Grounding is continuous throughout the house. In a metal device box, one jumper to the box ground screw should be pigtailed to all grounds flowing in and out of that box.

Thanks. I have a follow-up question, too, because it seems I'll run out of space in that box.

The box is going to have to switches to control lights, one 3-way and one single pole.

So it'll have
- 1 14/2 coming in (line power)
- 1 14/2 going out to light 1
- 1 14/2 going out to light 2 (3-way switched)
- 1 14/3 going in (3-way switch)
- 1 14/2 going out to power a receptacle

plus, because of the splice mentioned above

- 2 14/3 going in/out

If I got this right, that adds up to
- 4 allowances for 2 switches
- 1 allowance for ground
- 17 allowances for conductors

which is 22 -> 44 inches required, plus possibly another 2 for the clamps (do the internal clamps in those blue plastic boxes count?)

I can't look at the box which is currently there right now, it's a typical blue Carlton plastic 2-gang, but I'm quite sure it doesn't have enough volume.

Are there any boxes available that would suit my situation (the wall is 2x6, so there should be enough room), or do I have to go about relocating the 14/3-14/3 splice into its own box?

Also, I guess I could save one 14/2 going out for the lights by making this side of the 3-way hook up to line and running the lights from the other end...

A 4 11/16 X 2 1/8 box with a 1/2 inch 2 gang mud ring will be big enough to do what you are after.

It is generally a good thing to spread wire around between several boxes when you can. It would be great if the 14-3 wires you are splicing could be moved to a box in the attic or basement, the power fed to the receptacle first, and the light run from the other 3 way. While the box size I provided will work it will be full enough that installation of a dimmer or 2 might be pretty difficult.

I have read several conflicting articles about the markings in non-metallic boxes but the manufacturers say that a 1 wire allowance needs to be deducted from the conductor fill stamped into the box for the clamps. Based on what I see it would appear most people, including inspectors, don't seem to be aware of the fact.

If you are stapling your cable within 6 - 8 inches of the box, you don't need any clamps on a plastic box, do you? So you wouldn't need to deduct 1 wire allowance from what's stamped on the box? I'm new at this, and I don't know my butthole from my pie-hole, just looking for some clarification. Thanks.

;)

The plastic boxes "clamps" aren't counted for box fill. Now, if it were a metal box with actual clamps that tighten with a screw, then yes it would count.

All grounds regardless of which circuit they come from are to be connected together.

A "floating" ground would serve no purpose at all. Tie all them babies (grounds) together. They're useless unless they have an uninterrupted path to the panel where they are then routed to your grounding means(cold water and outdoor grounding rod).

They're useless unless they have an uninterrupted path to the panel where they are then routed to your grounding means(cold water and outdoor grounding rod).

Uh, well, not quite. Those equipment grounds are quite useful when they're connected to the center tap of the transformer, which is the principal ground for short circuits, etc. The grounding rod is mostly there to handle lightening strikes.

I don't think the OP was proposing a "floating ground". The question, as I read it, was whether the grounds should be bonded on a per-circuit basis (like neutrals). I think we all agree that they are all bonded together regardless of circuit.

matt m I think I can clarify things for you. See, your pie hole is the one you shovel pie into see, and ...well.... you know.