I have a half bath that currently doesn't have a power outlet. This half bath was installed by the previous owner's, and, well, let's just say they were idiots and this is not the first project I've had to do to correct something that they did.

Anyway, this half bath has a light switch and one light fixture. The hot and neutral wires go to the switch. Then they go to the light fixture. Normal stuff. Although a quick glance at the wiring showed that there isn't a grounding wire.

They just forgot to add a power outlet. I would like to install the power outlet, on the same wall as the light switch, about 10 to 12 inches from the light switch.

I know I have to install a GFCI in order to comply with current codes.

So, which is the correct option:

1. Tie into the existing hot and neutral wires from the light switch and just run the new wires over and connect them to the GFCI. This would be a "fuse box - light switch/light fixture - GFCI" schematic. Or,

2. Disconnect the hot and neutral wires from the light switch and connect them into the "line" side of the GFCI. Then connect new wires from the "load" side of the GFCI to the light switch? This would be a "fuse box - GFCI - Light switch - light fixture" schematic.

Also, is a grounding wire necessary when using a GFCI?

Thanks.

 

The neutral is never connected to the switch. All white wires aren't neutrals. If you really have black and white to the switch it is probably a switch loop and that may change the answer.

 

I just did a quick glance one day. But, I'm pretty sure that a white wire, and a black wire, were connected to the light switch.

Although, one of them might just be for the electrical needs of the light fixture, and not actually "needed" to provide power to the light switch.

Dang, I wish I had a Dad who was home long enough to teach me these things when I was growing up.

At my age now it's difficult to find the answers without paying a licensed electrician a King's ransom.

 

Don't blame your dad. Despite what we would like to think our parents didn't know it all. Mine couldn't tell me anything about electricity other then not sticking keys in receptacles, now I am licensed. Different people, different abilities and interests.

Pick up a copy of 'Wiring Simplified" and start your own education. Good luck.

 

I didn't mean to imply that I was blaming anybody.

I was just saying that, at my age, it's difficult for this old dog to learn new things.

Electrical wiring would be easier for me to understand now (volts, amps, watts, series circuits, etc) if I had started much earlier.

But, I'm always wanting to learn new things. And, that is what has brought me to this forum.

At this particular moment of time I'm wanting to learn the proper way to install a GFCI.

 

(A) If there is only one cable with two wires at the switch this is not where the power comes in.

(B) If there are two cables at the switch, the white wires are connected together. and the black wires are on the switch then it is likely the power comes in at the switch.

If (A) describes your wiring power probably comes in at the light. If you pull the light you may see a ground wire.

Please do these checks and post back with full details.

(Yes, you can learn. Was past 50 when I used my first computer. Didn't know anyone who knew how to use a computer. Learned how with help from forums. Now use Linux and build my own computers.)

 

I have no problem with, inability of, or lack of desire to learn new things.

That's why I posted this question on this website.

Well, I took a better look at the light switch wiring by actually pulling the light switch out of the wall a little bit instead of just removing the cover.

Here's what I've got:

I have a black, and white, wire that are the main wires coming through the junction box.

The black wire is screwed to the bottom connector of the light switch. A separate shorter piece of black wire (about 4 inches or so) is screwed to the top connector of the light switch.

That top black wire is twisted together with the black wire that leads to the light fixture.

The main white wire doesn't connect to the light switch. It comes through the junction box and is twisted together with the white wire that leads to the light fixture.

There is not a grounding wire connected to the light switch. Although it appears that there is one present in the main wiring harness that houses the black and white wires. I'm uncertain of the grounding wire because, if it is there, then it has been cut back too far for me to know for sure.

So, regarding the black and white wires, and based on what I know about electrical wiring, this appears to be a normal setup.

If this is correct then wouldn't it be a simple matter of just getting a 1ft piece of electrical wiring, connecting black to black and white to white, then connecting those wires to the GFCI?

Or, does the GFCI have to be the first electrical connection in the series? Meaning does the main electrical power have to go to the GFCI first, then run to the light switch, which is then connected to the light fixture?

 

It would seem you do have power at the switch. Does the circuit the light is on provide power to anything other then another bathroom? If the answer is yes then you may not be able to use this circuit for a receptacle. The pros will have to answer if same code applies to a half bath as full bath.

The grounds from the two cables should have been tied together at the switch box. You need to do some tests using either an analog (not digital) multimeter or test light. With power off disconnect all wires at the switch. Carefully position the wires so they are not touching each other or the box. Turn power on and test each cable between black and white to see which is the "hot" cable. If the box is metal test between the box and black of the hot cable. If you get approximately 120v the you may have the grounds joined outside the box.

If no evidence of ground at the box I would probably check for cable slack to see if I could pull more cable into the box and check for ground wire in the cable.

 

You don't need to remove the wires from the switch to test to see which one is hot. Just test with the switch in the off position.

In the strict code interpretation you should run a new 20 amp circuit to power the GFI receptacle.

 

Thank you, Gentlemen.

I appreciate all the advice. I was afraid that I would have to call in the Pro's to run new wiring to the GFCI. It looks like I will have to do that.

As for the wiring circuit running anything else other than that light switch I'm sure it does. But, I have no idea what it would be. I haven't done that much testing to see which circuit breakers run what switches/outlets in my house.

How about this scenario: Instead of connecting a GFCI to the power at the light switch is it against Code to connect the GFCI to the wires off of the light fixture instead?

Yes, I realize that doing so would mean that, when the light switch is off, both the light fixture and GFCI would not have power. But, this is a half bath that is connected to my daughter's room. I can't imagine a time that she would be in there needing to use the power outlet and not have the lights on at the same time.

So, can that be done instead?

 

This is the first thing to do before even starting to plan any electrical projects. With a helper, you can do it in a few hours on a Saturday afternoon.

I cannot overemphasize the importance of fully understanding that not all white wires are neutrals. This one simple misunderstanding has led to the complete failure of countless wiring projects.

 

Thanks, John.

Point taken.

But, to answer my previous question, can a GFCI be fed off the light fixture wiring instead of the light switch wiring?

 

Sometimes. In your specific case (with a white wire connected to the switch), it seems the answer is yes. In fact, feeding it off the switch is not even an option for you.

Of course, I'm just speaking here of what is electrically possible. This project violates several codes in the National Electrical Code.

 

Well, never let it be said that I would knowingly, or willingly, violate any Code of proper conduct.

I have of course. But, I just don't want it to be said.

It looks like I will have to contact a licensed electrician and have him/her give me an estimate on what it will cost to install one GFCI in that half bath.

I appreciate all the advice.

 

Keep in mind that to be code compliant, you will almost certainly need a new circuit run from the panel. Depending on how far apart the panel and the bathroom are, and what is in between, and whether or not you have an open space in your panel, the expected cost has a very wide range.

Also be aware that since the house is likely very old, the electrician will probably find a number of other safety issues, some of which may be more important than this new outlet. Start thinking about what you'll do about that beforehand.

 

Looks like I picked a bad day to quit drinking.

 

If the half of bath is feed by a 20 amp circuit and only feeds that bath you can do that. You can add a GFCI to that circuit anyway you what. Alot of people will put the GFCI on the line side and feed the lights off the load side of the GFCI. You don't have to do it like this. All you have to do is pick up that Hot, Neutral and ground if you can get it from that light switch box. If you have room you could cut out the single gang box where your light switch is at and install a double gang box there. Wire up your switch and put your GFCI there. I see no code voliation here if that run is only to and for your bath.
Jim

 

I don't either, assuming it's a 20-amp circuit. But the chance that all of your "ifs" will be true in an older house is virtually zero.