Wire and Circuit Size for 230V Shop Tools

I am about to start my wiring in my new workshop and was wondering what the proper wire size is for the Unisaw and I also have a 230V Dust Collector. Should I use 12/2, 10/2 or 8/2?
Also, anyone who has a unisaw 3HP, can you tell me what circuit size I will need?
thanks Craig Orput Camas WA
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It depends a little on how far you are from your load center (breaker panel). I'm fortunate, as mine is right there in my shop, as is my subpanel. If you have to go across half the house, go up a size regardless (in other words, forget about the 12 gauge feeder)
The 12 gauge wire is sufficient for a 20A circuit; you'd need 10 gauge for 30A.
A good argument can be made for running 10 gauge wire now while you have the best access. That way, if you ever do get one of those 5 HP machines, you'll have the capacity already in place. The difference in price for a 20A duplex breaker vs a 30A duplex breaker is negligible. The difference in wire costs will probably be on the order of 15 or 20%; insignificant compared to the cost/aggravation of wiring a new 30A circuit later.
Use the biggest boxes you can find for your receptacles because 10 gauge wire is a royal bitch to work with.
Also, although you mentioned two conductor wire, you may want to think about 10/3 in order to have both a ground (required in any event) and a neutral for future equipment that *might* require it.

Mine runs fine on a 20A circuit. Same with my 3 HP planer. See above for NB regarding distance from panel.
- - LRod
Master Woodbutcher and seasoned termite
Shamelessly whoring my website since 1999
http://www.woodbutcher.net
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wrote:

I believe you can go 100ft before having to worry about voltage drop, by NEC. That's half way across a really big house.

It's a good argument to wire a bit over in anticipation of future needs. Like LRod says - the difference in cost is really negligible.

Awe - 10ga is really not that bad. Big boxes are a good idea though. But geeze - don't scare the poor guy into thinking he's dealing with entrance cable. 10ga is a common find in house wiring and really is not that bad to work with.

Off the top of my head, I can't think of anything a home shop is going to use that would require 4 wire. But then again the reason my hair is so thin is from saying "off the top of my head..."
--

-Mike-
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Thanks for that correction Bob. I was not really sure, which is why I threw in the universal disclaimer "I believe". I've heard a lot of non-electricians make reference to this and even though I'd never read it in the NEC I just assumed that I missed it. Admittedly, I've never taken the NEC into the bathroom for really serious reading and read it cover to cover. It has always struck me as wrong simply because even in a modest sized house a branch circuit is very commonly a100 feet long. Hell - it does not take a lot to run out 100 feet of wire. But, I've been proven wrong enough times in my life to have learned to provide myself an out once in a while.
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The voltage drop issue is probably one of the most compelling reason to run a sub panel into your shop. Load diversity will tend to even out the load and the feeder can handle the start up current over the long haul distances. You machine drops stay short. Of course it also enhances expandibility and flexibility in the shop when you have a panel there. Put a lock on it and you have a way of securing the machines from curious kids.
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What are the amp requirements for the saw and the DC? You can certainly run one on a 20a circuit; the question is if you can run both. Probably, but check.
The second question is how far you are from the breaker box. If your load is close to capacity and you are far away, you will have to step up in wire size.
The third question is whether you will ever want to run anything else on this circuit; lights, air cleaner.
With that information, you can get an intelligent answer.
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I have my Unisaw and Grizzly G1029Z DC on a 30A circuit with no problems. Ran 10/2 wire, about 35ft. from the sub-panel to outlets.
DK Seattle,Wa.
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