Many questions on residential wiring, any help appreciated

[ltrmc02]

New to your site here, hello to all.  Hoping to find some black and white answers.  I work in automated controls at a pharmaceutical plant, I'm not an electrician but understand electricity so I was interested in wiring my new construction house that I'm currently in the process of rough-ins.  I have asked different electricans and the county inspectors several questions and many times get different answers so I'm left uncertain of some things.

First question no one has really given me an answer to is I wanted to know if there are certain areas of the structure that can't be drilled through by code and a bit size limit?  I've heard you can't go through LVL's and I've read that wire needs to be stapled at least 1.25" from the edge of any joist?

Next I have a copy of the 2005 NEC, I know I need a 2008 but don't know if I can afford the lawyer to decipher it for me LOL.  Looking at table 210.24 it lead me to believe you can tie a light and switch run on 14ga wire to a 20 amp circuit supplying other lights and receptacles run on 12ga wire, is this correct?  I asked an inspector this question and he said yes but then your lights would be AFCI protected if on an outlet circuit, I thought that lights as well as plug outlets 15&20 amp had to be AFCI protected except bathrooms, kitchen, outside and garage and those had to be GFCI protected? Can someone confirm or correct my thinking here?

I've installed a 400amp meter base splitting to two 200amp exterior panels and planning on feeding a 200 amp panel in the house so I won't have to go outside to reset those AFCI breakers LOL.  I was told by the supply house that a 4\0 SCR wouldn't be allowed as they lowered the current rating for this in 2008 but I can use two 4\0 single cables inside a conduit to run the power and that will be rated for 200amps, he said he couldn't figure out why they implemented this.  Is this statement true?  I will need to run under the house with this approx 12ft so will two 4\0 for power and a 2\0 neutral work in conduit, forgot what size ground he said I'd need in the conduit as well.

Had someone tell me that all outlets had to be a certain childproof style now is that correct?

I'm sure I'll have more questions and I really appreciate anyone for taking their time to guide me straight on these questions.  Hopefully I can help someone else out once I figure it out myself LOL.  Hope you all are doing well.

[ltrmc02]

OK, after more studying I see that many municipalities don't follow every aspect of the 2008 code and some have their own regulations so I'll check with the county in the morning to see what I'd fall under.  I'm in NC, Johnston County.

[JP]

Let me start off my letting you know that the local Authority having jurisdiction in your area is the final judge and jury regardless of what the national code states, and every area is different.

1)   I believe you are correct about drilling from the edge of the joist, what you can and can’t drill through is more of a local building code thing. Obviously you don’t want to drill in a way that could structurally damage your home.

2)   I can’t remember off hand if the 2008 code allows you to tap off with a 14g wire on a 20amp circuit but I don’t think so. My rule of thumb has always been 20amp circuit 12g wire.

3)   You are right about the AFCI and GFCI protection in the 2008 code, if your area has adopted it.

4)   The feed for your panels could be done in SCR or pipe, SCR is aluminum so 4/0 would be required. However if you do it in pipe you could use 3/0 copper.  http://www.wireityourself.com/wire_sizes.html

5)   2008 NEC 406.11 Tamper-Resistant Receptacles in Dwelling Units.
In all areas specified in 210.52, all 125-volt, 15- and 20-ampere receptacles shall be listed tamper-resistant receptacles.If the 2008 NEC is in effect in your area, yes, the receptacles should be the tamper-resistant types being installed.

Hope it helps!

[ltrmc02]

Thanks for the reply JP.  I was told by the local electrical supply house that 4/0 SCR couldn't be used to carry 200amp any more under the 2008 code but 4/0 aluminum if you buy it as single conductor wire and run it in conduit is allowed to carry 200amps, don't know if I was told wrong, just didn't sound right but the man telling me said it didn't make sense to him either so I just don't know?

[JP]

Don't remember seeing anything about that in the 2008 code, I'll do some checking and let you know.Supply houses are usually for parts, I have never been to one where the employees know the code.

[ltrmc02]

Thanks for the feed back JP.  Another question I have is would it be more cost effective to run 14ga wire and have more AFCI breakers or 12ga and pay more for the wire?  I have a fairly long house layout so some of my runs from the panel just to get to the first receptacle or switch will be 50ft.  1 story house, thinking of putting a sub panel in the attic for future use.

I have been studying some wiring books and seeing that many circuits tie in receptacles and lights together but a few electricans I have spoke to seem to like to separate lighting and outlet circuits, any good reasons for not combining them?

[JP]

If cost is a consideration than do it the least expensive way that still meets code.  Make sure placing a sub panel in an attic meets code in your area, heat buildup, spacing and such things may not meet code.

As far as separating lights and receptacles, future troubleshooting is a big reason, plus it keeps circuits better organized. You would also have the advantage of still having light if a receptacle circuit trips. Remember, you will have to live with the way you wire your new house; the better organized and the more separated your circuits are will be of future benefit. For example if you have not already considered running more than the required circuits to your kitchen countertop you may want to depending on how you use your kitchen. Small countertop stuff like fryers can really add up if multiple items are used, I’ve seen some draw 15 amps alone. I’d recommend multiple 20 amp circuits for the kitchen countertop, at least 2 20 amp circuits for the bathroom for the hair dryer, curling iron angle. And also consider 20 amp circuits for where a vacuum would be plugged in. Items like these can easily draw close to 15 amps and since the current draw should only be 80% a 15 amp circuit will not suffice.