"Ignoramus5533" wrote in message
...
I came into possession of a few used 400-600A circuit breakers. Each
is the size of a milk jug. While researching prices on them and such
(they sell for $150-200 on ebay), I learned that some cost many
thousands of dollars new. I saw numbers from $2,500 and higher.

I am curious just what makes them so expensive. Do they have any
precious materials inside? Or what?


You don't mention a lot of details, but in addition to all the other
comments, I would add that you have to remember not all 600A breakers are
the same.

The phase-phase voltage can be different, and more importantly, the
interrupting rating. Depending on the service, it may have to be able to
interrupt short circuit currents in the 10kA range, or as high as 500kA.
Some old units used to have sand-fuses built into them. The breaker would
open for modest faults, but if the fault current was *really* high, the
breaker would just arc/weld until the sand fuses blew. They had a much
higher interrupt rating.

Point is, once you get larger than the average residential service panel,
there is more to a breaker than just the full-load current rating. Inverse
time tripping curves, Very Inverse times, high interruption ratings, even
whether it's meant for AC or DC.

daestrom