Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

How To Wire Dishwasher and Garbage Disposal on Same Circuit

1,059 views
Skip to first unread message

Edge

unread,
Dec 8, 2013, 12:42:47 PM12/8/13
to
At this home there is a 20 amp breaker in the electrical panel that is pencil labeled as for the dishwasher and garbage disposal. At the junction box on the kitchen wall near the sink we see the 12 gauge wire feeds from the panel. Three 14 gauge wires, hot-black/neutral-white/ground-green, are routed from this box to another junction box underneath the sink through conduit. A whip from the dishwasher is hardwired to the wires under the sink.

We want to add a GE half horsepower garbage disposal that is suppose to draw only 4.5 amps. Can we just pull another hot 14 gauge wire for the garbage disposal and use the existing white neurtal already there for the dishwasher? Does it matter whether 14 gauge is used rather than 12 gauge wires for either device?

Daring Dufas : Hypocrite TeaBillie on welfare

unread,
Dec 8, 2013, 1:00:42 PM12/8/13
to
Sure. Burn down your house.

There is a reason electricians leave them on separate circuits.

Fucking moron.

Message has been deleted

Oren

unread,
Dec 8, 2013, 1:01:57 PM12/8/13
to
On Sun, 8 Dec 2013 09:42:47 -0800 (PST), Edge <wmoy...@comcast.net>
wrote:

>At this home there is a 20 amp breaker in the electrical panel that is pencil labeled as for the dishwasher and garbage disposal. At the junction box on the kitchen wall near the sink we see the 12 gauge wire feeds from the panel. Three 14 gauge wires, hot-black/neutral-white/ground-green, are routed from this box to another junction box underneath the sink through conduit. A whip from the dishwasher is hardwired to the wires under the sink.
>
>We want to add a GE half horsepower garbage disposal that is suppose to draw only 4.5 amps. Can we just pull another hot 14 gauge wire for the garbage disposal and use the existing white neurtal already there for the dishwasher? Does it matter whether 14 gauge is used rather than 12 gauge wires for either device?

" Fully explained dishwasher disposal wiring diagrams with pictures
for wiring the outlet that serves a dishwasher and a garbage
disposal."

URL:

<http://www.ask-the-electrician.com/disposal-wiring-diagram.html>

Oren

unread,
Dec 8, 2013, 3:13:04 PM12/8/13
to
On Sun, 8 Dec 2013 09:42:47 -0800 (PST), Edge <wmoy...@comcast.net>
wrote:

>We want to add a GE half horsepower garbage disposal

Edge,

BTW, if this a first GD install, take note in the instructions about
an air-gap vent pipe and _the removal_ of the plug from the GD.

Dirty DW water can back up into the sink, iirc.

... just a note
Message has been deleted

The Daring Dufas

unread,
Dec 8, 2013, 3:45:44 PM12/8/13
to
On 12/8/2013 12:00 PM, Daring Dufas : A Sock Of Killer Loon wrote:
> Sure. Burn down your house.
>

Killer Loon, living proof that human females should never have sex with
farm animals. ^_^

TDD

mike

unread,
Dec 8, 2013, 4:15:09 PM12/8/13
to
On 12/8/2013 10:01 AM, gfre...@aol.com wrote:
> On Sun, 8 Dec 2013 09:42:47 -0800 (PST), Edge <wmoy...@comcast.net>
> wrote:
>
> All the wires should usually be #12 BUT if you are serving a pure
> motor load like the disposal, you could use #14.

I'd consult the building inspector who is gonna approve it on that.
He may frown on using less than #12 on a 20A breaker.


(125% of FLA) Not so
> with the dish washer since it is not a pure motor load.
> Whether they can share the circuit would depend on the nameplate
> rating of the dishwasher.
> Take 125% of the largest load and 100% of the other one. It has to be
> 20 or less.
>

k...@attt.bizz

unread,
Dec 8, 2013, 4:35:48 PM12/8/13
to
On Sun, 08 Dec 2013 13:01:43 -0500, gfre...@aol.com wrote:

>On Sun, 8 Dec 2013 09:42:47 -0800 (PST), Edge <wmoy...@comcast.net>
>wrote:
>
>>At this home there is a 20 amp breaker in the electrical panel that is pencil labeled as for the dishwasher and garbage disposal. At the junction box on the kitchen wall near the sink we see the 12 gauge wire feeds from the panel. Three 14 gauge wires, hot-black/neutral-white/ground-green, are routed from this box to another junction box underneath the sink through conduit. A whip from the dishwasher is hardwired to the wires under the sink.
>>
>>We want to add a GE half horsepower garbage disposal that is suppose to draw only 4.5 amps. Can we just pull another hot 14 gauge wire for the garbage disposal and use the existing white neurtal already there for the dishwasher? Does it matter whether 14 gauge is used rather than 12 gauge wires for either device?
>
>All the wires should usually be #12 BUT if you are serving a pure
>motor load like the disposal, you could use #14. (125% of FLA) Not so
>with the dish washer since it is not a pure motor load.
>Whether they can share the circuit would depend on the nameplate
>rating of the dishwasher.

Mixing 12ga and 14ga on one branch? That sounds like a real no-no,
even if you used a 15A breaker.

Oren

unread,
Dec 8, 2013, 4:49:15 PM12/8/13
to
On Sun, 08 Dec 2013 15:33:08 -0500, gfre...@aol.com wrote:
>The other way around, Without the air gap, waste water from the drain
>siphons back into the dish washer

Yes Sir. Know when or if to knock the plug out.

--
Q: Why do men get their great ideas in bed?
A: Because their plugged into a genius!

Daring Dufas : Hypocrite TeaBillie on welfare

unread,
Dec 8, 2013, 5:08:34 PM12/8/13
to
Hahahahaha.

Dats funny.

Save the call for the unionized fire department.

The Daring Dufas

unread,
Dec 8, 2013, 5:24:23 PM12/8/13
to

Oren

unread,
Dec 8, 2013, 6:12:59 PM12/8/13
to
Or against an animal witness in court.

"Man who had sex with goat faces victim in court"

<http://video.foxnews.com/v/2893082156001/man-who-had-sex-with-goat-faces-victim-in-court/?playlist_id=930909817001>

You can't make this stuff up.
Message has been deleted
Message has been deleted

The Daring Dufas

unread,
Dec 8, 2013, 8:12:55 PM12/8/13
to
Here in Alabamastan he would have gotten capital punishment if the goat
had been white. ^_^

TDD

The Daring Dufas

unread,
Dec 8, 2013, 8:15:46 PM12/8/13
to
On 12/8/2013 5:49 PM, gfre...@aol.com wrote:
> On Sun, 08 Dec 2013 13:15:09 -0800, mike <ham...@netzero.net> wrote:
>
>>> All the wires should usually be #12 BUT if you are serving a pure
>>> motor load like the disposal, you could use #14.
>>
>> I'd consult the building inspector who is gonna approve it on that.
>> He may frown on using less than #12 on a 20A breaker.
>
> Only inspectors who stopped learning the code before they got to
> article 430.
>

I was thinking that many dishwashers have a heating element that could
bring a high resistive load into consideration. ^_^

TDD


Message has been deleted

The Daring Dufas

unread,
Dec 8, 2013, 8:29:04 PM12/8/13
to
On 12/8/2013 5:54 PM, gfre...@aol.com wrote:
> On Sun, 08 Dec 2013 16:35:48 -0500, k...@attt.bizz wrote:
>
>> Mixing 12ga and 14ga on one branch? That sounds like a real no-no,
>> even if you used a 15A breaker.
>
> Not illegal or even unusual.
> If you had a post light and a gate opener at the end of a long
> driveway you might want 12ga on your 15a circuit going down there,
> just for the voltage drop and between the opener and the light, 14
> would be fine.
>
> Is it worth doing to save a nickel on this 3' of 14. Not really but
> it might not be illegal.
>
> Bear in mind there are a few jurisdictions in the US that won't let
> you use 14 for anything but that is a local amendment, made by idiots.
>

The city engineering department around here wants the breaker sized for
the wire. It's possible that in the warmer temperatures we experience
here in Alabamastan, the wire and breakers must be derated to deal with
it to prevent nuisance tripping. I have checked the temperatures of many
electrical panels with my infrared thermometer and they get quite hot at
times under normal loads. Of course I'm looking for that hottest breaker
which could indicate a bad connection. ^_^

TDD

Caulki...@work.com

unread,
Dec 8, 2013, 8:29:18 PM12/8/13
to
On Sun, 8 Dec 2013 09:42:47 -0800 (PST), Edge <wmoy...@comcast.net>
wrote:

-------

Using 14ga wire on a 20A breaker is a code violation, and is dangerous.
Replace all the 14ga with 12ga, or replace the breaker with a 15amp.

The Daring Dufas

unread,
Dec 8, 2013, 8:54:05 PM12/8/13
to
On 12/8/2013 7:26 PM, gfre...@aol.com wrote:
> I mentioned that, we were talking about the wire to the disposal.
>

I believe I've seen them on the same circuit before but I haven't done
house wiring as an electrician in years and the dishwasher here is on a
separate circuit. I'd have to go look at the outdoor breaker panel to
determine what size breaker and wire it is because I didn't install it.
Besides, I have a bit of trouble walking and it's raining hogs and frogs
outside right now. ^_^

TDD

gregz

unread,
Dec 8, 2013, 9:41:30 PM12/8/13
to
I don't see a problem using 15 amp breaker. I use 20 amp breaker feeding 10
ga. To 12 ga. Long run to garage. There can be a long term problem if
things are not labeled.


Greg

k...@attt.bizz

unread,
Dec 8, 2013, 9:57:40 PM12/8/13
to
On Mon, 9 Dec 2013 02:41:30 +0000 (UTC), gregz <ze...@comcast.net>
wrote:
The issue is the next guy who comes along, seeing the 12ga wire,
inserts a 20A breaker. ...but I'll defer to those with a citation in
their hot little hands.

The Daring Dufas

unread,
Dec 8, 2013, 10:16:40 PM12/8/13
to
I believe gfretwell is/was an electrical inspector and he is going by
the NEC. The problem comes in when you have a city engineering
department that has its own interpretation of the National Electrical
Code like where I live. Anyone getting an inspection must do as the
inspector demands even if you believe him/her/it to be wrong. You can
sometimes pull out the code book and win an argument but unless it's an
absolutely insane demand, it's best not to argue with the inspector. ^_^

TDD
Message has been deleted

Stormin Mormon

unread,
Dec 9, 2013, 8:04:54 AM12/9/13
to
On 12/8/2013 8:54 PM, The Daring Dufas wrote:
>
> I believe I've seen them on the same circuit before but I haven't done
> house wiring as an electrician in years and the dishwasher here is on a
> separate circuit. I'd have to go look at the outdoor breaker panel to
> determine what size breaker and wire it is because I didn't install it.
> Besides, I have a bit of trouble walking and it's raining hogs and frogs
> outside right now. ^_^
>
> TDD

One email friend in eastern TN, says it's raining hard
there. Aftermath of that killer storm that passed?

--
.
Christopher A. Young
Learn about Jesus
www.lds.org
.

k...@attt.bizz

unread,
Dec 9, 2013, 7:01:33 PM12/9/13
to
On Mon, 09 Dec 2013 00:09:26 -0500, gfre...@aol.com wrote:

>On Sun, 08 Dec 2013 21:57:40 -0500, k...@attt.bizz wrote:
>
>
>>The issue is the next guy who comes along, seeing the 12ga wire,
>>inserts a 20A breaker. ...but I'll defer to those with a citation in
>>their hot little hands.
>
>"The NEC does not address what an unqualified person might do". I got
>that straight from the NFPA on a proposed change about something
>similar.

>I suppose I could blow everyone's mind by saying it is legal to use a
>40a breaker on 14 ga wire if you are serving a 1HP single phase 120v
>motor with internal overload protection.

How does the overload protection protect the wiring?

>It is a common question in the inspector test.
>
>FLA is 16a (Table 430.248)
>125% of that is 20a (430.22)
>Table 316.16 says a 14 ga copper wire is OK for 20a in the 60c column.
>
>The over current device can be up to 250% of FLA. 16 x 2.5 = 40a
>(table 430.52) if the motor has overload protection.
>

tra...@optonline.net

unread,
Dec 10, 2013, 8:58:54 AM12/10/13
to
On Monday, December 9, 2013 7:01:33 PM UTC-5, k...@attt.bizz wrote:
> On Mon, 09 Dec 2013 00:09:26 -0500, gfre...@aol.com wrote:
>
>
>
> >On Sun, 08 Dec 2013 21:57:40 -0500, k...@attt.bizz wrote:
>
> >
>
> >
>
> >>The issue is the next guy who comes along, seeing the 12ga wire,
>
> >>inserts a 20A breaker. ...but I'll defer to those with a citation in
>
> >>their hot little hands.
>
> >
>
> >"The NEC does not address what an unqualified person might do". I got
>
> >that straight from the NFPA on a proposed change about something
>
> >similar.
>
>
>
> >I suppose I could blow everyone's mind by saying it is legal to use a
>
> >40a breaker on 14 ga wire if you are serving a 1HP single phase 120v
>
> >motor with internal overload protection.
>
>
>
> How does the overload protection protect the wiring?
>
>


The overload protection in this case is inside the motor
itself. It's a common misconception among home inspectors too.
Some of them see a 50A breaker going to an AC compressor and assume
that it has to use the same size conductor that you would use
for a 50A oven. They see a smaller conductor and flag it,
though it's 100% code compliant to use a smaller conductor,
within the rating of the AC unit specs.

tra...@optonline.net

unread,
Dec 10, 2013, 9:01:42 AM12/10/13
to
Wrong, as Gfre has explained. It depends on what the loads are.
Conductors for motor loads are sized differently and you can use
a smaller gauge conductor on the same size breaker that you could
if it were a general purpose circuit.

k...@attt.bizz

unread,
Dec 10, 2013, 1:05:44 PM12/10/13
to
On Tue, 10 Dec 2013 05:58:54 -0800 (PST), "tra...@optonline.net"
<tra...@optonline.net> wrote:

>On Monday, December 9, 2013 7:01:33 PM UTC-5, k...@attt.bizz wrote:
>> On Mon, 09 Dec 2013 00:09:26 -0500, gfre...@aol.com wrote:
>>
>>
>>
>> >On Sun, 08 Dec 2013 21:57:40 -0500, k...@attt.bizz wrote:
>>
>> >
>>
>> >
>>
>> >>The issue is the next guy who comes along, seeing the 12ga wire,
>>
>> >>inserts a 20A breaker. ...but I'll defer to those with a citation in
>>
>> >>their hot little hands.
>>
>> >
>>
>> >"The NEC does not address what an unqualified person might do". I got
>>
>> >that straight from the NFPA on a proposed change about something
>>
>> >similar.
>>
>>
>>
>> >I suppose I could blow everyone's mind by saying it is legal to use a
>>
>> >40a breaker on 14 ga wire if you are serving a 1HP single phase 120v
>>
>> >motor with internal overload protection.
>>
>>
>>
>> How does the overload protection protect the wiring?
>>
>>
>
>
>The overload protection in this case is inside the motor
>itself. It's a common misconception among home inspectors too.
>Some of them see a 50A breaker going to an AC compressor and assume
>that it has to use the same size conductor that you would use
>for a 50A oven. They see a smaller conductor and flag it,
>though it's 100% code compliant to use a smaller conductor,
>within the rating of the AC unit specs.
>

Can you even try to read, Trader?

tra...@optonline.net

unread,
Dec 10, 2013, 1:27:05 PM12/10/13
to
You know, you're remarkably arrogant for someone who knows so
little. You didn't even know how motor loads are sized.
Gfre, who is/was an electrical inspector told you that
you were wrong.


And what I just told you is correct. The overload protection
is in the motor. That protects the motor and the *wiring*
from overload, because the motor is the load. Capiche?
Or would you like to dig your hole deeper?

k...@attt.bizz

unread,
Dec 10, 2013, 4:35:29 PM12/10/13
to
On Tue, 10 Dec 2013 10:27:05 -0800 (PST), "tra...@optonline.net"
You're completely illiterate, Trader.

>And what I just told you is correct. The overload protection
>is in the motor. That protects the motor and the *wiring*
>from overload, because the motor is the load. Capiche?
>Or would you like to dig your hole deeper?

What you told me was completely irrelevant because you CAN'T READ!
Even Cracker Jax should be ashamed with you as an alum.

tra...@optonline.net

unread,
Dec 10, 2013, 6:37:52 PM12/10/13
to
You asked:

"How does the overload protection protect the wiring?"

I replied with:

"The overload protection in this case is inside the motor
itself."

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
of electricity.

Message has been deleted

Ashton Crusher

unread,
Dec 11, 2013, 6:18:05 PM12/11/13
to
On Sun, 8 Dec 2013 09:42:47 -0800 (PST), Edge <wmoy...@comcast.net>
wrote:

>At this home there is a 20 amp breaker in the electrical panel that is pencil labeled as for the dishwasher and garbage disposal. At the junction box on the kitchen wall near the sink we see the 12 gauge wire feeds from the panel. Three 14 gauge wires, hot-black/neutral-white/ground-green, are routed from this box to another junction box underneath the sink through conduit. A whip from the dishwasher is hardwired to the wires under the sink.
>
>We want to add a GE half horsepower garbage disposal that is suppose to draw only 4.5 amps. Can we just pull another hot 14 gauge wire for the garbage disposal and use the existing white neurtal already there for the dishwasher? Does it matter whether 14 gauge is used rather than 12 gauge wires for either device?

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.
0 new messages