Mark_Galeck wrote:
Hello, I was wiring something and I messed up, as soon as I turned
the heater circuit breaker (to the thing I was wiring) on, there was a
loud bang, smoke and the breaker jumped back to OFF position, that
means, it worked properly, although the part I was wiring, got
damaged. I then disconnected the damaged part.
However, now the circuit breaker appears to "short", that is, even in
the OFF position, some other wires that it controls, are hot!

Can a tripped circuit breaker, get shorted that way in the process, so
that it cannot be turned OFF, and so I should replace the circuit
breaker? Or is something else wrong?

Thank you for any insight, Mark

Mark
The bad news here is that you may need some special intervention to
protect your home from catastrophic failure of your service equipment
during some future electrical fault.

If you look at the breaker's molded plastic case you will see that it is
marked with a withstand rating. Common ratings are 5,000; 10,000;
22,000; and 45,000 symmetrical amperes. That is the amount of current
the breaker can interrupt without the case rupturing and throwing
burning plastic and molten metal around. At currents well below the
withstand the breaker can fail internally so as to no longer perform
it's function but it would fail in the off condition. It it failed in
such a way that it is still passing current then the withstand rating of
the breaker was exceeded.

Why that is important is that it shows there is enough current available
to the panel's buss bars to exceed the withstand rating of the installed
breakers. You need to have a calculation done by your utilities
engineering department, a fairly sharp master electrician, or an
electrical engineer. If the fault current available to your panels
terminals is indeed higher than the rating of the installed beakers
remedial work needs to be done to protect your home and family from the
real possibility of explosive failure of the existing breakers. The
power utility will sometimes be willing to recommend cost effective
remediation for your situation. If they are not willing to provide that
service then your best recourse is to call in a master electrician to
examine your problem.

Some examples of the kinds of things that can be done is to replace all
of the breakers with breakers recognized for use in that panel that have
a higher withstand rating. Calculation may reveal that only the main
breaker needs to be upgraded. In some installations a fused disconnect
is installed ahead of the panel to limit the fault current to the
existing breakers withstand rating. I know that this is not good news
for you but if you ignore this failure and just replace the failed
breaker then the next fault may turn one of your breakers into a hand
grenade that will not only injure the person who closes it on the fault
but also destroys adjacent breakers and spews burning plastic. Such
failures are rare in homes but they have occurred and the consequences
of such failures are quite dire.
--
Tom Horne