Frame Rating

[mikehughes8]

Can someone please explain to me what the frame rating of a circuit breaker refers to. I think it has something to do with the maximum trip settings on the breaker but I'm just not sure. Also, a 600A panel means what? The panel structure is rated to handle 600amps of ground fualt current? Or does this mean its built to hold a 600A breaker? I appreciate the help in advance.

 

[tlaidman]

circuit breakers with adjustableand replacable trip units have a frame size to indicate the largest trip unit that can be used in that frame.

 

[LarryFine]

In other words, the frame is a physical property, not an electrical one. You know how the small cartridge fuses go up to 30a, the next size to 60a, then 100a, etc?

This is the same thing for breakers. The frame size is the largest rating that comes in that case size. The typical 1" breakers usually top out at 100a, although I have a few 125a 2-pole breakers.

 

[templdl]

A 600a frame breaker is a specific size for a given manufacturer and has the capablility to be rated up to 600a. Often times a 600a is specified with a 400a trip unit which can be refitted with a 500 or 600a trip nit at a later date.
If one use a 400a frame with a 400a trip it will work just fone and will alos save on cost. However, one now is limited to a 400a frame.