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Forum topic by CharlesA posted 12-25-2015 12:13 AM 669 views 1 time favorited 17 replies Add to Favorites Watch
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CharlesA

3022 posts in 1263 days


12-25-2015 12:13 AM

I just wanted to confirm that tools that require single phase 220 and those that are low voltage 3 phase 220 would require separate electrical feeds. Am I correct?

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson


17 replies so far

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TopamaxSurvivor

17671 posts in 3141 days


#1 posted 12-25-2015 12:16 AM

You could use 2 legs of a 3 phase circuit for a single phase application if it were sized and protected appropriately.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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CharlesA

3022 posts in 1263 days


#2 posted 12-25-2015 12:20 AM

Thanks. That’s what I needed to know.

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

View MrUnix's profile

MrUnix

4233 posts in 1664 days


#3 posted 12-25-2015 12:20 AM


I just wanted to confirm that tools that require single phase 220 and those that are low voltage 3 phase 220 would require separate electrical feeds. Am I correct?

- CharlesA

Not sure exactly what you are asking… but I believe you are questioning if you need something other than 240v single phase depending on machine? If so, then no… single phase 240v can be used for either single or three phase machine, although you need a phase converter between the supply and motor for three phase. One 240v single phase wall plug can be used for either. Was that what you were looking for?

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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TopamaxSurvivor

17671 posts in 3141 days


#4 posted 12-25-2015 12:20 AM

U R welcome, Merry Christmas ;-)

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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CharlesA

3022 posts in 1263 days


#5 posted 12-25-2015 12:27 AM

Thanks, Brad. Let me be clearer and perhaps you and Bob can set me straight.

I have all 110v tools now and only 110v power. I was fantasizing about buying this used Delta/Milwaukee cabinet saw off of CL—it is 220 3 phase. I can’t imagine I’d buy another 3 phase tool. So, if I had this 3 phase tool and a single phase 220 tool that I might buy in the future, would I need to install two 220 lines, one for any single phase machines and one for the 3 phase.

What I hear Brad saying is that it could be one line with a single phase outlet with a second outlet that would have a phase converter for the 3 phase. If that second tool was a dust collector that would be run at the same time, could both outlets still be on a single line (assuming I had enough amperage capacity)?

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

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MrUnix

4233 posts in 1664 days


#6 posted 12-25-2015 12:39 AM

In that example, I believe code would dictate two 240v single phase circuits… one for the saw, the other for your dust collector (or whaever other tool you want to run at the same time). It doesn’t matter if the machine is single or three phase being plugged in. For the three phase machine, you just need a phase converter between the outlet and the motor of the machine – it takes single phase 240v input, which is what you will have at the wall. Having both off the same circuit is doable, but not to code AFAIK.

As for getting 240v single phase by using two of the three legs in a three phase system, I’ll take Bob at his word on it, but I can’t see how that would work as they are 120/240 degrees out of phase and you should only see ~208v between legs. But that discussion is for another time and day and three phase stuff always screwed me up in college :)

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View AZWoody's profile

AZWoody

697 posts in 689 days


#7 posted 12-25-2015 12:47 AM

As long as you’re going to just run one tool at a time, 1 circuit should be fine.

I have 3 circuits in my shop but for a little separation and convenience. One is for the dust collector, 1 runs along 1 wall and runs 3 machines and 1 along another wall that runs 1 machine.

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TopamaxSurvivor

17671 posts in 3141 days


#8 posted 12-25-2015 12:47 AM

Trust me, it works ;-) The only issue would be having a 1.15 or higher service factor on the single phase 230 v motor running on 208.

I was thinking you wanted to plug in a single phase motor to a 3 phase circuit. Running both simultaneously would require 2 circuits. You could run one circuit that would be called a “feeder,” then tap off, but each motor/ outlet would require fuse protection. You probably do not want to got there is a small shop.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View MatthewG's profile

MatthewG

74 posts in 2244 days


#9 posted 12-25-2015 01:30 AM

The short answer to your question—assuming you live in the USA:
—If you have 120VAC to your shop, you can run 120V tools.
—If you have 240V service, you can run 120V tools and 240V tools.
—If you have three phase power, you can run 120V, 240V,and three phase tools.

If you don’t have three phase service (a look inside the breaker box will tell you), then you can generate three phase power from 240V power with a phase converter. The phase converter is just an “adapter” between the 240V wall plug and the three phase tool.

The longer explanation is below.

==========================

Tools that are “120VAC” have two wires to carry the current that delivers power and (sometimes) a third wire for ground. The ground wire does not normally carry current. The two power wires are typically HOT and NEUTRAL, with the HOT at 120V compared to the ground and the NEUTRAL at 0V compared to the ground. If you plug the red lead of an AC voltmeter into the smaller slot in a 120V plug, and the black lead to ground, you should see 120V. The larger slot should show (close to) zero volts compared to ground.

Tools that are “240VAC” have two wires carrying power and (almost always) a third wire for ground. The two power wires are both 120V compared to ground, but they are “out of phase” or have opposite polarity with each other, so the two voltages add together to get 240V. In a 240VAC wall plug, a voltmeter should show 120V on either slot compared to ground, and 240V between the two slots.

Three phase power has three wires carrying power, and a fourth wire for ground. However, there are many different ways to connect the neutral. The ground is almost always connected to the neutral near the transformer or power lines coming into the building.

The diagram below is one common arrangement, which may be the way your building would be hooked up. (I grew up in a cabinet shop in rural Iowa—it was wired this way.) The ground wires are not shown.

Some of the 120V AC plugs are connected between PHASE A and NEUTRAL. The rest of the 120V plugs are connected between PHASE C and NEUTRAL. Note that PHASE B cannot be used for 120V plugs; the voltage compared to NEUTRAL is too high.

The 240V plugs can be connected between any two phases (A and B, B and C, or C and A.)

The three phase plugs use all three phases, plus a ground. Diagrams like this almost always draw the three phases in a triangle, because the three voltages form a triangle—they are separated by 120 degrees.

==================================

If you have any doubts on how this works, call an qualified electrician. Hope this helps—let me know! Thanks.

-- Matthew, from beautiful Wisconsin USA

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Ger21

1047 posts in 2596 days


#10 posted 12-25-2015 01:56 AM

If you buy a 3 phase saw, you might be better off buying a VFD to run the motor, rather than a phase converter.

-- Gerry, http://www.thecncwoodworker.com/index.html http://www.jointcam.com

View MrUnix's profile

MrUnix

4233 posts in 1664 days


#11 posted 12-25-2015 01:58 AM


If you buy a 3 phase saw, you might be better off buying a VFD to run the motor, rather than a phase converter.
- Ger21

A VFD is a phase converter when used with single phase input.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View CharlesA's profile

CharlesA

3022 posts in 1263 days


#12 posted 12-25-2015 02:44 AM

Thanks, everyone. You convinced me to pass up on the three phase machine.

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

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MrUnix

4233 posts in 1664 days


#13 posted 12-25-2015 02:56 AM


Thanks, everyone. You convinced me to pass up on the three phase machine.

- CharlesA

Noooo!!! How come?

That three phase saw would be superior to a single phase one – more bullet proof and a lot of extra features you just can’t get with a single phase machine!

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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CharlesA

3022 posts in 1263 days


#14 posted 12-25-2015 03:00 AM

Several reasons: 1) i looked at the ad again and discovered the saw is 100 miles away—I’m not really sure about the condition of the saw—I’m not up for a restoration, 2) The saw no longer has its fence, 3) I would end up spending $500+ on the wiring, converter, etc., 4) Not sure I have room for it anyway.

In case any of you want to buy it
http://louisville.craigslist.org/tls/5331134042.html

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

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MrUnix

4233 posts in 1664 days


#15 posted 12-25-2015 03:14 AM

Wow… that is a Delta 12/14 beastie.. it does look like it would take a bit of work to get it up to speed – but those are incredible machines and don’t come up for sale very often. At least your reason for passing on it isn’t strictly because it’s three phase :)

Shame it’s so far away – I would love to go see it in person and perhaps bring it home with me. With a little love, it would make a fantastic work horse. Here is one that’s been restored:

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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