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

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I would think that staying a distance D (depth of member) away from the bearing zone would be sufficient, but I would stay 2D away to be sure.
Cheers, Wayne
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Yep, you're right. I have a better diagram in my Code application, but it's more work to get it online, so I took the - surprise! - lazy way out and posted a link that answered Mike's question. I'll try to get a more definitive diagram posted.
R
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Woot! Even better, I just found the 2009 IRC online. Here's the pertinent page in glorious full color black and white: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_5_sec002_par027.htm
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: http://www.ci.bloomington.mn.us/handouts/53/53znotch.pdf
Here's the main IRC page. Bookmark 'em, Danno! http://publicecodes.citation.com/icod/irc/2009/index.htm
R
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On 10/4/2010 5:23 PM, RicodJour wrote:

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_5_sec002_par027.htm
no big deal, but it's Minnesota, not Indiana on the bloomington thing.
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Steve Barker
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On 10/4/2010 10:27 PM, Steve Barker wrote:

yeah, but Indiana has the real one.
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aem, former 47401 resident, sends...

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Bloomington Illinois is closer to Normal. ;-)
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The best place for holes in a joist is at the neutral axis where the joist is only stressed in bending. What this means in practice is to stay away (maybe 2 feet?) from the bearing points (over and under wall framing) and then to put your holes in the middle of the joist.

Yes, in fact if you would find it easier, you can feed all four 12/2s, or two 12/3s, without any problem NEC-wise.

The maximum size hole you are allowed to drill is quite a bit more than what you will need, e.g. a 1.25" hole for 4 12/2s would be fine.
Cheers, Wayne
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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
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That is correct. I didn't bring it up because as you noted it only affects installation of 5 or more bundled 12/2s.
Cheers, Wayne
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Yes: as close to the centerline as possible.

Of course.

No larger than needed; 5/8" is enough to pass two 12/2 cables.
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ass because someone way back used a common nuetral on separate circuits. White wire bit me - I traced it to a yard light that was always on.
Harry K
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Harry K wrote:

In that case there should have been at least 2 hot wires in the box, one of which remained hot when you killed the circuit you were working on.
"Hot neutrals" are the reason the 2008 NEC was changed to require listed handle ties or multipole breakers.
--
bud--

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Ok, thanks again. Lets add more to this now that I uncovered soemthing.
The present stove is on a 40A circuit. I was told newer stoves require a 60A circuit. Which means now I have to run a new 6/3 with a ground.
How many holes or notches are you permitted to drill through one joist? Is it better to drill several small holes , or one big hole?
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Avoid notches whenever possible - far more problematic. Your one big hole wouldn't be that big of a hole. If the one hole falls within the guidelines in that link I posted, you're fine. You won't be anywhere near the upper limit of allowable hole size, so I'm not quite sure why you're worrying. If you want to drill more holes that's not a problem unless you drill them to close together.
R
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I don't know anything about electric stoves. But NM (Romex or SER) #6 Cu has an ampacity of only 55 amps. Which means you can use a 60A breaker on it only if the load is rated at 55A or lower. If the stove is rated 60A, you need to use #4 Cu.
Cheers, Wayne
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Notches = NONE, holes that are spaced several times their diameter apart = Quite a few. -- Tom Horne
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I remeber reading that if curent to/from device is in one conduit, the EMF will not create induction heating. But your case will because at least one of your wires is sending in one conduit, and the return is in the other. I'm sure the bonafide electricians out there will clarify.
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Having a physical current loop will cause EMI and induction heating in any ferrous metal encircled by the loop. However, using a 12/3 cable for a MWBC does not create a current loop, all the conductors are routed together in the same cable.
Cheers, Wayne
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On 10/3/2010 7:20 PM, Mikepier wrote:

If you insist on drilling less holes, you'd be better off with a couple runs of 12/2/2. You'd have a proper neutral for every circuit that way. You have issues sharing neutrals with GFCI outlets.
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Steve Barker
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On 10/3/2010 9:40 PM, Steve Barker wrote:

But in this case the GFCIs don't know anything about the neutral being shared because they are connected downstream.
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