grounded

[grifftech]

  what is the thinnest wire I can use for grounding a 15 Amp outlet

[Monkeh]

I suggest you consult your local code or an electrician. Preferably the latter.

[SeanB]

The same diameter as the supply wire in most cases. It has to be capable of handling the fault current to trip the protective device in case of a fault.

[Cubdriver]

In the US, 14AWG is the thinnest you can use for supply and ground in a 15A branch circuit, though in practice the ground should be at least as large as the supply wiring so if 12AWG feeds the receptacle, a 12AWG ground conductor would be a wise choice as well.

-Pat

[German_EE]

Whatever your local electrical code requires.

[calexanian]

In the US, 14AWG is the thinnest you can use for supply and ground in a 15A branch circuit, though in practice the ground should be at least as large as the supply wiring so if 12AWG feeds the receptacle, a 12AWG ground conductor would be a wise choice as well.

-Pat

Correct. NEC specifies 14AWG copper conductor, however in practice nobody uses smaller than 12AWG because that is the standard Romex cable used in residential wiring. Typically that has a white sheath. It is common though for most houses to actually be run entirely in 10AWG which is typically yellow sheathed. What will happen typically with 14AWG is the series resistance of the cable at a specific length will create too much voltage drop.

[Cubdriver]

In the US, 14AWG is the thinnest you can use for supply and ground in a 15A branch circuit, though in practice the ground should be at least as large as the supply wiring so if 12AWG feeds the receptacle, a 12AWG ground conductor would be a wise choice as well.

-Pat

Correct. NEC specifies 14AWG copper conductor, however in practice nobody uses smaller than 12AWG because that is the standard Romex cable used in residential wiring. Typically that has a white sheath. It is common though for most houses to actually be run entirely in 10AWG which is typically yellow sheathed. What will happen typically with 14AWG is the series resistance of the cable at a specific length will create too much voltage drop.

Actually, I think #14 Romex has a white sheath, #12 yellow and I know #10 is orange.

-Pat

[calexanian]

In the US, 14AWG is the thinnest you can use for supply and ground in a 15A branch circuit, though in practice the ground should be at least as large as the supply wiring so if 12AWG feeds the receptacle, a 12AWG ground conductor would be a wise choice as well.

-Pat

Correct. NEC specifies 14AWG copper conductor, however in practice nobody uses smaller than 12AWG because that is the standard Romex cable used in residential wiring. Typically that has a white sheath. It is common though for most houses to actually be run entirely in 10AWG which is typically yellow sheathed. What will happen typically with 14AWG is the series resistance of the cable at a specific length will create too much voltage drop.

Actually, I think #14 Romex has a white sheath, #12 yellow and I know #10 is orange.

-Pat

I am sorry, you are correct. Too many work projects toasting my brain.

[Cubdriver]

I am sorry, you are correct. Too many work projects toasting my brain.

No worries; I know that feeling all too well.  I can't imagine wiring the whole house with #10 - I just did mine with #12 for all but the lighting circuits, which were done with #14, and the #12 gets brutal to splice after a while.  It's amazing how little movement it takes to work harden the ends of the wires and make them a bear to twist.  I got really tired of making pigtail splices in receptacle boxes!

-Pat

[Monkeh]

I am sorry, you are correct. Too many work projects toasting my brain.

No worries; I know that feeling all too well.  I can't imagine wiring the whole house with #10 - I just did mine with #12 for all but the lighting circuits, which were done with #14, and the #12 gets brutal to splice after a while.  It's amazing how little movement it takes to work harden the ends of the wires and make them a bear to twist.  I got really tired of making pigtail splices in receptacle boxes!

-Pat

Top tip: Don't use stupid connectors which require you to work harden the copper.

[crispy_tofu]

This isn't really contributing to the discussion, but I'd just like to warn the OP that 15 amps can cause pain and injuries. 

[Monkeh]

This isn't really contributing to the discussion, but I'd just like to warn the OP that 15 amps can cause pain and injuries. 

So can 50mA. He shouldn't play with it at all!

[bills]

I think the nec allows the ground to be 1 awg smaller for the ground IE: 14 ga for a 12 ga feed.
I could be wrong and would not surprise me, my info was from over 10 years ago.

[Monkeh]

I think the nec allows the ground to be 1 awg smaller for the ground IE: 14 ga for a 12 ga feed.
I could be wrong and would not surprise me, my info was from over 10 years ago.

That.. would be two gauges smaller. And very much the wrong way to arive at an appropriate conductor size..

[bills]

?? Please explain, are you saying a 16 ga. ground for a 12 ga. feed ?
bill

[Monkeh]

?? Please explain, are you saying a 16 ga. ground for a 12 ga. feed ?
bill

...

You know there are odd numbers too, right?

[bills]

Yes the standard awg we use are 16,14, 12 and 10 for household wire May be some 8awg.
our system uses 2 lines of 120-125 v and a common (neutral) the neutral and ground are connected together
for 220-250 v the two lines are used in series with the ground/ neutral connected together household wiring split the each of the 120v lines to half of the load or there about.
What am I missing? 
Now to be a smart ass what does AWG mean ?

[Monkeh]

What am I missing?

That between 12 and 14, you have 13, making 14AWG two gauges smaller than 12..

Now to be a smart ass what does AWG mean ?

Annoying Wire Gauge. Wait, no.. Awkward? Awful? Abysmal? Hang on, I think I've got it! American.

[bills]

  Yes your right
It is clear we sort of agree thanks for having a sense of humor.

[Monkeh]

I only wish my vocabulary at 6am could come up with more words beginning with A.

Oh, yes, asinine, that's a good, multipurpose word. Bit tinny though.

[bills]

 
Just to think 2 peoples separated by a language.

[Cubdriver]

I think the nec allows the ground to be 1 awg smaller for the ground IE: 14 ga for a 12 ga feed.
I could be wrong and would not surprise me, my info was from over 10 years ago.

I haven't looked at the code books in a while, but I believe that in 240V circuits (120-0-120) in the US, the NEC allows the neutral to be one or two sizes smaller (can't recall exactly) based on the reasoning that as long as the load isn't 100% on one of the 120V lines, the neutral current will be less than that in the lines because their opposite phase will cause the neutral currents to cancel one another, resulting in the neutral current being equal only to the difference in the current in the two lines.  Perhaps this is what you're thinking of?  As I recall, I was able to use 2/0 line and ground conductors, and a 1/0 neutral in the feed lines from my meter box to the breaker panel when installing my 200A service a few years ago.  I could look it up if anyone's interested.  And this of course is US electrical code I'm referring to.

-Pat

[bills]

I think we are in agreement that the grounds can be smaller the dis agreement is is in the awg wire sizes IE: 14/13 awg
our British friend thinks that we use all the awg sizes , but we skip the odd sizes. maybe we should use  the metric sizes
no I like the awg sizes. but we digress . 

[Monkeh]

I think we are in agreement that the grounds can be smaller the dis agreement is is in the awg wire sizes IE: 14/13 awg
our British friend thinks that we use all the awg sizes , but we skip the odd sizes. maybe we should the metric sizes
no I like the awg sizes. but we digress .

Well, they ARE all used. Just because they're not common in electrical wiring doesn't mean they don't exist! Sorry, I just can't call 14AWG one gauge down from 12AWG. One size down in common cabling, but not one guage!

As far as grounds being smaller.. sure. Hell, in all our standard cables (Romex equivalent), they are one size smaller in the smaller cables. 2.5mm² has a 1.5mm² CPC, 1.5mm² has 1mm².. 1mm² has 1mm² CPC though, as it's the smallest conductor allowed in fixed wiring. 4mm² actually has a 1.5mm² CPC, which is a problem. On longer circuits, the impedance is often too high to allow operation of a protective device in the required time (not an issue of the cable failing, but of preventing exposed metalwork being live for too long).

Which is why I say just jumping down a size is the wrong way to determine appropriate conductor size for ground.

[bills]

The question was can a smaller ground be used, Yes it can. would I do it NO! all the household and industrial wiring I have done I have used the same gauge wire for the ground as the line.
It makes no sense to use a smaller gauge although you can according to the nec?
It is just fun to argue with you all, but as electricians we have a duty not to stupid shit. we must make sure what we do is idiot proof .
I worked for UPS for last 25 years and my wiring never was a danger to any one.