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Forum topic by CudaDude posted 12-08-2012 02:43 PM 1386 views 0 times favorited 17 replies Add to Favorites Watch
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179 posts in 2278 days

12-08-2012 02:43 PM

Got the sub-panel installed in the garage with 60 amps running to it. Now I need to run a 15amp 220 for the unisaw. It’s a x5 3hp. What size wire should I use for this? 10 gauge?

-- Gary

17 replies so far

View bent's profile


311 posts in 3638 days

#1 posted 12-08-2012 02:48 PM

12 AWG would be fine. make sure it’s on a 20 amp breaker.

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3259 posts in 2645 days

#2 posted 12-08-2012 05:44 PM

Yeah I think you definitely need a 20 amp breaker so that means you definitley need 12 ga wire. Have fun!!

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179 posts in 2278 days

#3 posted 12-08-2012 05:55 PM

20 amp breaker is there just need to get the wire and outlet.

one more question. Does it matter how many 110v i run off a single gfi?

-- Gary

View John's profile


47 posts in 2043 days

#4 posted 12-08-2012 06:28 PM

The way I would approach this, in general, for any machine, is to look at the plate on the motor or machine case. It will tell you what the amp draw is for that item. Then add 20% for good measure, and that’s a reasonable minimum breaker size. Breaker size then determines the wire size you use. 15A = 14 ga, 20A = 12 ga. That saw is probably around 16A at 220v, so a 20A breaker should be fine, and 12 ga wire should be fine too unless you’ve got a long distance to go from the breaker panel.

No, it doesn’t really matter how many 110v outlets you run off a single gfi, within reason. Just as long as you aren’t pulling too much current through it. In a shop, though, the more circuits, the happier things tend to be, and I would suggest one circuit that’s dedicated to things with motors – in addition to the 220v for the table saw.

My small shop has two 20A gfci circuits. One is for tools, and the other is for the dust collector and lights.

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179 posts in 2278 days

#5 posted 12-08-2012 06:49 PM

don’t have far to go for table saw about 10 feet. Lights are still on the main breaker panel at the house. it’s a 125a sub panel, so I guess i have plenty of room for circuits. was planning on having the table saw circuit, a extra 220 which will never be used at the same time as the table saw, 2 circuits for 10 110v outlets one of which will be for d/c.

-- Gary

View EEngineer's profile


1102 posts in 3583 days

#6 posted 12-08-2012 07:20 PM

Does it matter how many 110v i run off a single gfi?

I actually ran into this this summer while wiring my garage shop. While we couldn’t find any limit specifically for GFI, the NEC does spec a limit to the number of outlets:

15A no more than 10 outlets
20A no more than 13 outlets

reference section 220.14, page 122 in the NEC 2011 Handbook

Check your local codes.

-- "Find out what you cannot do and then go do it!"

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774 posts in 2337 days

#7 posted 12-08-2012 07:39 PM

10-2 for the 220…table saw 12 for everything else your wiring a shop….not a house…size your breakers accordingly..


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2327 posts in 2397 days

#8 posted 12-08-2012 08:28 PM

For a 204 Volt connection, You should run #12 guage Three core wire. Which has Red connected to one breaker, Black to the other breaker, and White connected to the neutral bar.
Then the most important connection, which is the GROUND wire which is put there on purpose, to save your life, when all else fails.

-- Love thy neighbour as thyself

View CudaDude's profile


179 posts in 2278 days

#9 posted 12-08-2012 08:53 PM

Thanks for the advice Kunk, but I don’t have the extra $$ to hire an electrician, maybe the next time I see an air conditioning guy in the neighborhood I could slip him a $20 to come look at my handy work.

-- Gary

View Ted's profile


2838 posts in 2181 days

#10 posted 12-08-2012 09:06 PM

Kunk, if I were wiring a shop I would follow your advice to the letter. I like how you think. ;-)

-- You can collect dust or you can make dust. I choose to make it.

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37 posts in 2257 days

#11 posted 12-08-2012 10:20 PM

”2 circuits for 10 110v outlets one of which will be for d/c.”

I would suggest spreading your 110V outlets over 3 or 4 circuits, with one dedicated to the dust collector. Having multiple circuits would allow you to use a couple of high-current devices (heater and table saw?) simultaneously.

-- Peter

View EEngineer's profile


1102 posts in 3583 days

#12 posted 12-09-2012 06:22 PM

filling the cap

Oh, I just love statements like this! This is AC, not DC. AC, caps look like resistive load with a phase shift between current and voltage. There is no ‘filling the cap’ on AC circuits!

I call 1 hp 1Kw rather than the actual 747 watts.

Yep! AC motors have a significant Power Factor associated with them usually 0.75 TO 0.8. So although induction motors consume only about 750 W per HP, actual full-load current draw looks more like 1kW per HP. This is real current draw, resulting in real I^2 R losses and you have to account for it. I used to cite 750 W per HP until I looked into it more.

Now, to account for startup currents, the NEC specs additional ampacity for motor circuits. They spec 125% of full-load current carrying capability (FLA on the motor plate – you’ll find it is close to the 1kW per HP that kunk cites) for motor circuits. Multiply by 1.25 and you’ll actually be at about 1250 W per HP. Check your local codes but most are based on the NEC.

I don’t use extension cords in the shop at all. Never use a cut up extension cord.

I assume you mean never use an extension cord that has been cut up and patched. Google it. You’ll find that people are electrocuted every year due to patched extension cords. If I damage one in the shop, I cut it in half right then! But to never use extension cords? C’mon, that’s just not going to happen.

-- "Find out what you cannot do and then go do it!"

View runswithscissors's profile (online now)


2725 posts in 1994 days

#13 posted 12-10-2012 12:03 AM

According to the poop sheet that comes with the outlet, a GFCI will protect all ordinary outlets downstream from it. You can buy GFCI circuit breakers too, but they are pricey.
I see nothing wrong with cutting away the damaged portion of an extension cord and putting a new plug end on it.
If possible, I’d put in a dedicated 220 circuit for the DC. Even if you’re DC can be wired either 110 or 220, it will run more enthusiastically on 220. Such machines are usually rated at 1.5 hp, and some find them marginal for the heavy chip production from a planer. You get a lot more CFMs from a 2 hp DC, and they’re always rated at 220 (unless the manufacturer/importer is lying, which is sometimes the case, sadly).

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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179 posts in 2278 days

#14 posted 12-11-2012 03:38 PM

FWIW. The motor on the unisaw says it’s 12a peak.

does anyone know if the HF 2hp dust collector can / should be run on 220V so it’ll pull 10a instead of 20a?

-- Gary

View dhazelton's profile


2756 posts in 2266 days

#15 posted 12-11-2012 03:48 PM

Pick up one of the TimeLife or Home Depot books on wiring. They show every scenario most homeowners would ever have to encounter and diagram and explain hot to do the wiring, materials needed, max loads etc. Ten to twenty bucks well spent.

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