Problem wiring garbage disp on sw after gfi!!


Old 09-11-05, 12:24 AM
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Problem wiring garbage disp on sw after gfi!!

I recently installed a new disposal in my kitchen. The power is coming from the panel (20 amp) to receptacle 1 (the line is pigtailed to power the fan hood and this kitchen outlet), the load goes to receptacle 2 which is above the sink in a 2 gang box along with the disposal switch. There are five 12/2 cables coming into this box...2 of which are joined and belong to an unrelated circuit. Of the remaining 3, (A) is the line, (B) is a load to the refridgerator outlet and (C) is the load to the disposal. I am attempting to replace the old outlet with a gfci ahead of the disposal switch but allow the refridgerator outlet to bypass it. I have wired it in the following manner:
(A) and (B) blacks are pigtailed and wired to the gfci line hot; the whites are pigtailed and wired to the gfci line neutral. I have then wired the hot load black from the gfci to the switch, then wired the black from the disposal to the switch. The white from the disposal is wired to the neutral on the gfci. When I turn on the power, I can reset the gfci, but when I attempt to turn on the disposal, the gfci trips. I have checked everything I can think of and have been able to read about and I can't figure out why it would trip. The screws on the switch are not labeled as to load or line and I am assuming it doesn't matter which gets what black. Am I wrong? Can you help?
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Old 09-11-05, 10:49 AM
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First and foremost... I am not an electrical pro.....

A GFCI is designed to trip when "excess current" flows through it (as if a circuit got wet). Your garbage disposal is possibly drawing enough current, especially when it starts, to trip the GFCI. At least, that's what I would look at.

Additionally, depending on your kitchen circuitry, you may have just "busted code" by having something other than a recepticle on a dedicated 20amp GFCI circuit. I know that - here, I am required to have a dedicated 20amp circuit in the kitchen for nothing but outlets..... Or so my inspector tells me...

good luck - and hopefully a pro will chime in soon....
Old 09-11-05, 11:11 AM
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Along with Code issue raised by having other than receptacle loads on the small appliance circuit, why would you want to protect the disposal with a GFI?

How old is your house? Code requirements for kitchen circuits have been quite different than what you describe for quite a while.
Old 09-11-05, 01:23 PM
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Code? What is Code?

Thanks for the responses.

I'm being facetious about the code. I know that code exists and for good reason. My house was built in 1961 and has since been poorly remodeled by a previous owner who apparantly did his own electrical without knowing or caring that code exists. Let me just say he's lucky to be alive and with the things that I keep finding, I'm lucky the house hasn't burned down (he spliced wires without using junction boxes, installed plain romex outside without conduit, had exposed wires in receptacle boxes and much more.) I know there is a good deal of work to be done electrically in my house and plan to take care of it very soon. In the mean time all I wanted to do was replace my disposal that stopped working. When I took the old one out, I found out that when they installed it, they cut off all of the ground wires in the romex they used. So because I found that it was not grounded, I put in the gfi hoping to provide protection to everything in close proximity to the sink, regain use of the disposal until I can deal with the entire kitchen in an upcoming remodel.

As for the dedicated 20 amp circuit, I know code says there should be at least 2, one for the fridge and one for small appliance receptacles. My panel will ultimately need to be upgraded to allow for sufficient 20 amp circuits for the house.

So trying to get the disposal to work behind the gfi, is this a futile effort?
Old 09-11-05, 09:09 PM
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The dsposal needs is own circuit (in some circumstances it can share with the DW), and should definately be off the small appliance circuit. The rane hood should be off that circuit too,and on the GP lighting circuit, unless it is a combo rhange hoo/microwave, which needs its own circuit.
Old 09-11-05, 10:40 PM
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Thanks! I can quite easily move the disposal to the dw circuit since that is all that is on it and that is actually the other 2 wires that come into that receptical box.

Thanks for your help!

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