Enclosed Breaker

[mstrlucky74]

If an enclosed circuit breaker say 225AT/400AF. What?s theactual size of the breaker? I know the AT and AF is fuse and trip. Thanks.

 

[augie47]

The size will vary depending on manufacturer and the actual frame size which is often governed to a degree by the AIC rating. No "standard" answer.

 

[jim dungar]

If an enclosed circuit breaker say 225AT/400AF. What?s theactual size of the breaker? I know the AT and AF is fuse and trip. Thanks.

The most common interpretations seem to be:
AF = Amps, frame - the maximum ampere rating available in that particular physical construction
AT = Amps, trip - the nominal Long time setting of the protective device.
and an uncommon, but no less important, one
AS = Amps, sensor - the maximum range of the internal current sensing mechanism.

Your example is a 400A size device with a 225A full load rating.

Another example is:
A Square D breaker part number LGL36070xxxx is the physical size of 600A breaker (AF), but its internal current sensing guts are only 250A maximum (AS), and with an adjustable trip range dialed down to 70A(AT)

 

[mstrlucky74]

Ty