How to add GFCI-protected switches and lights to a 2-wire garage circuit

Question

In my garage, I have an outlet on the ceiling powering the garage door opener. It has black and white wires coming to the socket, and no ground that I can see.

I've run some conduit along the ceiling over to a workbench area, where I want to install a few outlets at bench-level and some ceiling lights controlled by a switch. I know I need to use a GFCI for the outlets, at least. I have two questions about how to run the wiring:

1. Should the outlets be wired in series or parallel?
2. Should the lights be before or after the GFCI?

I've made some diagrams to work through the choices! Is there anything I'm missing?

All on GFCI

The power comes in the lower left side. In this option, everything is on the load side of the GFCI, and the outlets are wired in parallel.

Lights before GFCI, Outlets in series

This is much simpler. This should prevent the lights from going dark if the GFCI trips, correct? Are there any drawbacks?

Answer 1

Your first diagram is almost correct. The receptacles need to be wired in parallel, but so do the lights. The lights can be GFCI protected, but they're likely not required to be (unless they're in a shower in your garage).

Something more like this

You also need a neutral at the switch, even in you don't use it. So it might look more like this.

Answer 2

You are required to GFCI protect grounded (3-wire) light fixtures installed on ungrounded (2-wire) circuits. See 410.44 exception #3:

Exception No. 3: Where no equipment grounding conductor exists at the outlet, replacement luminaires that are GFCI protected shall not be required to be connected to an equipment grounding conductor.

Answer 3

I am not an electrician. You should be using a licensed and bonded electrician. Your local municipality may require a permit. Mains voltages can KILL YOU DEAD.

That said, I think I know what I'm doing, but use this advice at your own risk. I would recommend you don't wire lights after the GFCI, unless the bulbs will be outside and potentially exposed to the weather. That's what you describe in your second diagram, but there are some problems with it:

1. As another answer mentioned, bulbs should be wired in parallel, not series. That is to say, from the switch, there should be hot to each bulb, with neutral returning from each.
2. The outlets protected by the GFCI should also be in parallel. That means, the load terminal on the GFCI should be wired to the hot terminal on both extra outlets.
3. In order to detect current leakage (the GFCI's main purpose), the neutral wire of the protected outlets need to feed back through the GFCI. That is why your GFCI has five terminals: Gnd, Line Hot, Line Neutral, Load Hot, and Load Neutral.

Since I don't feel like making a drawing, I'll explain in terms of electrical nets. IOW, for each net below, there should be a connection between each device listed after the net's name (and wire color).

• Ground (green): from electrical panel, to every single device with a green screw (just wire them all together in the back of each box)
• Line (black): from electrical panel, to light switch, and to GFCI (Line Hot)
• Switched Line (black): from light switch, to both bulbs
• Isolated Line (black): from GFCI (Load Hot), to both outlets
• Isolated Neutral (white): from both outlets, to GFCI (Load Neutral)
• Neutral (white): from both bulbs (via wire nut in switch box), and from GFCI (Line Neutral), to electrical panel

If your lightbulbs will be outdoors and you do want to protect them from ground faults, then the wire to the switch box (both line and neutral) should come from the Load side of the GFCI, rather than directly from the panel (or the GFCI's Line side). You can physically wire it from the GFCI box, or from either of the outlet boxes, whichever is closest to your switch box.

There may be other code requirements in your area that a local electrician can help you with. Eg., use 12AWG for 20A breakers, or 14AWG for 15A, and staple the romex wires to the stud close to the box they run into. Leave about 10-12" of wire hanging out when roughing things in, and strip the tips as specified in the wire nut packaging, or the QuickWire push-in hole guides. Use wire nuts rated for the number and gauge of wires each will connect. Don't burn your house down. :)

Answer 4

mine is similar in first diagram...on 3 wire...load side neutral can't share when coming back from line side cause my situation..source is in the end of the room from inside while gcfi is on outside wall from other side of room in my detached garage that share both rooms...thing is ..one is incomplete room..everything is cover but its barebones that i can see the attic crawlspace next door room..and easy to see the wiring and the backing of the outlet boxes only one side of room if i want to work on...this room did not had lights or gcfi outlet just weather proof standard outlet is not connected where source from end the barebone tool shed hall..there is a outlet that i can work on to and add more outlets in that room and complete the circuit for outside gcfi outlet ..so i use mix of 12/2 and 12/3 for my setup..i loved about diagrams ..i can make my version here