Disp & Dishwasher on single 20A ckt?

[Ragin Cajun]

We do the electrical design for apartment houses. The question came up regarding why can't we put both the dishwasher and disposal on a single 20A circuit plugging both into a single 20A GFCI.

The disposal is rated at 3/4 HP, 6A, 120V.
The dishwasher is 120V, 1.2A motor, and 8.1A total
Both appliances are GE.

Looking at those actual nameplate numbers I see no reason not to put both of them on a single 20A circuit. The dishwasher would plug directly into a GFCI, and the disposal into a switched receptacle sub-fed from the GFCI with both mounted in a 2 gang, non-Metalic outlet box under the sink.

Years ago when I remodeled my own kitchen including a new panel board, I put both appliances on a single 20A circuit and never had an issue. (Didn't need to put them on GFCI back then.)

Saving just one AFCI circuit, wiring, and a GFCI for both appliances in each apartment unit in a 48 unit apartment complex adds up to over $4,800. We are working on 4 or 5 complexes at the moment and that's serious $$$!

Have I missed something? BTW, we are under the 2014 NEC in SC.

Thanks,

RC

 

[user 100]

We do the electrical design for apartment houses. The question came up regarding why can't we put both the dishwasher and disposal on a single 20A circuit plugging both into a single 20A GFCI.

The disposal is rated at 3/4 HP, 6A, 120V.
The dishwasher is 120V, 1.2A motor, and 8.1A total
Both appliances are GE.

Looking at those actual nameplate numbers I see no reason not to put both of them on a single 20A circuit. The dishwasher would plug directly into a GFCI, and the disposal into a switched receptacle sub-fed from the GFCI with both mounted in a 2 gang, non-Metalic outlet box under the sink.

Years ago when I remodeled my own kitchen including a new panel board, I put both appliances on a single 20A circuit and never had an issue. (Didn't need to put them on GFCI back then.)

Saving just one AFCI circuit, wiring, and a GFCI for both appliances in each apartment unit in a 48 unit apartment complex adds up to over $4,800. We are working on 4 or 5 complexes at the moment and that's serious $$$!

Have I missed something? BTW, we are under the 2014 NEC in SC.

Thanks,

RC

I don't have my book w/ me, so I'm flying a little blind here - but look at 210.23 (A)(???) I believe and the 50% rule, util equip fastened in place etc- you're ok with the setup you want if the dw& disp are the only thing on the ckt

 

[Ragin Cajun]

Sewwt.

The circuit is dedicated to only the disposal and the dishwasher.

RC

 

[user 100]

I don't have my book w/ me, so I'm flying a little blind here - but look at 210.23 (A)(???) I believe and the 50% rule, util equip fastened in place etc- you're ok with the setup you want if the dw& disp are the only thing on the ckt

Sewwt.

The circuit is dedicated to only the disposal and the dishwasher.

RC

Reference from the 2014:

210.23(A)(2)-

Utilization equipment fastened in place:


"The total rating of of utilization equipment fastened in place, other than luminaires, shall not exceed 50 percent of the branch circuit ampere rating where lighting units, cord and plug utilixzation equipment not fastened in place, or both are also supplied."- so no 50% rule.

So dead end at dw and disp and you're legal.

 

[kwired]

Been running a single 20 amp circuit for years for both those appliances, never got a correction notice or complaint that this combination trips the breaker, even when not knowing exactly which appliance models will be selected at rough in time (which is nearly every time).

 

[JFletcher]

For your mass installed DW/GD combos, both being less than 10A ea, I see no reason they cant share a 20A circuit.

VA electricians are gonna have so much fun with these AFCI when (if) they become mandatory here for anything other than bedroom outlets.

 

[kwired]

For your mass installed DW/GD combos, both being less than 10A ea, I see no reason they cant share a 20A circuit.

VA electricians are gonna have so much fun with these AFCI when (if) they become mandatory here for anything other than bedroom outlets.

Actually any that pay attention to what is happening elsewhere will have learned a little about them before finding out some things the hard way.

 

[MasterTheNEC]

For your mass installed DW/GD combos, both being less than 10A ea, I see no reason they cant share a 20A circuit.

VA electricians are gonna have so much fun with these AFCI when (if) they become mandatory here for anything other than bedroom outlets.

Actually , they are required in VA outside of the bedroom if you are doing multifamily dwellings that bring in the IBC as part of their building code. The AFCI amendment only applies to one and two family dwellings and those governed under the IRC. If the building is being constructed under the International Building Code then VA's amendments mean nothing to those "dwelling units" in the multi-family building.

 

[peter d]

My standard practice is to run a single 20 amp circuit to serve both and I have never had an issue with that. It saves time and labor especially with the AFCI/GFCI rule. IMO anything about that is overkill, especially since the disposal never runs for more than a few seconds anyway.

 

[peter d]

Looking at those actual nameplate numbers I see no reason not to put both of them on a single 20A circuit. The dishwasher would plug directly into a GFCI, and the disposal into a switched receptacle sub-fed from the GFCI with both mounted in a 2 gang, non-Metalic outlet box under the sink.

I'm curious why you would do it this way as it is more labor intensive. If it were up to me, I would use a split wired duplex receptacle in a single gang box, with a switch loop up to the disposal switch. I would protect it with a dual function breaker.

 

[MasterTheNEC]

We do the electrical design for apartment houses. The question came up regarding why can't we put both the dishwasher and disposal on a single 20A circuit plugging both into a single 20A GFCI.

The disposal is rated at 3/4 HP, 6A, 120V.
The dishwasher is 120V, 1.2A motor, and 8.1A total
Both appliances are GE.

Looking at those actual nameplate numbers I see no reason not to put both of them on a single 20A circuit. The dishwasher would plug directly into a GFCI, and the disposal into a switched receptacle sub-fed from the GFCI with both mounted in a 2 gang, non-Metalic outlet box under the sink.

Years ago when I remodeled my own kitchen including a new panel board, I put both appliances on a single 20A circuit and never had an issue. (Didn't need to put them on GFCI back then.)

Saving just one AFCI circuit, wiring, and a GFCI for both appliances in each apartment unit in a 48 unit apartment complex adds up to over $4,800. We are working on 4 or 5 complexes at the moment and that's serious $$$!

Have I missed something? BTW, we are under the 2014 NEC in SC.

Thanks,

RC

Just to assist you. Here is the commentary from the 2014 NEC Handbook (Authors Opinion)

The quote below is regarding Section 210.23(A)(2)...

"The requirement does not apply to a branch circuit that supplies
only fastened-in-place utilization equipment. In that case, the
entire rating of the branch circuit can be applied to the utilization
equipment. For example, a 20-ampere branch circuit dedicated to
supplying a waste disposer and a dishwasher is not restricted to
either one of the appliances not exceeding 50 percent
(10 amperes) of the branch-circuit rating although the combined
load of the two appliances cannot exceed 20 amperes."

Should clear it up for you.

 

[Ragin Cajun]

I'm curious why you would do it this way as it is more labor intensive. If it were up to me, I would use a split wired duplex receptacle in a single gang box, with a switch loop up to the disposal switch. I would protect it with a dual function breaker.

Call me paranoid, but I distrust AFCI's no. Seems that a dual AFCI/GFCI would be even worse. I like having the GFCI near the load so the homeowner can easily find it. Guess I'm old school. RC

 

[kwired]

Call me paranoid, but I distrust AFCI's no. Seems that a dual AFCI/GFCI would be even worse. I like having the GFCI near the load so the homeowner can easily find it. Guess I'm old school. RC

How often do you hear of a GFCI tripping for a DW or DSP unless there is a problem with the appliance? The AFCI - is required regardless of whether you like it or not so would you rather pay for one or two?

 

[peter d]

Call me paranoid, but I distrust AFCI's no. Seems that a dual AFCI/GFCI would be even worse. I like having the GFCI near the load so the homeowner can easily find it. Guess I'm old school. RC

I see. Considering this is an apartment complex and you're looking for cost savings, I would forgo your dislike for the dual function breaker and spec them. The electricians who wire these complexes will thank you too. I'm also assuming that the panel will be inside of a smallish apartment so it wouldn't be hard to find the breaker, no?

 

[templdl]

Been running a single 20 amp circuit for years for both those appliances, never got a correction notice or complaint that this combination trips the breaker, even when not knowing exactly which appliance models will be selected at rough in time (which is nearly every time).

How about a single home run circuit by running a single 12/3 w/g?

 

[kwired]

How about a single home run circuit by running a single 12/3 w/g?

Certainly allowed. Does not save any installation cost when you look at the AFCI requirements and what a two pole AFCI (if even available in the circuit breaker series you might need) would cost. Also needs more then a simple duplex at the load end if GFCI protection is not at the supply end.

 

[goldstar]

The dishwasher would plug directly into a GFCI, and the disposal into a switched receptacle sub-fed from the GFCI with both mounted in a 2 gang, non-Metalic outlet box under the sink.

You could save the extra labor and materials by having your customer purchase a "batch feed" type disposal (one that utilizes the drain plug/switch). That way you only have to install the GFCI receptacle.

 

[templdl]

Certainly allowed. Does not save any installation cost when you look at the AFCI requirements and what a two pole AFCI (if even available in the circuit breaker series you might need) would cost. Also needs more then a simple duplex at the load end if GFCI protection is not at the supply end.

Catch 22 it appears.
Thanks
If cost is a factor and pricing has to be competitive it I not a good way to go.

 

[Ragin Cajun]

Attached is how I now propose to feed the disposal and dishwasher.

Thanks for all the terrific suggestions. Even an old dog can take some good advice.

RC

 

[kwired]

Let's remember the disposer doesn't need GFCI (as of 2014 NEC), but depending on how your AHJ interprets the within six feet of the sink may still require GFCI for the receptacle.

Then comes the GFCI requirement for dishwashers, that was added for the wrong reasons in 2014 - but outside of that could still have a requirement for a receptacle depending on location and interpretation of within six feet of sink.

Then the kitchen was added for AFCI requirements - making the dual function AFCI/GFCI breaker the most obvious solution in most instances.

If you are not on the 2014 yet most of this don't apply to you, but you still can run both appliances on a single 20 amp circuit that contains no other outlets with little or no objection from NEC.