How to add GFCI to a box with one outlet controlled by a switch?

Question

I'm pretty inexperienced when it comes to electrical work, though I do know my way around a circuit diagram, thanks to some EE courses in college. I think this is one I can do myself, I just would like some validation that I understand the wiring correctly and that my plan is acceptable.

---

Current Configuration

I have an outlet and single pole switch in one box next to the sink in my kitchen. The switch controls the top outlet, and has plugged into it a fluorescent light that is mounted above the sink. The bottom outlet is always hot, and I currently have my microwave plugged into it. I opened up the box to look at the wiring (with the breaker off, of course), here's a sketch of what it currently looks like inside:

One additional note on the setup - my fridge is connected to the same breaker as this outlet, and I'm 90% sure it's further down the line. I'd rather not put the fridge on the GFCI load, as I don't want my food to rot if it randomly trips while I'm out.

---

Questions

I want to protect the outlets next to the sink with GFCI, but I want to keep one of the sockets controlled by a switch, and I don't think I want to put the rest of the circuit on the GFCI load, because I don't want the fridge on GFCI.

1. What's the simplest and/or best way to rewire to achieve this?
2. I'm not sure which of the lines leading into the box comes from the breaker box - is there an easy way to test this?
3. Is there an easy way to test for sure whether or not the fridge outlet is before or after the sink outlet?

---

Tentative plan

I know I can get a GFCI/switch combo unit at Lowe's for ~$30. I'm thinking I could replace the switch with that, and wire the existing regular outlet to the load end of the GFCI (with the top outlet wired through the switch), but have the rest of the circuit wired to the line (i.e. not on the GFCI load). I think this does what I want, plus gives me a bonus GFCI-protected outlet by the sink.

Something like the first diagram in the answer to this question, actually, except with the top outlet connected in place of the garbage disposal, and the bottom outlet also connected to the load.

Does this sound reasonable?

Answer 1

Ok I read your question a few times, so hope I understand what you want to do. You want GFI prtection on the outlet , but no GFI protection to the fridge. This will be easy to do if you can affirm that the load wire leaving the j-box where the switch and outlet are located, is actually the feed for the fridge. To check this out, you need to turn off the power, check the outlet at the sink and fridge to be sure they are ,in fact on same circuit and off. Now disconnect all the wires from the outlet and any wirenuts so everything is isolated. Now, carefully turn the power back on and check the hot (typically black) leads to ground with a volt meter to determine which one is the feed/source wire. Mark this with some red electrical tape. Double check to see that the fridge outlet is still dead.

Next, turn off the power and wire nut the black source wire and associated white neutral to the black and white wires you suspect goes to the fridge.( black to black, white to white) Turn the power back on and check with your voltmeter at fridge outlet again. If there is voltage there now, you have found the right feed wire to the fridge outlet. An alternate method of finding that wire with the power off, is to use an ohm meter. Assure the power is off, then twist the black and white together on the wire you suspect goes to fridge and check the hot and neutral slots of the fridge outlet with your ohm meter. the meter should show 0 ohms or "short circuit".

Now that you have identified the hot feed and load wire to fridge in your box, you can wire it so only the counter outlets are GFI protected. Put the source black wire together with the fridge black wire, along with a separate 8 inch piece of black wire (pig tail) and wire nut them all together. Use the 8 inch black wire to feed your switch/gfi hot. The neutrals tie together as usual with an extra pig tail for your GFI outlet neutral. Obviously, trim the pig tails to a comfortable length to fit in your box before connection to the GFI.

Since all outlets must be GFI protected in the counter outlet and since you cannot split a gfi outlet top and bottom like in your diagram, you have to do your light differently from your previous plan. I would suggest using a switch/single outlet device wired from the load side of the gfi. Wire the switch in series with this single outlet. This means only the single outlet is switched and gfi protected. You must have gfi protection on this outlet, as someone could unplug the lights and use it for something else.

Hopefully, one of my artistic buddies can do an edit and add a nice diagram depicting what I have outlined for you.