06:38AM | 09/25/06
Member Since: 09/24/06
5 lifetime posts
Hello all, I am having a hard time finding some information about residential new construction wiring (California).

I am building my own home and running all my own electrical. My service entrance is on the end of my garage and my Bedrooms are the furthest they can be from that point...

My distance from service to the very last plug in my master bathroom may be as far as 140 to 160 feet away. This will be a 110v 20amp circuit. I also have another bathroom and a bedroom that will be 100-140 feet from my service. I plan on running 12/3 throughout my entire house.

My questions are -

1. On these long runs, will 12/3 suffice or should i be running a 10/3 or?

2. Also can anyone point me to a good reference web site for the home builder/electrician?

3. Can my lights/fans in these rooms be powered on the same circuit as the wall plugs, or do i have to run separate lighting circuits?



07:11AM | 09/25/06
Member Since: 04/25/05
1916 lifetime posts
"I plan on running 12-3 through the house".

Unless you are talking about running multi-wire circuits you will want to use 12-2 cable.

My convention the ground wire is also assumed and is not list. Thus 12-2 consists of a black, white, and bare ground wire.

A house like yours is idea for using a sup-panel near the bedrooms.

The NEC allows any mix of receiptacles and lighting fixture on a circuit. However, some local admendments might limit this.

For convience if you are paints, replacign a light or receptacle, etc I prefer to keep the lights on a separate circuits.


07:19AM | 09/25/06
Member Since: 09/24/06
5 lifetime posts
you are right about the 12/2, that is what i want to use, i miss qrote. Thanks for that reminder.

As far as the sub pannel goes, i am beyond the point where a subpannel will work. In hind sight i should have put a sub pannel on my garage/house wall cutting off about 60' from my long runs. I dont think that is a good option now, there really is not a location that would be acception to place a sub pannel.

Do you think that a sub pannel is my only option for these long runs? I have no problem, other than it is going to cost me, to run 10/2 all the way to these distance rooms, then run 12/2 after the first plug. I dont want to under rate anything and would much rather run thicker guage if needed.

I was told i can get away with 12/2 up to 100' but want further opinions.

Thanks again.


08:14AM | 09/25/06
Member Since: 04/25/05
1916 lifetime posts

That 3% is fairly restrictive. You could go to 5%. But watch any circuit that will have a heavy load (heater, including hair driers; motors; laser printer).

And by keeping receptacle loads off of lighting you won't see flicker when you run the vac, etc.

For the light you might want to design for a max of 10 amp and use a 15 amp breaker. Taht is easy to do with lighting as you know the max size of bulbs that each will take.

But I am questioning your number for the distance. AS I read it that is LENGTH of the cable run. And that is how those two calculators are setup. 160 ft is a very, very, very long run in a house.

But if you go do raw calculations you need to use the CIRCUIT LENGTH, which is twice the cable lenght as you have both the supply and return wires.


A sub-panel can get into any place that is wide enough for clearnace and not in a bathroom or clothes closet.

Hallway, bedroom. You can hange a picture over it or put it behind a door (but check with you local building inspector before you put it behind a door).


09:16AM | 09/25/06
Member Since: 09/24/06
5 lifetime posts
I am figuring my length from pannel to last outlet. garage is 40 feet, over great room (20'), to master bath (50'), down walls and to last plug (about 30')


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