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Some wiring concerns me, advice would be nice

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Rick Law:
Hi folks, I can use some advice here:

I have to deal with the under-sink garbage disposal again.  This time I took a closer look at the wiring as I am considering lengthening the cable so I can do things easier in that under-sink cabinet easier next time.  I am seeing two things that I am not comfortable with.

The original cable that connects to the main is connected via the dish-washer.  So, two appliances are on the same set of wire nuts to the 20 Amp main.

I can't see any print on the outside jacket for the 20Amp main's cable or the garbage disposal's cable. They are both solid core.  I assume the 20Amp cable from the wall is 12 AWG.  The 20Amp main's core is visibly bigger than the garbage disposal's cable's core - which of course implies the 1/2 hp garbage disposal unit has a thinner AWG.  The dishwasher's cable is factory and is 16 AWG also twisted onto the same wire nut.  So the garbage disposal is wire nut connected to the main inside the dishwasher's junction box.  This is the first thing I am uncomfortable with.  3 wires (washer, disposal and main) in each nut inside the dish washer's junction box.

I am considering lengthening the garbage disposal's cable (to on/off switch of the disposal) from about 3 feet to 5 feet so it can follow the contour of the cabinet under the sink.  From on-off switch to disposal is about another 2 feet of cable.  Connecting the garbage disposal's thinner than 12AWG to the 20Amp main is the second thing I am uncomfortable with.  The factory dishwasher cable (16 AWG stranded) is factory, so that is that.  But the garbage disposal's wire is not factory and is thinner than 12 AWG.  If the disposal has a short, that 3 feet (or 5 feet) of thinner-than-12AWG could be carrying 20AMP till the main's circuit breaker breaks.

Am I too overly concern here with the two things I am uncomfortable with?  After all, it has been that way for > 20 years...

Your view/advice?  Thanks.

WattsThat:
Yup, you’re overly concerned. It’s the way virtually every appliance is wired.

Back up a step to understand why what you have is perfectly okay. The 20 amp breaker is there to protect the wire that is attached to it, nothing more, nothing less. It’s not there to protect the wire inside the appliance. It’s the gauge and the length of the wire is what matters. In the US, a 20 amp branch circuit requires protection at 20 amps, 14 gauge, 15 amps, so you’re good to go there.

There is another circuit breaker in the disposal that is thermally rated for the motor power. The wire inside the appliance can withstand that secondary breakers current rating. It’s that little red button on the bottom of the unit.

I honestly can’t quite figure out how things are wired. These days, disposals are wired with a standard 3 wire cord set plugged into a switched outlet. If yours is hard wired, did the electrician use the disposal as a junction box, that is unswitched power enters the unit and the switch is connected inside the junction box of the disposal? There usually isn’t enough room in them to do that.

tautech:

--- Quote from: Rick Law on September 27, 2020, 10:44:24 pm ---Your view/advice?  Thanks.

--- End quote ---
You said:

--- Quote ---1/2 hp garbage disposal unit
--- End quote ---
Some 400W current draw.......do the maths.  ;)

Teledog:
Not that it's terribly "kosher", but after replacing the range vent hood for the umpteenth time, I put in shielded 14/2 to a metal outlet box in the cabinet above the range hood.
Now I merely have to "plug in" the latest cr*p replacement.
I will do the same for the next next 3 year replacement of the "well manufactured eco-green-disposable" sh*t-washer.    >:D
G'luck! :-+

floobydust:
Electrical code ultimately wants a branch circuit and everything connected to it good for the same current. But 15A is close to 20A and the extra 5A would not burn down the house.
Garburators frequently get a locked rotor due to utensils getting dropped in there, so they all have thermal circuit-breakers to protect the motor. It's the red button on the end.
A dishwasher really doesn't draw much current unless the heater is on.

I would not worry beyond using BX for the hop from JB to the garbage disposal. NMD is not right.

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