Sq D as combiner box [RE-wrenches]

[sunwise at cheqnet.net]

Someone's snip....
"the Heineman breaker will not provide the AIC that
the QO needs--you must use a current limiting fuse"

Eric Smiley wrote:> 
> True. There are no current limiting breakers, so a fuse is the only
> option.

Greetings,

I've been following this discussion and I must say that I have
apparently not understood the issue to date.  Or, could it be that there
is just some confusion regarding terminology -- Current Limiting vs.
Current Interrupting.

I thought all breakers were current limiting, that is their job, to
limit the current flow on, for instance, a branch circuit.  They
typically do not have the current interrupting ratings that fuses in the
R and T class have.  A SD fuse will limit the DC current flow to/from a
given device if the amperage begins to exceed the circuits design
limits, like if someone plugged too many appliances ito a circuit with a
conductor protected by a breaker.  

They perfom poorly at current interruption, like in a battery based
system when someone sticks a screw driver into a DC branch circuit
outlet box and welds then thing in there good.  In such a situation, the
breaker would try to limit the current, but the DC rated/high current
interrupting T class fuse that is protecting the breakers would save the
day.

Could I be way off base here??? -- Kurt Nelson

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