On Tuesday, December 10, 2013 4:35:29 PM UTC-5, firstname.lastname@example.org wrote:
"How does the overload protection protect the wiring?"
I replied with:
"The overload protection in this case is inside the motor
And when you didn't understand that, I told stated:
"The overload protection is in the motor. That protects the motor and the *wiring* from overload, because the motor is the load."
Since you're having trouble, I'll try to explain it at your
level. If the load, ie the motor seizes up, starts to burn
up, etc and it results in an overload, the overload protection
in the motor cuts it off. There is no other load, you can't
plug in more motors, more lights to "overload" the wiring. Therefore
that protection in the motor protects the motor and the wires
serving it from overload. Words have meaning you know...
If that is beyond your comprehension level, that's OK.
The folks that write the NEC understand it, cover it, set
the rules for conductor sizing for it, as GFRE also
tried to explain to you.
So, your incredulity once again shows that you don't know what
you're talking about when it comes to even practical application
On Tue, 10 Dec 2013 15:37:52 -0800 (PST), " email@example.com"
That is correct. There are 2 issues here.
Overload protection is all about the current the motor draws. That is
internal in the motor or in the motor starter if you have one.
The branch circuit over current protection (panel breaker) is there to
handle faults in the wiring and that can be at a significantly higher
rating than you have in a general use circuit where there is no
supplemental overload protection.
The article people seem to know the best is 240.4(D) that has the good
old 14ga a and 12ga - 20a is actually a modification to the general
rules for "small conductors". It used to just be a foot note to table
310.16, the basic ampacity tables.
This was added because these small conductors are most likely to be on
circuits with receptacles where the end user gets to select the load.
You only have to look at holiday decorations to see that in action.
People keep plugging in lights until the breaker trips and they unplug
a string or two.
240.4(D) enforces that good old 80% safety factor we want by limiting
the breaker to 80% of what the wire is actually good for.
240.4(D) does have the disclaimer "unless otherwise permitted in the
code" and some of those permissions are in the dedicated motor
circuits, HVAC condensers and welders.
My possibly not-to-code answer. Unless you plan to run the disposal
for long periods of time, like 10 or more minutes at a time, I
personally would not worry about it and just add the circuit. The
only time the load would be particularly high would be if you happened
to run the dishwasher and disposal at the same time and as I said,
unless you are planning on marathon disposal sessions you just won't
be loading the circuit long enough to be an issue.
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