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Hi Larry, thanks for another perspective on the rating problem. I certainly agree that we only want to allow the amount of current to flow through the wires that the equipment load (with some margin) requires. That is exactly why I say rate for the load and not the wire - this of course assumes your wiring design selected an appropriate size/rating wire for the equipment in the first place. If my wiring selection will support my normal equipment load and I fuse/CB that line for the equipment load (which is less than the wire capability), I automatically protect the wire.
However, I've learned (well mostly) that convention,custom and natural laws are not violated without cost. Now I do like the quantum mechanics idea - just teleport to a distant location - Nahh, not as much fun - I mean how much discussion can we get into about quantum mechanics and rotary engines {:>).
Ed
SNIP.....
In summation we want to allow only the amount of
current to flow thru those little wires as we need, and no more
than that. That is what these two rules accomplish. They were
written in the National electrical code and based on physics.
And as we know the laws of physics will not be denied,
except by quantum mechanics. But we are not building
obam aircraft that require quantum mechanics,yet. HTH
Larry Mac Donald
lm4@juno.com
Rochester N.Y.
Do not achcive
Max. current for 14 Ga. wire is 20 amps and
On Fri, 20 Oct 2006 18:12:11 -0400 "Ed Anderson"
<eanderson@carolina.rr.com> writes:
One thing I have never really understood regarding fuses (or CB
for that
matter) is - why you would use a fuse/CB with the rating set to
protect the
wire!!! If you have a system operating off a power wire, it is
highly
likely that the wire will flow much more current than the system
requires by
quite a bit. So if you select a fuse or CB rating that protects the
--
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