Dishwasher and disposal same box

Discussion in 'Electrical Forum discussion & Blog' started by Steven Palmisano, Apr 15, 2008.

  1. Steven Palmisano

    Steven Palmisano New Member

    Messages:
    25
    Location:
    Florida
    The wire that is in-place to supply the dishwasher, can I jump off of it to run a connection to a future disposal? I was thinking that I could hook both to a junction box, run a switch for the Disposal and put plugs on both appliances and plug into the receptacle.

    Thanks,

    Steve
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    210.23(2) Utilization Equipment Fastened in Place. The total rating of utilization equipment fastened in place, other than luminaires (lighting fixtures), shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.
  3. Steven Palmisano

    Steven Palmisano New Member

    Messages:
    25
    Location:
    Florida
    Thanks...that sounds like "no' to me
  4. Chris75

    Chris75 Electrician

    Messages:
    608
    Location:
    Litchfield, CT

    Depends. what size wire is supplying the dishwasher and what is the load of the dishwasher? More than likely your good to go.
  5. Steven Palmisano

    Steven Palmisano New Member

    Messages:
    25
    Location:
    Florida
    Not sure Chris...I would quess typical wiring, and same typical DW and Disp. draw

    thanks
  6. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    I think you have to parse the sentence from the NEC to see if it works.

    The first question is, what is meant by "fastened in place". It is important to note that a piece of equipment can be both cord-and-plug-connected and fastened in place.

    210.23(A)(1) discusses requirements for cord-and-plug-connected equipment not fastened in place.

    210.23(A)(2) discusses utilization equipment that is fastened in place, and the restrictions on load where lighting units and/or cord-and-plug-connected equipment not fastened in place is also supplied.

    Every dishwasher (except the roll-around kind) and every disposer that I have ever seen was fastened in place. A dishwasher that I installed last week was fastened to the bottom of the countertop, and the disposer was certainly fastened in place at the bottom of the sink. In that case, the restriction of 210.23(A)(2) does not apply.

    Therefore, the limit on whether you can connect a dishwasher and a disposer to the same circuit depends on whether the total load exceeds the branch circuit rating.

    My dishwasher is rated at 11.5 Amps and the disposer at 8.1 Amps for a toal of 19.6 Amps. They are both legally connected (hard-wired) to a 20 Amp circuit (circa 1965).

    One restriction on using a receptacle is that there is a code section (I am not going to search for it now.) that requires that cords for appliances be provided or approved by the appliance manufacturer. Most dishwashers and disposers don't come with cords. I would plan on using a piece of AC or MC, or LFNC.

    In the new house where I installed the dishwasher last week the licensed electrician had provided a 5 ft length of 14/2 NM (Romex) coming up through the floor at the back of the dishwasher space.
  7. taysan

    taysan Member

    Messages:
    113
    Location:
    Toronto, ON Canada
    And from a layman's practical point of view, how often are you going to want to run your dishwasher and disposal unit at the same time anyhow? You'd need ear protection.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,293
    Location:
    Cave Creek, Arizona
    outlet

    The two appliances are connected to the same circuit more times than thye are separate.
  9. frenchie

    frenchie Jack of all trades

    I beg to disagree with everyone... the NEC also says, I believe, that appliances have to be installed according to the manufacturer' instructions?

    I've never seen dishwasher installation instuctions that didn't call for a dedicated circuit.

    So, while it'd probably work (because, as pointed out, what are the odds you'd run them at the same time?)... it wouldn't be legal.
  10. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,713
    Location:
    Central Florida
    You're seeing one now...

    My Kenmore DW installation instructions' Electrical Requirements are:

    You must have:
    o 120-volt, 60Hz, AC-only, 15 or 20 amp., fused electrical supply.
    o Copper wire only.

    We recommend:
    o A time-delay fuse or circuit breaker.
    o A separate circuit.
  11. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,713
    Location:
    Central Florida
    Actually, I've often thought it might be a good idea to run the disposer during the dishwasher's drain cycle, to thoroughly grind up any big pieces left by the dishwasher's macerator (I think it's got one). Noise is not a big deal these days, but the total current required was a deal-killer.
  12. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    More than likely, you can.


    All DW/Disp here share a dedicated 20 amp circuit. If it is an older home and the DW circuit has other stuff on it you would be pushing it.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,293
    Location:
    Cave Creek, Arizona
    disposer

    The big chunks, and little ones also will stay in the disposer and then be ground up the next time you operate it.
  14. Johnny C

    Johnny C Electrician

    Messages:
    23
    Location:
    Mass. & now Virginia Beach, VA
    Dishwasher and Disposal on same circ.

    Good answer "Frenchie". UL listed product must be installed in accordance the their Labeling and Listing requirements, NEC 110-3(B).
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