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Old 02-19-2009, 01:29 PM   #1
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15 or 20 amp ?


I've been gradually rewiring my home over a few years. A few guys I know told me they did their whole house with 20 amp breakers and 12 gauge romex, the presumption being more is better.

So, for the most part I've done the same. Do you think maybe this is a macho waste of money? Also I've got a lot of 14/2 and 14/3 left over from old projects. Would it be in bad form if I changed out a 20amp breaker with a 15 and added on to a 12/2 circuit with the 14/2 ? I realize there's no danger in doing this but I thought it may confuse the next generations of owners.

What do you experts think? Thanks.

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Old 02-19-2009, 01:40 PM   #2
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15 or 20 amp ?


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I realize there's no danger in doing this but I thought it may confuse the next generations of owners.
Exactly.

It is considered bad practice to change wire sizes. Especially when the larger wire is at the feed end. Too much chance for someone to simply change the breaker back over to 20 thinking it is all #12.

I am in the camp that says "all #12" is just a macho thing. There is no reason to use #12 for lighting circuits in a residence. Unless of course this is a mcmansion that has super long circuit runs.


If you have to wire up 3&4 ways and dimmers with #12 you'll see what I mean.

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Old 02-19-2009, 01:42 PM   #3
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15 or 20 amp ?


It is kind of poor workmanship to extend a 12/2 with 14/2, but it's allowed if you change the breaker.
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Old 02-19-2009, 01:47 PM   #4
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15 or 20 amp ?


I use #12 for outlet circuits, AC runs, fridge
I use #14 for lighting circuits

I've never run #14 off of #12 & installed a 15a
Too much chance of someone down the road seeing the 20g in the panel & putting in a 20a breaker

I do have #12 on the 2nd floor between 3 can lights
I had a lot of wire & hadn't bought any (back in 05), had paid $29
Then I went to buy more & #12 was up to $99 for 250'
So the feed is #14g from the panel
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Old 02-19-2009, 02:09 PM   #5
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15 or 20 amp ?


Speedy,

I have done a number of 3 ways and dimmers with 12 and you don't have to tell me, it's a PIA. (but it gets easier with experience)
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Old 02-19-2009, 02:16 PM   #6
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15 or 20 amp ?


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Originally Posted by handifoot View Post
(but it gets easier with experience)
...but no less annoying.
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Old 02-19-2009, 02:31 PM   #7
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15 or 20 amp ?


Box fill is another reason I stick with #14 for lights
Seems like I split off more for lights & smokes then I do for outlets
Plus I use 14-3, but never really use 12-3 - due to AFCI now
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Old 02-19-2009, 04:32 PM   #8
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15 or 20 amp ?


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Unless of course this is a mcmansion that has super long circuit runs.

Most "mcmansions" have sub panels everywhere. Maybe a 1000 amp service...probably all 10 awg.
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Old 02-19-2009, 06:31 PM   #9
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15 or 20 amp ?


20 amp for kit/micro/appliances/bath.

15 amps for lighting general receps.

I'd run a 20 to a garage or an outside recep where I might want to plug in outdoor power tools.

I never trip breakers in my house.

I did one time add so many track lights at a house that the 15A lighting circuit tripped. Guy was an art collector and wanted every painting in the living room lit.

I think I installed about 30 or 40, 50 watt lv halogen fixtures in a 15x15 room, all painted gold to match the gold leafed ceiling.

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Old 02-20-2009, 07:17 AM   #10
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15 or 20 amp ?


Historically there has never been "enough" with home wiring. There are never enough outlets. Not enough circuits. Not enough spare slots in the breaker panel. Not enough amperage at the main panel. Etc.

It has been tradition with home wiring to only install what is needed today and to not think about tomorrow.

This is like a barber who leaves your hair a little longer than you want it. Good business! You will be back for another haircut sooner!

With that said, for my house all 120V circuits are 12 ga. 20 amp circuits. This includes the lighting circuits. And I have about 10 spare slots in the breaker panel.

So plenty of "extra" capacity built in! I can easily add something to one of those lighting circuits and the capacity is there already.

I designed and installed all the wiring in my house about 8 years ago. It is amazing all the new different things I have now which I had no idea I would have 8 years ago. But this is the way it has been with homes in the past. As time goes on, you add more rooms, gizmos, whatever...

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