Adding light switch to a GFI outlet? HELP

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  #1  
Old 10-26-06, 10:58 AM
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Question Adding light switch to a GFI outlet? HELP

I've done wiring before, but this one has me stumped. Here is what I have: I've added low voltage mini pendant lighting with electronic transformer over a kitchen island. I ran the 14/2 NM-B wiring to the the electrical box that orginally contained a 20amp GFI outlet and a 20amp switch to the garbage disposal. I made a careful diagram of the orginal wiring before unhooking everything and replacing the box with a new one. Orginally there were 4 -14/2 wires coming into the box.
1 set /black-white-ground goes to the line side of the GFI
1 set / black-white-ground goes to the load side of the GFI (outlets)
The other two set of wires going to the garbage disposal and switch for it and are wired like this-- 2 Whites are nutted together and the 2 black wires go to the on/off switch for the disposal.

All of the grounds were wired together with a pigtail to the GFI outlet.

I've tried different combinations and can get power to the new light, however when i turn the new light switch off, it knocks the breaker off, when wired to the GFI. When wired to the Garbage disposal, in one position the light is on, in the other position the light is off but the garbage disposal is on.

How should I wire this 'new' switch to be able to turn it on and off with no problems? It does not appear there is a GFI circuit breaker on my electical panel. Thanks.
 
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  #2  
Old 10-26-06, 01:13 PM
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You cannot wire this new light here. It is against code to run a light off a kitchen counter circuit.
 
  #3  
Old 10-26-06, 02:55 PM
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WeekenderFixer, before we can help you, we've got to clear something up first. Is this a dedicated 15A garbage disposal circuit, or a tap off the 20A kitchen small appliance circuit? If someone has previously (illegally) tapped that garbage disposal onto the 20A small appliance circuit, that's a problem too. If that 20A small appliance circuit is all wired up with 14/2, that's an even bigger problem! When you say the GFCI is feeding "outlets", do you mean that figuratively, or is it literally feeding other GFCI outlets in the kitchen?

14/2 is only legal on a max 15A circuit breaker.. As the existing cabling is 14/2, the breaker must be a max 15A. (And if it's not, it needs replaced with a 15A breaker!)

12/2 cable tying the garbage disposal and/or light onto the 20A appliance circuit would be safe, but illegal. 14/2 cable tying the garbage disposal and/or light onto the 20A circuit is a fire hazard as well as being illegal for a number of additional reasons.
 
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Old 10-26-06, 03:05 PM
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regardless, as Racraft stated, you cannot add a light to a kitchen GFI outlet circuit, Secondly, You cannot run 14 gauge wire off of a 12 guage 20 amp ckt. Point blank, you need to run the switch off of the kitchen lights circuit (IF there's rom on the ckt) or run a new ckt to accomodate this new light.
 
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Old 10-26-06, 03:18 PM
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The OP Wrote: "The other two set of wires going to the garbage disposal and switch for it and are wired like this-- 2 Whites are nutted together and the 2 black wires go to the on/off switch for the disposal."

That sounds to me like the garbage disposal is on a separate circuit from the GFCI and just shares the J-box. Didn't the OP say there were "4 sets of wires". Need to know if the Garbage disposal is on the same breaker as the outlet. Of course maybe I'm reading it wrong and that doesn't change the fact that the wiring is wrong size unless only the garbage disposal is #14 and is a separate 15A breaker.
 
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Old 10-26-06, 04:01 PM
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I am thinking the original poster did not mean to type 14/2, and that it is really 12/2. At least I hope so.
 
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Old 10-26-06, 04:18 PM
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Additional info

My bad on some of the info. Yes, the garbage disposal is on a separate 20 amp circuit that shares the same j-box as the GFI outlet. When i stated the GFI outlet feeds other outlets, it does via the load side of the outlet to the existing outlets on the island. THe orginal wiring is 12/2 not 14/2. I thought since I've read posts concerning bathrooms that one could wire ligthing off of the GFI. My new lights have been ran with 14/2 so it sounds like since that is only rated for a 15 amp circuit I am screwed with trying to use it on a 20 amp circuit. Do you think the 14/2 has been damaged in any way yet? I rechecked and both the GFI and the Garbage disposal are on separate 20 amp circuits.
 
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Old 10-26-06, 04:34 PM
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If your house hasn't burned down, you're OK- the risk is if there is an overload on the #14 cable, that the 20A breaker would allow the #14 to overheat to dangerous temperatures before it would trip. Shut off the breaker to be safe until you've remedied the situation, though.

Are the garbage disposal and the light the only things on this circuit? Unless that's a 2HP garbage disposal, it doesn't need a 20A circuit- a 1/2A or 3/4A should be fine on a 15A circuit. You can either replace the #14 with #12, or replace the 20A breaker with a 15A breaker.

Just to clarify- you can tap off the garbage disposal circuit if the #wire matches the breaker amps, but you can't legally tap the kitchen receptacle circuit for anything else.
 
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Old 10-26-06, 04:42 PM
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Additional info.

I just checked and my dishwasher AND garbage disposal are on the same 20amp circuit. My garbage disposal is a 1/3 hp motor. So if i downgraded my 20amp to a 15 amp, I could then hook up the light to the garbage disposal circuit? If so how would I do that? I sure would hate cutting more holes to run more wiring all over the place, however I want to do a good job as well and not create a fire hazzard. Thanks.
 
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Old 10-26-06, 04:47 PM
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Do this the correct way. Tap either the kitchen lighting circuit, or some other house circuit (that is legal to tap) for the lights.

Do not downgrade the garbage disposal/dishwasher circuit to be 15 amp, and do not upgrade your light wiring to 12 gage just so you can tap this circuit.
 
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Old 10-26-06, 05:20 PM
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Lights: 1A? I don't think this was mentioned.
1/3hp: 7.2A full-load by NEC.
Dishwasher: appx 2A cool dry (according to honda's portable generator guidelines) or 11A according to my dishwasher's UL listing. (5A for the motor, 6A for the heater). I'll have to clamp it sometime and see how (in)accurate that 11A is...

Total: 10-19A non-continuous, depending what numbers you believe.

There shouldn't be a problem with a dishwasher, light and 1/3hp disposal on a 20A circuit and probably not even on a 15A. Simultaneity is low, the cycle time of the disposal is very low. 20A would be better, but the risk of tripping a 15A breaker is slim- even given the worst-case ratings, you'd have to crank on that disposal at full hp load for at least 1 minutes before even the weakest 15A would overload, with the average one probably closer to 10 minutes. In reality, that disposal will never draw 7A unless it's stalled, and that's going to overload the circuit regardless. And, well, I don't trust the UL label. I've yet to see one that's even close to accurate. I'd never install a circuit like this in new construction, but I have a hard time telling WeekenderFixer to tear up his ceiling trying to tap another box when it's perfectly legal to tap off the disposal.

Weekender: can you replace the 14/2 you pulled with 12/2? That's your best bet.
 

Last edited by grover; 10-26-06 at 05:36 PM.
  #12  
Old 10-26-06, 06:15 PM
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Yes, I can replace the 14/2 with 12/2 as I haven't closed or patched the small holes I've already made. Will the load of a 20 amp circuit be too much for a low voltage light with an electronic transformer or were you referring to downgrading the 20 amp to a 15 amp?
 
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Old 11-01-06, 03:25 PM
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Thanks

Thanks for the info. Just so there is a finality to the question here is what I did. I ran 14/2 to the breaker box and installed a new 15 amp circuit. THe breaker box was in the laundry room behind the wall I was installing it in. I cut a hole in the middle of the laundry room ceiling and was able to fish the wire overhead to the outside wall. As an added bonus I installed a convenience outlet nearby too.
 
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Old 11-01-06, 03:25 PM
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Thanks

Thanks for the info. Just so there is a finality to the question here is what I did. I ran 14/2 to the breaker box and installed a new 15 amp circuit. THe breaker box was in the laundry room behind the wall I was installing it in. I cut a hole in the middle of the laundry room ceiling and was able to fish the wire overhead to the outside wall. As an added bonus I installed a convenience outlet nearby too.
 
  #15  
Old 11-01-06, 03:28 PM
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Smile

P>S>

THanks for everyones advise, it helped a lot. Sure I will be posting again for something else. :-)
 
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