[dubson]

I got some great help here earlier about my service entrance, so I'm back again.

I'm completely rewiring my 100+ year old house, which is like trying to get a square peg in a round hole. Walls made of 1x12s (um... how do I run a cable?? ), other walls with 2x4 studs sideways (very narrow, and no places for switches). Loads of fun! :) anyway...

I noticed that I could split a receptacle so that it could have two circuits, and this seemed like a great idea to me, so I changed my plans for my den and my kitchen counter, but then wondered if the GFCI requirement would be a problem with the kitchen, and it appears to be so, and it also seems like a bad idea to plug electronics into circuits with a shared neutral. I've already wired the den (with a separate 15A circuit for the computer). I also read that I can only have two receptacles on two split circuits, where in my den I have 9, and 4 in the kitchen. So, my questions are:

1. is there a small limit to the number of split receptacles I can install with the 12/3 cable, or are the 9 in the den okay? Should I instead alternate the circuits at each receptacle?

2. is it correct that a shared neutral is a problem if the neutral becomes open because then the circuits will have 240V, frying all my 120V devices? Any other problems? And is that a problem whether I have split receptacles or alternate the circuits every other receptacle? Should I just not do this and just eat the extra expense of 12/3 over 12/2?

3. I can't do split receptacles on the kitchen counter with GFCI breakers because there aren't any double-pole GFCI breakers, and I assume GFCI receptacles can't be split, correct? Can I instead alternate the circuits, with the first two receptacles being GFCI?

oh, and somewhere tkrussel mentioned that 2 12/2 cables in a 1" hole is fine, but 3 is pushing it. Ugh. I need to make new holes and reroute some things, then. What are the limits for how much cable in a certain-sized hole? I'm using 14/2, 14/3, 12/2, and 12/3 nm. I thought that whatever fit easily would be fine.

I feel like I had another question, but my brain is busy enough. Here's my wiring plans, if anyone is willing to look over them. I've made minor changes, but can't currently edit the source document. The isolated ground receptacles will likely just be normal receptacles. And all heat sources will be gas (water heater, heat, dryer, range).

http://www.venamous.net/electrical-overhead1b.pdf
http://www.venamous.net/electrical-overhead2.pdf

oh, I thought I read somewhere that I can't put the light and fan switches in the bathroom too close to the tub, so I put them (on my plans) outside the room, but there is no space in the wall for a box. There's a small area on the right when entering the bathroom just before the tub which could have switches installed, but I don't think that's allowed (and I've seen plenty of small bathrooms with switches annoyingly outside of them, so I figure they must have had a good reason).

p.s.: I really hate all those DIY electrical books which profess to tell me "everything" I need to know while only telling me half of it, when I'm doing normal standard residential wiring.

[stanfortyman]

OK, I'll try and tackle most of this first.

1) NO, there is no limit, unless of course there is a local amendment.

2) Yes, there is a problem with split receptacles if a neutral becomes open. So make sure your splices are sound.
It IS a code requirement that the neutral is spliced and pigtailed if the multi-wire circuit is spliced in a box. If you split op the multi-wire circuit to two "2-wires" then the neutral spling is no longer required.

3) Two-pole GFCBs certainly ARE available. They just might not be available for your panel if it is old or outdated.

You definitely CAN run three 12/2's in a 1" bored hole. In fact four is fine. More than that and you start to get tight.
And NO, derating is NOT an issue with four 12/2s in a bored hole OR bundled.
With any #12 or #14 cable you can have up to four cables bundled before derating becomes an issue.

You cannot have receptacles or switches over the tub or within the tub/shower area. Just outside the tub/shower IS legal. You just need to use common sense when placing them.