use (in the above example, would a 5 amp CB do the same job?)

Thanks in advance,

Chris.