Some wiring concerns me, advice would be nice

[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]

Your view/advice?  Thanks.

You said:

1/2 hp garbage disposal unit

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.   
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.

[andy3055]

To simplify, if I was planning to sort this, this is the way I would go about it.

1.  Make sure the outlets under the sink are wired in a way that makes sure that one is switched.
2.  Renew the garbage disposal wiring with a 3 wire cord that is rated for the current required-see the specs printed on it. Plug it to the switched
     outlet.
3.  If required, renew the 3 wire cable on the dishwasher and plug it direct to the un-switched outlet as it does not require an external switch.

     This way, everything is separate and does not need fiddling unnecessary wiring to fix one or the other. I prefer flexible cord.

[tkamiya]

In some states, code requires garbage disposer and dish washer not share circuit with anything else.  In other states, they don't care.

The circuit breaker is 20 Amp.  Wire coming out of your wall is 12 gauge, correct?  If it goes into a junction box, and whatever wire comes out of appliances are connected to it directly with wire nuts correct?  And they are all in a junction box that happens to be under dish washer?  That's alright.  There is no problems there.  Most common way for garbage collector is to use 14 gauge wire and put it in armored sleeves.  Naked Romex are not approved for use in where house hold members can easily reach and possibly cause damage.

If your house was built in that way, I'd not be too concerned. 

[Rick Law]

...
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.

Actually, the other way around - the disposal uses the dish-washer as the junction box.  Three wire nuts (green, white and black wire), each nuts has 3 wires twisted together (main power in, power out to disposal, and power for dish washer).

I think my concern is influenced by my disliked that connection - and is looking for a reason to redo it.  There is very little slack with that power cable to the disposal.   Just to pull the dishwasher out a couple of inches to replace the water hose washer... I had to "un-nut" everything, remove both the main and disposal-power cables from the junction box on the dish washer, replace the water host washer, and reconnect the power cables after the dishwasher is pushed back in.  When it is in, there is very little maneuvering space so reconnecting is difficult.

The factory stranded 16 AWG power wire has strands soldered together.  Soldering makes the exposed part very stiff and difficult to twist around the other two wires.  I very much dislike that.  It is always a struggle when I have to reconnect them. 

In some states, code requires garbage disposer and dish washer not share circuit with anything else.  In other states, they don't care.

The circuit breaker is 20 Amp.  Wire coming out of your wall is 12 gauge, correct?  If it goes into a junction box, and whatever wire comes out of appliances are connected to it directly with wire nuts correct?  And they are all in a junction box that happens to be under dish washer?  That's alright.  There is no problems there.  Most common way for garbage collector is to use 14 gauge wire and put it in armored sleeves.  Naked Romex are not approved for use in where house hold members can easily reach and possibly cause damage.

If your house was built in that way, I'd not be too concerned. 

The 20 Amp was as the house was built so I assumed it was AWG 12.  The garbage disposal was added on.  It is naked romex but hidden inside the under-sink cabinet.  It seems so much thinner than the 20 Amp it may be AWG 16 instead of 14.

I have some concern about it being naked too.  Besides the nest of water pipes in there, some cleaners are kept in that cabinet.  So in theory, I could accidentally burn/cut the wire if I am torch-soldering on a new tap carelessly.

re:"In some states, code requires garbage disposer and dish washer not share circuit with anything else.  In other states, they don't care."

Those connections were done more than 20 years ago.  I know as recent as 2014, dish washer and disposal on the same circuit was fine (when combined load is less than 20 Amp).  But 2014 is a long time ago...

And then there is local (township) rules...  I very much dislike big-brother rules, and they get more intrusive every time they change it.  My water heater was replaced recently.  After the heater was replaced, the plumber doing the work told me: "new regulation, you have to get the township to come inspect it and get it certified."  They didn't require that when the last water-heater was replaced.  It was just as the State-wide virus full lock down started.  I can't get anybody to even answer the phone...  I do wonder if they are just doing it for the certification fees...

[tkamiya]

I've never heard of AWG 16 Romex.  You are probably looking at #14.  There should be some marking on the wire.  If it is stranded, it's not Romex.  Typically, internal wiring is like you say, thinner wire.  When electricians bring them out, they'd use #14 and ruggetize it.  Those soldered wires make it easy to use wire nuts.  I actually like them.

You are welcome to put a junction box where house #12 wire comes out, then branch it to dish washer and garbage disposer.  I really recommend ruggetizing connections, since under the cabinet is easily accessible. 

Typically speaking, minor repair or replacement of existing minor appliances do not require inspection.  Major renovation like replacement of A/C does require inspection.  Water heater?  In my area, it's considered minor repair.  What you call big brother rules....  they exist for a reason.  Yes, some rules are silly, but most are from years of seeing damages and deaths.  It makes sense to follow them to best of your ability.

All in all though, you are probably worried about nothing.  It'll be fine like that.  I've seen a lot of scary looking thing in my attic.  Some I fixed, some I left it alone, depending on actual risk.  By the way, I do have an electrician's license from Japan, but it's not valid in US. 

[james_s]

It's not uncommon for a garbage disposal or even the dishwasher as well to have been retrofitted into an older house. The most important thing here is that all of the connections are securely made, using the proper type of wire and protected in appropriate junction boxes that are grounded if they are metal. Without seeing pictures it's very difficult to picture exactly what you are dealing with here but if it were my house I would probably tidy it up a bit. Install a junction box where the wire comes out of the wall to feed the appliances. Open two knockouts in that and run one wire to the dishwasher and a second wire off to the switch that controls the garbage disposal. Since it's a 20A circuit you should use #12 wire for all of this, romex is fine where it is protected, or use metallic flex (AC). My house has separate circuits for the dishwasher and disposal and the disposal is hardwired metallic flex as is typical of houses in this region built in the era when mine was but when retrofitting a disposal into an older house it is very common to tap it off of the dishwasher circuit. Honestly I don't know why code requires a dedicated circuit for the disposal, most are 1/2 HP or less and run for maybe 30 seconds a day if that. If you were cooking for an army and running the disposal for hours at a time then a dedicated circuit would make sense but that's certainly not typical. Whenever I brush up on the NEC prior to doing some permitted work I'm always scratching my head about some of the requirements.