Load shifting to fake breaker out

[iceworm]

I have a friend who was asking me if having say 200 amps per phase would trip a 200 amp main the same as loading it 195/205?

Every molded case I've seen, each pole as a separate trip element, As Big John noted, UL489 is a guiding light. Of course, I don't know if any of this applies in Oz.

For a UL489, non-100%, 200A CB in free air, 40C ambient:
Must carry 100% rated current for ever (There are some words about alternative testing at 80% in smallest enclosure)
Must trip at 135% in two hours.
At 200%, must trip in 10 seconds.

That is the short version, UL489 has 319 pages.

That says at 101% it could trip in 1 min. At 134%, could never trip. Both would be in spec.

With tolerances that sloppy, I don't think one would see a effect of a 2.5% load shift.

iceworm

 

[iceworm]

... are they cumlitive or can you trick them a bit?

Sure, one can trick them a lot. Generally illegal, and can be unsafe.

ice