Except for money saving is there any reason why you would not put 20 amp wiring and 20 amp GFCI receptacle (=1 per circuit) everywhere?

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    Related: diy.stackexchange.com/questions/75011/… – user56530 Jul 17 '17 at 19:08
  • Fridges and freezers should not be on a GFCI for food-safety reasons. – mmathis Jul 17 '17 at 19:25
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    @mmathis better check your code book on GFCI requirements NEC 210.8. If within 6' from a sink or in the garage they are required. My state exempts them for dedicated equipment not easily moved, but many do not. – Ed Beal Jul 17 '17 at 22:39
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    @EdBeal then don't locate your fridge or freezer in the garage or within 6' of the sink – mmathis Jul 18 '17 at 0:18
  • Most homes do have a freezer in the garage and many apartments have there fridge within 6'. – Ed Beal Jul 18 '17 at 18:23

It's wasteful.

I realize that most folks think with their wallets and not much further, but #12 wire contains 59% more copper than #14 (source). That's (nominally) 59% more energy wasted and pollution created in mining, 59% more chemical pollution from refinement, and 59% more weight to lug around as you work.

It's also much less pleasant to work with in a box, and fills boxes and nuts much quicker in terms of legal capacities.

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    Your logic about extra weight makes no sense, you are reasoning that you can carry only 14AWG. That is untrue, too many circuits require 12AWG so you condemned yourself to carrying both. That second spool is an average of half full, so that's 250' extra of wire that is permanently in your inventory, it had to be manufactured with all that badness you claim. Difficulty of working in a box also depends on your craft, I'm 99% in conduit with stranded. Easy peasy. I hate solid wire of any size. – Harper - Reinstate Monica Jul 17 '17 at 21:56
  • I wasn't referring to the weight in a truck. I was referring to carrying it into the building and pulling it. – isherwood Jul 18 '17 at 2:46
  • Carrying both is not a problem. If you're roping houses it's common. Any wire you carry is only permanently in your inventory if you stop working. – Spark Jul 18 '17 at 17:09
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    @Spark I think he means literally carrying around on your shoulder, not carrying in inventory. As in, #12 physically weighs more than #14, so by using only #12, you're lugging more weight around. – Chris M. Jul 18 '17 at 18:29
  • I wasn't clear when I said "Carrying both is not..." I meant carrying both in your inventory. Which is what I think he was referring to. However, if I'm wrong it wouldn't be the first time. It wouldn't even be the first time today! – Spark Jul 18 '17 at 18:51

Using 12AWG everywhere is exactly what I do. As far as waste of materials, the real waste would be owning twice as many spools of wire, everything in two sizes, the money tied up, the wire just sitting around, all that manufacturing totally unnecessary. Grabbing the wrong spool and inadvertently doing unsafe work, etc. And for what? So you can have more nuisance trips, and prevent people from using 20A appliances?

Oh, there's another neat trick I can do. If I have to cram more than 9 wires into a conduit, I can just do it, and use 15A breakers to comply with the conduit fill rules. Other than that I don't stock 15A breakers.

As far as GFCI outlets everywhere, just use one GFCI per circuit, using the LOAD terminals correctly. For circuits where you don't want load X knocking out load Y, it's fine to split the circuit before the "LINE" terminals, so you have two GFCIs protecting two separate zones on the same circuit. Just don't wire them nose to tail or you'll play a "Yo Dawg" joke on yourself.

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  • Seems to me that you'd stock the same number of spools of wire--half in each size. What's needed in two sizes? Staples and nuts cross over. Panel and device connections are cross-compatible for the most part. Have you ever actually left unsafe work that was or wasn't caught by an inspector or your own team? This all seems like a hyperbolic argument in favor of laziness. – isherwood Jul 17 '17 at 21:40
  • Also, I don't think that the OP was suggesting that every box contain a GFCI outlet. That's quite a leap of logic on a reader's part. – isherwood Jul 17 '17 at 21:41
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    Yes, I think he did mean that. I do not understand how you expect me to install both 12AWG wire and 14AWG wire without owning spools of both sizes. (In my country I am required to use 12AWG on some circuits, so going all-14 is out of the question). Stocking half as many spools of each, how does that work, stock 12/2 14/3 12/4? In THHN the multiple colors have a purpose. You can call it laziness if you like, I call it "standards of practice" LOL. – Harper - Reinstate Monica Jul 17 '17 at 22:33
  • I use 12 on most circuits but still keep 14 arround. I thought the OP wanted GFCI everywhere, I have seen just that and was called because they kept tripping. Down to 1 on each circuit the problem went away. – Ed Beal Jul 17 '17 at 22:44
  • My sister's extremely well made small house built 2005 had all 120 V circuits for lighting and receptacles protected by 20 A breakers so I assume they used 12 AWG Cu. My own house (1970) had the 120 V circuits wired in Al 12 AWG for 15 A and 10 AWG for 20 A breakers. When I pigtailed the receptacles I used 12 AWG Cu for all receptacles because I thought three #12 wires in a red Scotchlok would give a better connection than two #12 Al and one #14 Cu (overthinking?). I pigtailed the 15 A switches and light fixtures with #14 Cu--was that ever easier to work with than #12 Cu! – Jim Stewart Jul 17 '17 at 23:16

It seems you have poked a hornet's nest.

I use and advocate 20 amp circuits for receptacles and 15 amps for lighting.

Recently, with LED lighting, lighting circuits draw much less than they used to. 15 amps is usually plenty.

20 amp receptacles are not required on 20 amp circuits unless you have a very high current draw piece of equipment.

The only cost difference is the wire.

As others have said #12 solid is more difficult to work with in switch boxes but it is worth it for receptacle circuits because of the extra ampacity.

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Is there a reason not to use 12 other than cost. Waste has been raised as a possibility. I have found the need to replace a lot of #14 wire in the past but rarely need to replace #12 an AC unit is the one place that I have needed to upgrade #12. I have wired several homes with #10 (what the owner specified). To try and answer the question I would say wiring with all # 12 and not using 14 is fine and done on many high end homes as a selling feature. To answer the GFCI question only 1 is needed to protect the entire circuit, multiple GFCI'S may cause false trips I have seen this more than a few times. Since the question has been updated I will add that multiple GFCI's can cause false trips especially when testing a device that is fed from a GFCI.

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  • The OP's question was edited Jul 25 to clarify the intent to have one GFCI per branch. – Upnorth Aug 22 '17 at 12:32

I believe it's a preference. Originally (1960's) there were only three required 20A circuits in a single family dwelling. 2 small appliance and 1 washer receptacles. Over time other circuits are added 1 for bathrooms, we always installed a 20A for the newer microwave due to increased loads, also larger and more sophisticated dishwashers, disposals and refrigerators. So you may wind up with 6 or 7 20A breakers. Now most of the work I have done in the past is commercial and industrial so we always run a 20A circuit as minimum. Any house I have done were strictly high value custom homes so we always just installed 20A circuits. And I am not really interested in any arguments whether it is right or wrong.

On the second part of your question. There is really no need to run GFCI circuits throughout the whole house since the 2014 NEC now requires all outlets to be AFCI protected anyway. There are differences between Ground Fault and Arc Fault but both are used to prevent shock and burn hazards. So at this time the idea of extra protection by adding GFCI's is not necessary. Just follow the NEC on new construction or upgrade to the most recent NEC.

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    And I am not really interested in any arguments whether it is right or wrong. but this is the OP's question. Kind of a non-answer in that case... – mmathis Jul 17 '17 at 21:30
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    Yes, it is a matter of preference, but you haven't explained why all #12 is yours. – isherwood Jul 17 '17 at 21:42
  • Actually, GFCI and AFCI have two totally different purposes. GFCI is to protect personal from shock hazards. AFCI is to stop non-working arcs from starting fires. – ArchonOSX Jul 18 '17 at 15:56
  • @mmathis and isherwood - I have not explained why it's a matter of preference because it's a stupid argument. It simply means if you want to you can and if you don't want to you then don't. – Retired Master Electrician Jul 18 '17 at 19:24
  • @ArchonOSX - "There are differences between Ground Fault and Arc Fault but both are used to prevent shock and burn hazards." – Retired Master Electrician Jul 18 '17 at 19:26

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