Wire size vs. Breaker Size---Followup Question

This application is for a bedroom. I should also ask if I can use 15 AMP rated recepticles with 12 AWG cable on a 15 AMP arc-fault breaker.

Randell Tarin wrote:
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Yes. You can also use 15A receptacles on a general purpose branch circuit together with 12AWG and a 20 A breaker.

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#12 copper is rated for 20 amps. You are allowed to go down in amperage for a given wire size, so running #12 for a 15 amp circuit is perfectly fine, except for the fact that you are wasting your money doing so. Barring any extreme situations fo voltage drop, you should be fine using that as a 20 amp conductor as long as you don't mix in any # 14 in the circuit. Using 15 amp receptacles on a 20 amp circuit is O.K. too. Be sure that you "pigtail" your wire make-up, since a 20 amp circuit is generally not allowed to be "fed through" a 15 amp outlet, (except GFI's, and those that separately clamp two conductors under a torqued screw and plate).

Long Ranger wrote:
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Had the wire from a previous project. Wanted to use it and not have to run out and buy 14AWG, which would have indeed been a waste of money.

Long Ranger wrote:
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If you are using #12 there is no reason not to use a 20A breaker (unless you already bought the 15A ones.) The only limit on 15A receptacles on a 20A circuit is you can't have only a single receptacle connected. A duplex outlet is 2 receptacles.
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15A receptacles are rated 20A feedthrough and 20A total combined load from both outlets on a duplex receptacle. Since they are allowed on 20A circuits, they will be connected and used that way. The UL standard recognizes the likely usage.
-- bud--

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True enough if you look at the UL rating, but about 15 years ago or so the NEC sought to end the practice of "backwiring" outlets as a way of making up #12 wire. That is when manufacturers reduced the hole size on the back of devices so that a 12 would no longer fit. In doing so they made it kind of a "grey area" to use the side screws to carry the circuit through for #12 wire. (I'm sure the intent was for #12 on a 20 amp circuit.) That is why the backwire versions that incorporate a torqued plate have become so popular. Whan you use two wires under the same plate, the receptacle carries no feed through current. Anything more than two wires "should" be pigtailed if you want to be anywhere near proper about it. It is half-assed to rely on a device and it's terminations for the integrity of a circuit.

All of that being said and the 12 AWG being run, it would be better/best to have 20 AMP receptacles on a 20 AMP breaker....correct.
Is an Arc-Fault breaker for a bedroom overdoing it? I know it's now code, but really...
Long Ranger wrote:
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The typical 20 amp circuit utilizes 15 amp outlets unless there is a reason for a 20 amp. Probably unlikely in a bedroom, unless you are installing a wall air unit. Then it is advisable to give it a separate circuit anyway. You can apply a 20 amp circuit to 13 outlets, and a 15 amp circuit to 10 outlets assuming they are general purpose. The arc fault is required, so I would install it. I am suspicious of their effectiveness, and I really wonder if they aren't a way to jack the price up on home wiring so manufacturers have something new to produce. They typically go on a 2-wire circuit, although 3 wire versions are available. The three wire units I've seen are real pricey.

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Not at all. 15A & 20A receptacles are the same device, except for the additional right-angle slot on the 20A. As long as there is more than one receptacle, you can put 15A receptacles on a 20A circuit. They will carry the same current safely, and you can daisy chain either one on a 20A circuit. You can only put 15A receptacles on a 15A circuit, however.
Any UL Listed appliance that draws over 12A (1440W) up to16A (1920W) will have a 20A plug and won't fit in the15A receptacle. That will require a 20A receptacle on a 20A circuit, to insure that a single appliance doesn't load a circuit over 80%.
Ben Miller

Ben Miller wrote:
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A few code cycles back there were several proposals to change the prohibition of plugging in loads over 80% (may have been for 210.21-B-2).
One argument was that some UL listed devices, like hair dryers, with current draw of 12-15A can have 15A plugs - UL thinks plug-in devices at 100% are OK. (The CMP response was 'we are right, they are wrong'.)
(Another argument was that the 80% rule generally applies only to continuous loads in the NEC.)
-- bud--

wrote:
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These hair dryers are nowhere as big a load as they brag about. It is like air compressor stickers http://members.aol.com/gfretwell/hairdryer.jpg

snipped-for-privacy@aol.com wrote:
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I think the prudent measure would be to have everything rated at 20A. This is good insurance against whatever future energy hogs come on the scene.

| snipped-for-privacy@aol.com wrote:
|> wrote: |> |> |>>Ben Miller wrote: | |>>One argument was that some UL listed devices, like hair dryers, with |>>current draw of 12-15A can have 15A plugs - UL thinks plug-in devices at |>>100% are OK. (The CMP response was 'we are right, they are wrong'.) | | I think the prudent measure would be to have everything rated at 20A. | This is good insurance against whatever future energy hogs come on the | scene.
Like heating elements used as light sources?

snipped-for-privacy@ipal.net wrote:
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How else I'm I supposed to power my bedside rotissiere? Let's not forget the digital clock radio that doubles as a water bed/hot tub heater. ;-)
I'm just saying it's easier to prewire than rewire.

| snipped-for-privacy@ipal.net wrote: | |> | I think the prudent measure would be to have everything rated at 20A. |> | This is good insurance against whatever future energy hogs come on the |> | scene. |> |> Like heating elements used as light sources? | | | How else I'm I supposed to power my bedside rotissiere? Let's not | forget the digital clock radio that doubles as a water bed/hot tub | heater. ;-) | | I'm just saying it's easier to prewire than rewire.
I do agree. But I just hope we try better at avoiding energy hogs in the future. The typical home should never need more than 200A service and should do fine on even 100A. IMHO, if they want more than 48 kVA, they should be required to take a higher voltage or three phase to get it.
I'm all for charging commercial power rates for all residential power usage for the amount that exceeds the median for homes in that climate zone (determined county by county or city by city). That should help to discourage waste.

On 14 Mar 2007 19:47:43 GMT, snipped-for-privacy@ipal.net wrote:
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I am taking my lead from Al Gore. I may not be able to use the quarter of a gigawatt hour he uses in a year but I will do my best.

snipped-for-privacy@aol.com wrote:
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You need to go back to school to get your Doctorate of Hypocrisy degree before competing with him.
Ed

Long Ranger wrote:
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I have yet to see anyone who recommends backstab connections, and recommendations on newsgroups are commonly made to eliminate existing backstabs, especially for through wiring. (Not to imply you recommend them.)
20A side wired feedthrough is within the design and testing of receptacles and is commonly used. The only reason to have 2 screws is for feedthrough. I am not aware of significant problems and don't see how using feedthrough is "half-assed", particularly in residential.
"Torque plate" connections are nice and and are likely on spec grade devices that are higher quality overall.
-- bud--

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I agree, but let's differentiate between "backstabs" , which are bad news, and rear entry into clamping screws, which are OK.
Ben Miller

Ben Miller wrote:
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I think that's what he meant by 'torque plate', although I'm not familiar with that exact term.
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