Dishwasher + Disposer wiring help needed

Discussion in 'Electrical Forum discussion & Blog' started by richrc1131, Apr 14, 2009.

  1. richrc1131

    richrc1131 New Member

    Messages:
    88
    Location:
    Central Connecticut
    I recently had to replace my garbage disposer and dishwasher. I reconnected the wiring as it had been on the old machines, but the circuit now trips.

    Here is the setup:

    power --> dishwasher --> garbage disposer --> switch

    To the best of my knowledge, I hooked everything up the same as it had been, I noticed in the directions of the disposer that the green grounding wire needed to be attached to the grounding screw on the unit. I mistakenly connected the ground wire from the incoming power line.

    Would this be the cause of the circuit tripping?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    I'm assuming that the only thing that you can turn on and off via the separate switch is the garbage disposal. ANy time there is a switch involved, you can't just match up white (neutral) and black (hot) wires...you have to know where there're coming from and what they do. It sounds like you've got the switch loop in parallel with the incoming power, so that when the switch is closed to turn the garbage disposal turned on, you've shorted the hot to the neutral. In the process you may have damaged the switch, and might want to consider replacing it as the arc internal to it could deform or melt the contacts.

    The hot from the DW box needs to go to the switch, then through the switch back to the hot lead of the garbage disposal, if the path of power is as you've indicated. if you don't understand this, it might be good to just draw it out. The neutrals would all be tied together, but the hot goes to the switch on one lead of a (probably) romex cable, and back through the switch.

    If none of this makes sense, it may be time for a pro.
  3. richrc1131

    richrc1131 New Member

    Messages:
    88
    Location:
    Central Connecticut
    I will definitely take a look at that configuration. It sounds like the switch is the problem. I wish I had a picture of it (I'm at work right now). I'm not sure how this thing worked before because there was only one peice of romex coming from the switch. I see from your description that the switch needs to be in between the hots for the DW and the disposer correct?
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    the neutrals from the source need to be tied together at each junction - the DW and GD, but the wire from the switch functionally only has hots. At the GD, the hot from the source (DW junction box) cannot connect to the GD, it goes to the switch on one lead, goes through the switch when on back to the GD to turn it on. So, the black at the GD feeding power to it would come from the switch wires.

    following the hot
    source x to DW - and to box where GD is
    Box at (in) GD, hot to switch
    hot (other lead in the cable going to switch - white - put a red mark on it to identify it as a switched hot) goes to the black powering the GD
  5. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689

    Too easy :rolleyes:




    This is an odd setup.

    You have two cables at the DW (in and out)?

    Two cables at the disposal? (will two cables even fit in a disposal jb?)

    One cable at the switch?




    If this ^ is correct (I doubt it).....

    blacks to blacks, whites to whites at DW

    incoming black to outgoing white at disposal
    incoming white to disposal white
    outgoing black to disposal black.

    Bare = green = ground.
  6. richrc1131

    richrc1131 New Member

    Messages:
    88
    Location:
    Central Connecticut
    DW: black to black, white to white, ground to ground

    Switch: black from DW to pole 1 / black from GD to pole 2 / connect the whites / Grounds to green pole on switch

    GD: black to black from switch / white to white from switch/ ground from switch connected to ground on GD connected to ground screw on GD.

    Is this right?
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    No, the cable from the switch is essentially just one wire...the hot feeds one side of the switch, then when on, returns to feed what is being switched. It just takes two wires to do this.

    The hot from the DW area needs to go to the switch, then it comes back when the switch is closed to actually power the GD. So, the actual neutrals (white wires) from real power need to be connected together. There is NO neutral at the switch, so it's white wire becomes hot. That is the one you connect to the black (hot) lead at the GD. It should be marked with a piece of red tape or a red magic marker to indicate that it is something other than a neutral...it is HOT when the switch is on.

    This assumes you've described correctly what you have. It is not common to use the GD as a junction box to wire a switch leg - this means two cables coming in when it is probably only designed for one.
  8. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    Focus dude.

    You said the path was power....DW...disp....switch.


    I asked you if this was correct.


    Now you are implying that it is power....DW.....switch.....disposal.

    If it's power,DW,SW,disp....your hook up is correct.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,245
    Location:
    Cave Creek, Arizona
    dw

    You said the path was power....DW...disp....switch.
    Now you are implying that it is power....DW.....switch.....disposal.

    What difference does it make what ORDER the devices are in? All that counts is how the wiring is arranged and that has ABSOLUTELY no relationship to the physical arrangement of the devices. The dishwasher needs a constant feed, the disposer is fed through the switch, the neutrals are connected together, and the grounds are attached to each device. In this area, because the code calls for a VISIBLE disconnect means, the two devices are equipped with plug in line cords, and a duplex receptacle is installed with the proper wiring to each side and labled as to its application.
  10. richrc1131

    richrc1131 New Member

    Messages:
    88
    Location:
    Central Connecticut
    I was away on vacation, but wow you guys have really gotten deep into this question. Unfortunately, I'm having trouble wrapping my head around the answer(s). There appears to be difference of opinion.
    Honestly, I was hoping someone could just tell me which color wire attaches to which device in sequence. I am going to have to do some research on the answers I've seen. I really want to understand as much as I can instead of just calling a professional. I have so much other electrical work to complete that I need to begin to learn the concepts even if I do contract some jobs out.
    Last edited: Apr 19, 2009
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    The concept here is pretty simple. You need to follow the hot - it must go through the switch so you can control the GD. There are all sorts of ways it could be wired, but the attached show what you said you had and what you might have had...if done as shown (and your power actually comes from where you indicated), either should work.

    Attached Files:

  12. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    He implied that the power/cable went from source,DW,disp,switch.

    The wiring is different if it goes from source,DW,switch,disp.


    It didn't sound right and I questioned him. He didn't respond so?????

    Rich. describe the path and I'll tell you what to do but you gotta help me out here. I can't see your cable/wiring configuation over the internet unless you describe it accurately or post pics.
  13. richrc1131

    richrc1131 New Member

    Messages:
    88
    Location:
    Central Connecticut
    I will post some pics tonight or tomorrow. I am on a job right now (I'm a computer tech by trade). Thank you all in advance for your help.
  14. richrc1131

    richrc1131 New Member

    Messages:
    88
    Location:
    Central Connecticut
    The diagram provided by Jadnashua did the trick. Thank you to everyone for your help with this and I apologize for needing it explained so many times.

    Slowly but surely, I'm learning.
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