How can I improve the wiring under the sink for a garbage disposal?

Question

My vegetable sprayer line broke yesterday, which led me underneath my sink. It wasn't until I was kneeling in a large puddle of water with the line draining on me and the floor that I realized how bad the wiring was for my garbage disposal:

This obviously needs to be addressed. My question is which of the following approaches will solve my problem and won't kill the next tenant?

• Cover the J-box with a plate that has a hole and let the romex come through
• Wire in an outlet (half-hot) and convert the romex to a 3-prong plug
• Wire in a GFCI outlet (half-hot) and convert the romex to a 3-prong plug
• Something else?

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Completed project:

Answer 1

The answer to your question depends completely on whether this node in the circuit is GFCI-protected. GFCI protection is an absolute must for your disposer; it's a high-amperage electric motor hooked up to your kitchen drain.

Since this J-box doesn't have a standard 3-prong outlet, you'll need to find another outlet on the same circuit; look for a countertop outlet nearby. Plug in an outlet tester (like the one below, available for $5-10 from your local big-box home improvement store), turn on the disposer, and hit the black button on the tester to short hot to ground, inducing a "ground fault".

If the disposer has GFCI protection, it will cut out, and you're golden as far as circuit safety. If not, you definitely need to rewire this J-box with a GFCI outlet.

Even if the disposer is GFCI protected, you have other problems. The outlet is in a "wet" place; you hope that the under-sink area never leaks, but there is always, always, a plumbing emergency at the kitchen sink at some point. To avoid a continuous ground fault through contact with standing water in the J-box (which would prevent you from resetting the GFCI until the whole area dried out), you should seal this area as best you can. A little adhesive spray foam to fill the gap between the wall and the back of the cabinet, followed by a layer of silicone adhesive caulk to waterproof the spray foam (people think spray foam is waterproof, but it really isn't), and a child-resistant outlet and plate with a rubber or neoprene gasket (and/or another dab of silicone) should keep the water out in any situation less than a full flood.

Answer 2

If you don't have the GFCI tester that KeithS mentioned, they are cheap and good to have. But until then, just hit the test button on the GFCI outlet in the kitchen and see what turns off.

As far as wiring coming straight out of the box like that, I suspect it's against code. Every wire should go through a knockout in the back of the outlet in a secure way, either using the plastic tabs or a securely screwed knockout clamp:

With the current setup, there's a risk of pulling on the wires and loosening the connection. Even putting a blank plate with the wire coming through doesn't secure the cable and connections. But as the fellow DIYers below point out, you can get a box cover with a knockout and use that to clamp the wire in (and also shield it from some water or physical contact):

Answer 3

Pretty good advice so far.

If it were a new install, then it would not be "J" boxed under the sink, but direct to the switch and GFI protected.

But with the situation you have now, unless you want to fish wires up the wall to the switch, let's make it safe.

1. Install a tamper proof GFI receptacle into the box as pictured and install a gasketed cover.

2. Install a 3 prong plug to the cord from the disposal. It should be a 3 wire cord if made or installed in the last 20 years. You can also find plugs with a rubber bushing that will fit snug around the existing cord. If it is not 3 wire, open the hatch on the disposer and install a new 3 wire piece of SO or SJTO cord with a molded plug already attached.

Even if the circuit is already GFI protected, a second GFI at the point of power will not hurt, and give you more protection in a future geyser blast!

All this is assuming that the feed romex is actually a true 3 wire circuit, hot, neutral, ground.