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I'm planning to add outlets to my garage for a workshop area - my intention is to remove a GFCI outlet in the wall (only outlet in the garage) and replace it with a surface-mounted (conduit) circuit with: 1) three unswitched outlets (all GFCI or downstream from a GFCI) 2) two switched GFCI outlets (one for an overhead light; another battery chargers) My idea for the circuit is: enter image description here The box marked "junction box" is the location of the existing GFCI outlet.

My question is for the 3-gang box I currently have marked as containing two switches and a GFCI outlet. That outlet and the outlet above it would be the switched outlets.

Should I have a separate junction box that sends current to the lower outlets and then to the 3-gang box and downstream outlets, or can the 3-gang box also distribute current to those outlets? If I wire the 3-gang box as planned, it would be wired as: enter image description here

That box would require pigtails with four wires.

The alternative I see is to put a junction box in place of the 3-gang box, then have a 3-gang box with the same planned switches and outlets, but the pigtails would only be three wires.

My instinct is to use a separate junction box to split the circuit, then have the 3-gang box with 3-wire pigtails. Can anybody provide any advice on this?

  • Why is the light going on the GFCI? – ThreePhaseEel Apr 15 at 3:15
  • Because I naively thought that was the way to meet code requirements for a garage circuit. Advice below pointed out that I could put a GFCI at the main junction box, then put regular outlets everywhere else. I'm modifying my plans accordingly – dsideriu Apr 15 at 12:56
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All you need is a box with enough space. Using a box that you actually need anyway and sizing it to have adequate room for the wires and devices is both simpler and less expensive, generally.

I also don't see a point to removing the existing GFCI - just run everything new off its load terminals, you'll not regret having an outlet there at some point in the future. Put a box extension ring on it to bring it out for ease of conduit connection, if you like. There's no need to add any more GFCIs to the circuit - if you have another circuit, sure, but if a GFCI is the first thing on a circuit, and everything else is on its load terminals, everything is GFCI protected, at no extra expense.

The three gang has (countable) 3 hots, 3 neutrals, 1 ground (or 0 ground, depending on your conduit), 3 yokes (that count for 6 wires) If you are actually using conduit, yay, no clamps to count.

12 or 13 wires to count (wires that don't leave the box are free - not counted) presuming 20A circuit and 12 Ga wire, 2.25 cubic inches per "count", minimum volume 27 or 29.25 cubic inches depending if you have ground wires (all of which count as one, none of which are needed with metallic conduit such as EMT.) You can always go bigger if you want more space to work in, but it costs more, usually.

Scanning a few 3-gang boxes, even 2-1/2 inch depth ones have more than plenty of space for this use. 3-1/2 inch depth ones are even more generous.

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Yes, you can make those splices in a 3-gang box.

Why are you using 4 GFCIs when you only need 1? And why switch GFCI outlets, that usually doesn't work very well.

See where your hot and neutral are coming in basically at the GFCI in the switch box. Land that hot and neutral on that GFCI's LINE terminals.

Now connect absolutely everything else to that GFCI's LOAD terminals. Now all the other outlets do not need to be GFCI at all. They are inheriting GFCI protection from this GFCI.

This also avoids the problem of switching a GFCI device, which often trips the GFCI device.

Also note you cannot have a GFCI outlet on the ceiling or inaccessible. Yet another reason why switched GFCIs are a bad idea.

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  • Thank you for the replies! I'm modifying my design based on feedback: 1) Leave a GFCI at the main junction box and put everything downstream on the LOAD terminal 2) Use regular outlets everywhere else 3) Possibly: Use a duplex switch in the 3-gang box to control the outlets I want switched and then consider changing to a 2-gang box if the space is adequate. – dsideriu Apr 16 at 20:57

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