How to replace switch/outlet to GFCI/switch combination

Two devices in one package can make for twice the confusion

GFCI/switch combinations are a common cause of DIY confusion, as they have more, and more varied, connections than most other electrical devices one can get at the hardware store.

In your case, you have the GFCI portion wired correctly, but the switch is what has you down. It's actually nothing special, just a plain single pole switch with no internal connections whatsoever to the GFCI. However, you seem to have your hots, neutrals, and grounds confused with regards to the switched load. What they mean by "The LOAD must be properly connected to NEUTRAL and grounded." has nothing to do with the wiring in the GFCI box -- in fact, the wiring of the switch to neutral and ground is why the switched load isn't working right now! It simply means that the load itself must be wired correctly and not in a bizarro way (such as across two hots, from hot to ground(eek!), or with a switched neutral). In fact, right now, the load can't work because there's no voltage across it with one end wired to the neutral (and ground) and the other wired back to that same neutral.

To get this all working I would:

• Disconnect the switch-wire going to the white wire bundle from the white wire bundle, and remove the pigtail from the switch/black wire #3 junction to ground.
• Cap off black wire #2 by itself since you don't yet know where it leads. (Sooner or later, you'll find the thing that doesn't work, and then you'll know what that black wire was feeding.)
• Connect one black wire from the switch in with black wire #1 and a black pigtail to the GFCI's LINE HOT terminal.
• And connect the other black wire from the switch to black wire #3.

Grounded circuit (green/bare ground wire wired properly):

• Push "Test" on the GFCI protective device, and it trips -> PASS
• Push "Test" on the GFCI protective device, and it does not trip -> FAIL
• Push "Test" on a plug-in GFCI tester, and it trips -> PASS
• Push "Test" on a plug-in GFCI tester, and it does not trip -> FAIL

A fail here indicates the GFCI unit is probably defective.

Ungrounded circuit (green/bare absent or defective):

• Push "Test" on the GFCI protective device, and it trips -> PASS
• Push "Test" on the GFCI protective device, and it does not trip -> FAIL
• Push "Test" on a plug-in GFCI tester, and it trips -> FAIL FAIL FAIL
• Push "Test" on a plug-in GFCI tester at the GFCI receptacle, and it does not trip -> PASS
• Push "Test" on a plug-in GFCI tester at a downstream protected outlet, and it does not trip -> MEANINGLESS

Fail at the GFCI device probably indicates it is defective.

Fail on the plug-in GFCI tester (i.e. it trips!) indicates they have bootlegged ground at the GFCI receptacle- attached the neutral wire to both neutral and ground. It will seem to work at the GFCI, but is still dangerous.

Bootlegging ground at a downstream GFCI receptacle is a mistake, because one of several electrical faults could put 120V on the the grounds, e.g. the cover plate screws or a machine chassis. However this is difficult to detect, since a properly wired downstream receptacle will behave exactly the same way. This means for ungrounded downstream receptacles, plug-in tester testing is completely meaningless.

Once you have settled the question of bootlegged grounds, here's how you test an ungrounded GFCI. Plug your GFCI tester into your handy dandy 2-3 prong "cheater" - the kind with a short green wire as a pigtail. Extend that green wire all the way to a reliable ground source, e.g. the panel in the basement. Now, the GFCI tester should work normally, since you have rigged a proper ground to it.

GFCI protection is pretty effective, and I would be confident in an ungrounded circuit if it has GFCI protection. However if you are unable to get the external device to trip, you'll need to pop the cover off and see if the ground is present, missing or bootlegged.