pinktoes

I read a book that said the same thing, so when I wired the second floor and basement of my house (long story - electricans did the main floor only), I used 12 guage (20 amp) wire throughout - just like the book said.

Now let me tell you why i would never do that again. Pulling the heavier guage wire - especially the 3 conductor 12/3 wire is a pain in the rump. It is also harder to cut the sheathing and splice. I did my work in the winter/spring and the wire was very tough to handle. You might find that driving eveything to 20 amps would have added expense that you really don't need to spend.

I think it would have been better to use more 15 amp (14 guage wire - white coating) circuits and load them less than use the 12 guage wire (yellow coating) that could handle more of a load. I do think there are some areas where overkill makes sense - but that is design dependent and should be worked through with your electrician.

In the end - it all worked out just fine. But after pulling nearly 3000 feet of 12/2 and 12/3 wire myself - I feel like it my duty to save others from the same thing. It was a load of work that could have been a lot easier had I not read that book! (the book did help me in other areas).

There was also one other thing that happened - an unintended consequence. Our electrical inspector (let's call him Adolf) did not like it that I used all 12 guage wire - even though it was way above code. You see - Adolf is lazy and he could not tell which circuits were 20 ampers becuase they had to be by code - or which were 20 ampers because I wanted it that way. All of the wire has a yellow coating - so he could not tell what was what. In the end, I had to label some of my wires in the attic and around the house so Adolf could trace it. With the 14 guage (white coating - 15 amps) and 12 guage (yellow coating - 20 amps), Adolf can see things more clearly.

You might want to think twice before specifying 20 amp circuits throughout. I would suggest thinking about your needs, where you might have haevier loads, and then specing 20 amp circuits based on those needs.

Just some suggestions - I am not a professsional electrician.

I much prefer the 20 amp circuits. Worth the expense and difficulty.

I would use twenty amp circuits throughout for receptacles and fifteen amp circuits for lighting. Possible excepton would be bedroooms because they must be on arc-fault circuits and it may take more circuits with arc fault breakers than necessary if you use twenty for receptacles and fifteen for lighting.

Do not use twenty amp devices, however. All fifteen amp receptacle devices are satisfactory.

There are a number of circuits that are required to be on twenty amp circuits to start with. Bythe time you do these, you've done one third of the house anyway.

I would use more 15 ampere circuits. One of the reasons being ease of wiring, but the main reason is that a 15 ampere circuit will trip much quicker than a 20 ampere circuit in a short circuit situation.
When you look at some of the cheap crap that gets plugged into a house circuit.( such as your grandmas antique lamp or that fan made in china) you want the quickest short circuit trip time that you can get.
If it is my house I run more 15 ampere circuits.
Now if you want to get into voltage drop calcs that is different. You may want to run 12 AWG but I would still protect it with a 15.
Just my opinion. Scott

I'm considering all your responses.

sbrn33: I could be persuaded to more 15s to keep amps as low as possible on any given circuit.

To ALL: What about using 100% copper rather than an CCAW? Any advantage?

"15 ampere circuit will trip much quicker than a 20 ampere circuit in a short circuit situation. "

The time for the magnetic trip in a beaker when a short circuit occurs is about the same no matter what the breaker rating.
The thermal trip will be activated at a lower level, but all the trip designs are based on percentage of overload.

I had to Google CCAW.

You CANNOT use aluminum wire for smaller branch circuits.

I sometimes use AL for range circuits, but not usually, and usually use it for sub-feeders.

I use mainly AL for services.

You won't regret having 20a general purpose receptacle circuits, but you might regret it if you have too many 15a circuits. It's not that much harder to work with #12, and it's worth it.

Petey's right about Copper Clad, but that's strange since at no
time (that I can find) was it ever implicated in causing fires.
Most devices that are listed for Cu also list Cu-Al too. And at
least one city (Tucson) makes an exception for it at # 12 and larger.

Table 310.5 Minimum size of conductors. REVISE Table to read:
Table 310.5
Voltage Rating of
Conductor - Volts
Minimum Conductor Size - AWG
0 through 2000
14 Copper
12 Copper-Clad Aluminum
8 Aluminum
2001 through 8000
8 8001 through 15000
2 15001 through 28000
1 28001 through 35000
1/0

While I absolutely agree that you should NOT use AL or CCAL on 15A and 20A circuits, I am not aware of any actual prohibition against its use in the NEC. As far as I can tell, 12 and 10 gauge AL and CCAL wire are still listed in the NEC as acceptable. Does anyone here who is declaring that it has been outlawed have an NEC reference stating that?

Add a new sentence to Article 310-5 to read as follows:. Aluminum and copper clad aluminum conductors smaller than No. 6 AWG shall not be used.

I found that as far back as 1999.

HTH
Chris

SaltCedar, where are you reading that from? The wording sounds like a proposal that was made for an addition to the Code, that was never actually approved. That limitation is not present in the 310.5 of the 2005 NEC, nor is it present in the draft 2008 NEC.

Pretty much ditto what baldwin hobo said on 15 vs 20, with the added caution of looking out for box fill requirements.

baldwin hobo and buzzsaw:

"Do not use twenty amp devices, however. All fifteen amp receptacle devices are satisfactory."

I thought you weren't supposed to put, say, a 15 amp wiring device on a 20 amp circuit because it won't carry the full 20 amps on down the line to the next device. Is that how it works? I guess it doesn't matter if you're careful not to install an 20s on down the line??

"SaltCedar, where are you reading that from?"

Dunno, it's adopted by AHJ's in several cities verbatim,
but you may be correct that it was proposed and never
adopted.

Regards
Chris

I thought you weren't supposed to put, say, a 15 amp wiring device on a 20 amp circuit because it won't carry the full 20 amps on down the line to the next device.

Actually the 15amp receptacles are rated for 20amp pass-thru. They just won't let you plug a 20amp device into them.

greg_h: Aha! Thanks.

i used to be in the camp of using all 20 amp... not that much more expensive... but its the work load that is killer.

i am in the middle of a bedroom remodel and am usinf 15AMP 14AWG circuts. i had to go 90 degeed through a rough cut 6x6 to get into the 1st floor stud cavity, then pull it up to the attic and distribute through out the room. 1 14-2 for recepticles and 14-3 for smoke/lights. both through a 3/4 in hole.

if i had uses 12AWG, that would have been even more hell than that i had to go through.

as it is i am looking to put an in wall heater, and will have to pull a 12AWG or even possibly 10AWG and am not looking forward to it.

new construction, MAYBE... but definatly not in a remodel.

I myself have done 2 20 amp circuits. Was gonna go with a 15 amp, but i usually exceed 15amps extremly easy. Glad i did it too. Living room and bedrooms i would go 15 amps and lights on 15 amps too. Basement and outside and kitchen areas i would do seperate 20 amp runs. Yes it does get hard to twist together and loop and whatnot especially after 3 #12 twisted together conductors.

I am getting ready to wire up the garage in my existing home. THey only had 14/2 wire on a 20 amp and only 2 plugs, thus when I used my saw with spot lights and the the pncake compressor would go off, so would the power.

I am going to run 12/3 from the main panel to the garage and the first 2-gang outlet then use 12/2 wire, one will be on 1 ciruit and the plug on another then I will go from there and onto the workbench with the three other sets of plugs. Plus I will be running a cable out there and cat5.

I'm just a DIY woth woodworking, thus I will not be setting up a big shop, I just want the right power to operate the new Tablesaw without having to worry.

QUESTIONS:
1) should I use 2 GFCI outlets in the first box or do a GFCI breaker instead? any preferences on brand?

2)should I use 20amp plugs in a different color such as grey so as not to have confusion with the 2 other 15 amp plugs (for future homeowners)

3) where online is a good electrical supply shop?

bumpo

Saltcedar are you here in Tucson?

Texas, why?

Regards
chris

Just because you mentioned a Tucson code amendment.........

Brian

The only thing I can tell you my city requires you use twenty amp breakers minimum period no exceptions never nuh-uh, and therefore you MUST use the 12 gauge wire. I do not know where else this is required, but it is required other places I have been told. We asked was this because of how gadget happy people are getting and were told no, it's fire hazard issues. Now you know as much as we do.

why would a locality require 20 amp for EVERYTHING???

i mean seriously, if you have a cct with just smoke alarms, that is waaaay overkill. even with a lighting cct... it would take alot of lights to max out that cct.