What size electric wire do I need for a dedicated circuit to my 12 amp 220 table saw?

I'd use #12.

Agreed. 12 Gauge. 14 is is too close to the limits (80% of 15 amps is 12 amps and that is the max draw that you need). 12 gauge wire gives you a dedicated 20 amp circuit - appropriate for shops etc. While you are at it, just run 1-2 more home runs of 12 gauge to where you might need them later. The wire is pretty cheap as are the breakers.

Good luck!

Quote:

---

14 is is too close to the limits (80% of 15 amps is 12 amps and that is the max draw that you need)

---

Where are you getting this 80% figure from?
A 15A circuit can have a load of 15A. This is not a continuous load.
The only 80% limitation would be that since this saw is not fastened in place and is being plugged in.

Hi Stan,

The 80% rule has been in place for a long time. Here's one link: http://www.fs.fed.us/database/acad/e...sicdesigns.pdf

The NEC says:
Sections 220-3(a), 220-10(b), and 384-16(c). The NEC requires the branch circuit computed load for conductor sizing to be sized at 125% of the continuous load, plus the noncontinuous load (100%).

None of us know whether the OP will be using a continuous load or not. But why would one want to save literally like $2-4 and do it with 14 instead of 12 gauge? Sorry but that just doesn't make sense. Code aside - and his local code might well REQUIRE 12 (mine does) there are other things to consider:

Perhaps he will want to run more than one machine? Perhaps he will get a bigger table saw someday. Etc.

Bottom line - WHY would he wish to try and MAYBE save $2 or $3 today and later on have an issue and need another circuit. OR... possibly be code non-compliant TODAY?

Dedicated branch receptacle circuits should always be 20 amps. In many places this is code (true for me).

Very few local codes require #12 minimum. Also, I never questioned price, nor did I say I'd run #14. I was just questioning the blanket 80% rule you laid down. This is simply not so.

Just read what you wrote "....125% of the continuous load, plus the non-continuous load (100%)".
100% of the non-continuous load. A table saw is certainly a non-continuous load, so 100%, NOT 125%.

Yes, we are talking about #14 & #12. Small beans, but this blanket 125%/80% thing can get costly on some circuits, and usually for no good reason.
Would you size conductors for a 20HP 3-phase compressor motor at 100% or 125%? I think I know the answer and I bet I win the bid on that job.

" 12 gauge wire gives you a dedicated 20 amp circuit "

I know I pulled this out of context, but how exactly does 12 AWG wire give you a dedicated circuit?

The design of the circuit will do that, not the gauge of the conductor.

Also, we are all assuming that this is going to be a run with Copper conductors. What if the OP was considering AL conductors (Edison and Tesla forbid, say it isn't so) But if for some reason he was considering AL, then he would need 10 AWG conductors.

Quote:

---

Originally Posted by donf

" 12 gauge wire gives you a dedicated 20 amp circuit "

I know I pulled this out of context, but how exactly does 12 AWG wire give you a dedicated circuit? The design of the circuit will do that, not the gauge of the conductor.

---

It's from the OP's question. He wants a dedicated circuit for his table saw.

Even if he might be able to "get away with it", why would one install a new home run to a WORKSHOP... using a 15 instead of a 20? Sorry, but I stand by my recommendation.

Please understand, I take no issue with 12 AWG Copper conductors on a 20 Amp circuit. I even agree with the comment that a dedicated circuit is wise.

However, the dedicated circuit should only have the saw on it. Other receptacles should should be added to the room using a separate 20 amp circuit. But not the circuit that the saw is on.

Also, the 80% rule you are quoting does not apply to a dedicated circuit. However, if you set up a multi-outlet 20 amp circuit, that's where the 80% rule comes into being. It does not mean that you limit the supply amperage to 80%.

I does mean that you limit the connected load to 80% of the circuirt. In other words, the supply to the circuit is 20 Amps. The connected load side of the circuit should not be greater then 16 Amps.

Hi Don,

I think we're basically in agreement but saying different things. I always design my circuits to be both conservative and with an eye toward possible future needs. This is how I look at stuff, and it suits me.

I honestly do not care whether the 80% rule applies to a dedicated circuit or not. This is a very minor detail in this context. If "today's immediate need" EVER changes then the "pure fit 15 amp line" is very likely under-sized for future needs.

I stated right up front that I design things with the view toward potential future needs. If you guys want to nitpick one point (the 80%), without it's relationship to my design philosophy then this is merely a round robin and isn't a great use of time.

In any case, the OP has several answers, hasn't asked any follow-ups, or a "thanks, guys". So... I'm out on this.

Adios!

Funny how when someone doesn't like the fact that he is corrected on something as serious as the electrical code he calls it nitpicking.

I also right from the start said to run #12.

Quote:

---

Originally Posted by stanfortyman

Funny how when someone doesn't like the fact that he is corrected on something as serious as the electrical code he calls it nitpicking.

I also right from the start said to run #12.

---

Hey... isn't it FUNNY that the OP hasn't bothered to participate? :-)

I hereby acknowledge that the 80% rule does not apply to dedicated circuits, via the 2011 NEC.

Would anyone here actually design this with a mere 15 amp? Anyone? Beuller? Beuller?

Quote:

---

I hereby acknowledge that the 80% rule does not apply to dedicated circuits, via the 2011 NEC.

---

That was not the point, but forget it though. It's not worth it any more.

Quote:

---

Hey... isn't it FUNNY that the OP hasn't bothered to participate? :-)

---

Unfortunately this is extremely common.