Running new circuits, is 12/3 cable OK to save runs?

[Mikepier]

I appreciate all the inputs from everyone, thanks.

[RBM]

Personally, I prefer using GFCI receptacles at each and every box, but you could have used a double pole GFCI breaker, then alternated with standard outlets

[RicodJour]

Woot! Even better, I just found the 2009 IRC online. Here's the pertinent page in glorious full color black and white:

No mention of prohibiting holes at any point along the joist. That is odd, as I do remember seeing such a restriction somewhere. Here's another, more specific diagram from Bloomington, IN, but still no restriction on drilling near the joist bearing points:

Here's the main IRC page. Bookmark 'em, Danno! R

[George]

Works fine. Draw the circuit out on the back of an envelope. The GFCI works by looking at the differential in the current of the neutral and the hot leg of its internal outlet and any downstream outlets. If the GFCI is downstream from the shared neutral that neutral under normal operating conditions is carrying the same current as the hot leg. Same is true of the GFCI (if used) on the other leg.

[Steve Barker]

i was told (i thought on this group) that if you put another outlet on the load side it would trip the gfci, OR that if there was a trip, it would trip both legs or something to that effect. I've never actually finished my project, so i don't know. I actually wasn't planning on putting any gfci's on there at all, so i rekon it really doesn't matter.

[Steve Barker]

that's a real good way to get a screw through a wire. Get up in there and drill the holes.

[Steve Barker]

no big deal, but it's Minnesota, not Indiana on the bloomington thing.

[Doug Miller]

Yes: as close to the centerline as possible.

Of course.

No larger than needed; 5/8" is enough to pass two 12/2 cables.

[Steve Barker]

LOL! ya, i hear ya. thanks for the confirmation.

[Steve Barker]

ok but it sounds like i have to have BOTH the gfci's broke out of the shared common at the same point. so i couldn't have one in one box, and the next in the next box down eh?

[aemeijers]

>

yeah, but Indiana has the real one.

[Wayne Whitney]

No, you can do that, you just need to split the mwbc into two circuits at your first box. The GFCI in box 1 protects the first circuit; the GFCI in box 2 protects the second circuit, and all the other recepatcles can be normal receptacles. You feed each GFCI with the shared neutral and one of the two hot legs; and then for downstream receptacles, you feed them from the GFCI load terminals and keep the neutrals separate.

Cheers, Wayne

[Steve Barker]

Understood. But my wire is already in place.

[keith]

Bloomington Illinois is closer to Normal. ;-)

[HerHusband]

You'll need to run dedicated circuits for:

1. Refrigerator
2. Microwave
3. Dishwasher
4. Kitchen Outlets (odd)
5. Kitchen Outlets (even)
6. Kitchen Lighting
7. Range
8. Wall Ovens that are not built-in to the range
9. Garbage Disposal

If the range hood is not part of the microwave, it can be placed on the lighting circuit (not the outlet circuit).

The kitchen outlets need to be GFCI protected, either with dedicated breakers, or by using GFCI recepticles as the first outlet in the run. Ideally, you should run two individual 12/2 cables. While I "think" a shared neutral in 12/3 is allowed in this case, it doesn't cost that much to run a second 12/2 cable. If you go with a shared neutral, you'll need to ensure the circuits are "balanced" in the breaker panel (off each side of the 240 supply) and the breakers tied together with a bar. Keep in mind if you have a problem with one of the shared circuits in the future, or if you end up doing some kind of remodeling, you'll have to shut down ALL kitchen outlets. Keeping the two circuits isolated allows you to shut down only the circuit you are working on.

By the way, the kitchen outlets should be spaced no more than 4' apart, alternating circuits along the run (I spaced ours every 32"). The idea is to balance the load if you have a toaster plugged in one outlet and a coffee maker in the next outlet.

Anthony

[Steve Barker]

dedicated circuits for 1, 2, 3, and 9 are not REQUIRED, but handy. Just a clarification.

Garbage disposer and dishwasher can easily be on one circuit.

[Tom Horne]

The requirement for double pole breakers only applies if both of the ungrounded current carrying conductors terminate on the same strap or yoke. Passing through the same box is not sufficient reason to invoke that rule. There is no problem with the required GFCIs for the counter top receptacles because you only use the 12/3WG for the home run. Once you get to the first kitchen counter top box you split the circuit down to runs of 12/2WG from the first GFCI to the remaining receptacles on that side of the multiwire branch circuit. Likewise for the Microwave/Range hood and refrigerator circuit; which need not be twenty amperes and therefore twelve gauge wire; you can run 14/3WG to whichever box is closer to the panel in wire feet and run 14/2WG from there to the other outlet. That technique recommends itself to the food waste disposer and dish washer loads as well.

[RANT MODE] As for the fella or gal coming along ten years from now if they don't know how to use a tester to assure that all circuits in a box that they are going to work in are deenergized or understand the necessity to keep the two ungrounded conductors on the opposite legs of the panel THEY SHOULD KEEP THEIR UNEDUCATED HANDS OUT OF ELECTRICAL WORK. I will never be willing to try to dumb down electrical work in a futile attempt to make it safe for untrained persons to do the work because I know that it cannot be dumbed down that far. Electricity can kill! Understand it, respect it, or leave it the hell alone! [/ RANT MODE]

-- Tom Horne

[Tom Horne]

Wayne The running of multiple cables through the same holes can cause derating problems. Two 12/3WG cables is only four current carrying conductors. The THHN conductors used in modern day Non Metallic Cable, Type NMC, has an ampacity of thirty amperes; even though the code will not let you use it at more than twenty amperes for most loads. So you can run four of the 12/2WG, 12/3WG or two of the 12/4WG cables through the same holes without any problem. If you run cables having a total of ten or more current carrying conductors through the same holes the ampacity of the twelve gauge cables drops under twenty amperes to fifteen amperes, fifty percent, of the THHN conductor's maximum rated ampacity.

-- Tom Horne

[Tom Horne]

Notches =3D NONE, holes that are spaced several times their diameter apart =3D Quite a few.

-- Tom Horne

[Wayne Whitney]

Right, but new in the 2008 NEC is a requirement for simultaneous disconnect for all ungrounded conductors of a multi-wire branch circuit, so at least a handle-tie is required.

Cheers, Wayne