"Ralph Mowery" wrote in message
m...

"Robert Green" wrote in message
...
That's what motivated me to change. If the fridge kicked off when the
toaster oven was on, the breaker would trip, and that was even with a
20A
breaker on a 15A circuit. The typical breaker can't tell what's
downstream
and whether it's drawing more current than the *wire* can handle. It
only
"cares" whether there's more current flowing out of the breaker than the
*breaker* can handle.

As I mentioned before, you do not size the breaker for what is downstream,
you size it for the wire. If you need to have a certain amount of current
for several devices, you use large wire and a breaker to match.

I don't think I said otherwise. What I said was in relation to finding an
breaker too large for the circuit. It could easily allow enough current to
pass to cause a fire. That's what I found. Someone had put 20A breakers
that seemed pretty clear too large for the size wire they were connected to.
In that case, a 19.5A load wouldn't trip the breaker but would warm up the
in-wall wires pretty well, perhaps melting the insulation and causing an
arc. IIRC, that's why arc-fault breakers came into being. (-:

IMHO, to be completely sure, you need to inspect the panel to make sure that
all the wires pulled are of the same era if you want to use sizing as your
only guide. Even then, every obvious new addition to the panel is suspect,
especially if there aren't any matching inspection stickers. There's also
no way to tell whether some home electrician added four 150 watt floods to a
front door sconce circuit and has severely overloaded the circuit way
downstream of the wire at the panel. The older the house, the more likely
circuits have been tapped. That's why I mentioned investigating to see
which breakers were original to the panel. Tapped and overloaded outside
circuits might be fine in the cold weather and heat to the point of failure
at the peak of summer.

Ralph, let me ask you what would you think if you found an older panel (50
years old) with cloth covered wire that all looked to be about the same age
and gauge. They're hooked up to a mix of half 20A and 15A breakers with the
20A breakers being obviously much newer than any of the 15A breakers. The
20A breakers were all made 10 years after the panel. The 15A breakers have
the same manufacture date (almost) as the panel itself. (I'm excluded some
of the newer circuits that were obvious late-comers like central A and
grounded outlets near windows for window A/C's for the sake of simplicity.)

Older houses were wired when the kitchen did not have many high current
devices in use. Now many people have the several things going at once.
Toaster, microwave, coffee pot. About 30 years ago I lived in a 2 bedroom
apartment that was built in the 1950s or before. It had 2 20 amp fuses in
it for the whole thing except the stove.

Wow. Ironically, we may see a time when devices become so efficient that
you can live on 40A all over again.

It's interesting how the patterns of electrical usage have changed.
Nowadays, since everything has a charger or line cord you can almost never
have enough outlets. I don't think I know a single person who doesn't use
multiple outlet strips throughout the house. In the modern kitchen, even
three 20 amp circuits might not be enough for some households.

--
Bobby G.