The difference between single and 3-phase

[sjeff70]

Okay, I give up.  After spending over an hour searching through threads and googling, trying to find out which I should be looking for.  

Finishing my basement, I'll be running a dedicated, 240v line.  Should I be looking for single or 3-phase machines?  I cannot believe how complicated it is trying to find out which I need for a 240v outlet!

[Eric.]

You want single phase unless you live in an industrial building.

[wdwerker]

3 phase is commercial power, there are 3 hot legs and one neutral. Imagine 3 garden hoses spraying on a fan from 3 equidistant points around a circle, 120 degrees apart.

240 volt Residential power is 2 phase, 2 hoses spraying the fan from 2 points 180 degrees apart. All the different outlets are for different code requirements in different situations. A lot of the differences are the amperage required by each machine.

2 hot legs, 1 neutral leg and maybe a ground leg in some situations.

120 volt is one side of the 240 hot legs and a neutral plus a ground.

[atlinwi202]

240 volt residential is still single phase. There is no 2 phase. You are correct that it would have 2 hot wires though.

[Trip]

Residential power is typically supplied as dual/split phase – the term 2-phase is discouraged. Industrial power is typically supplied as three-phase. Note: there are exceptions, but they are out of scope. The technical difference between 1p and 3p really doesn't matter for the hobby woodworker. 

 

99.99% of hobby/small-shop woodworkers can ignore 3p. If you intend to source the kind of kit you see at Home Depot, Woodcraft, Rockler, etc and/or discussed by 99.99% of the threads on this forum, then you don’t need to even think about 3p (other to know that it exists and you can't plug a single-phase tool into a 3p outlet and vice-versa*). There are several members on this forum with 3p shops, but I bet it's under ten...

 

However, if you are interested in restoring vintage pattern kit and/or intend to use large stationary tools (14” table saw, 16” jointer, 24” planer, wide-belt sander, etc), then you need to know about 3p and its implications for your shop... and invest in a forklift...

 

As a rule of thumb, woodworking tools with electric motors up to 5HP are single/split-phase. Woodworking tools with motors above 5HP are generally three-phase. There are exceptions, but the inflection point is about 5HP -- the reason is beyond scope, but it has to do with efficiency.

 

*Note: Just as 120v sockets/plugs are distinct from 240v sockets/plugs, 1p sockets/plugs are distinct from 3p. So you physically can't cross-plug a tool into the wrong type of power. The risk of cross-wiring is [primarily] limited to bare-wire/hard-wired connections (where the tool just comes with wiring terminals). For liability reasons, fewer and fewer tools are being delivered without an installed 6' cord with plug attached. The exceptions are 3p or those higher-HP tools that fall under the 'hard-wiring' section of the NEC (I believe starts at >=40a). There is another wiring standard that comes into play at 60a, but unless you're installing a wide-belt sander or 30" planer, you'll never come across that need).

[wtnhighlander]

As Eric hinted above, you are going to have a hard time getting the utility to supply you with three phase power in a residential building. You CAN convert 1 phase to 3 phase youself, but it isn't terribly efficient to do so. The fact that you had to ask this question indicates that you should obtain a good deal more education on this matter before you try something like that, anyway. Unless you are going commercial, I suggest that you forget / ignore 3 phase...

He who dies with the most tools ... leaves a great estate sale.

[mds2]

My advice, Hire a professional. I need to upgrade my electrical in my shop and beyond knowing how to change an outlet or ceiling fan I don't know squat about electrical.

I consider myself very handy around the house, but I'm not going to screw up with something high voltage and kill myself.

[sjeff70]

Thanks gents, 3 hot legs...okay.

I appreciate the extra input.   

 

 

[Pbmaster11]

The fact that you had to ask this question indicates that you should obtain a good deal more education on this matter before you try something like that, anyway.

He who dies with the most tools ... leaves a great estate sale.

Why do people use this comment? This person is curious about the situation. Questions are meant to be asked. Just because one asks a question doesn't mean they should disregard the task and move on... Advise caution or direct them to a pro but don't pity them with the lack of knowledge. Everyone is head to learn.

Highlander I am not picking on you. Just making a point.

Typing on cell phone. I apologize for any typing errors.

[wtnhighlander]

Why do people use this comment? This person is curious about the situation. Questions are meant to be asked. Just because one asks a question doesn't mean they should disregard the task and move on... Advise caution or direct them to a pro but don't pity them with the lack of knowledge. Everyone is head to learn.

Highlander I am not picking on you. Just making a point.

Typing on cell phone. I apologize for any typing errors.

I certainly take no offense, and intended none to the OP. I work in a heavy industry, dealing with electrical equipment. I have seen exactly what can happen when an electrical job is attempted without the proper knowledge of the risks, and I only wanted to encourage the OP to become fully informed before attempting the task himself.

[Pbmaster11]

I agree!

Typing on cell phone. I apologize for any typing errors.

[Pwalter5110]

I have wrote a response a couple of times now. Every time I feel like I come off argumentative which IS NOT how I want this to be taken. 

 

See, I work on Toyota Hybrid systems every now and again. (They don't break often) but the transmissions are essentially 2 separate 3 phase motors. I know my fair share about 3 phase electricity. At least in relation to the automotive field. Which isn't very much different than industrial/commercial usage. 

 

I agree with PB that most of the time, you should try and "figure it out". But at some point, there has to be a line drawn where it becomes unsafe.

 

It's easy to say that you should be "fully informed" but how does someone know when they actually are "fully informed". I got shipped to Toyota training centers to learn all about keeping myself safe, and how it worked. Without those classes, there is no way that I could work on those cars safely.

 

I can look for information online. But not all of it is factual. Sometimes safety gets left out of the articles. Knowing how a system works, doesn't make it safe to work on. Professionals die working on electricity. They are "fully informed"

 

Just my .02

[wtnhighlander]

See, I work on Toyota Hybrid systems every now and again. (They don't break often) but the transmissions are essentially 2 separate 3 phase motors. I know my fair share about 3 phase electricity. At least in relation to the automotive field. Which isn't very much different than industrial/commercial usage.

This is hijacking the thread somewhat, but I'm curious about these hybrid gas/electric drives. What is the bus voltage between the alternator and traction motor? I'm intimately familiar with industrial 3 phase VFDs, and for a 480 volt AC motor, the DC bus voltage from the rectifier section of the VFD is about 700 volts. Automotive drives aren't that high, are they?

[Pwalter5110]

This is hijacking the thread somewhat, but I'm curious about these hybrid gas/electric drives. What is the bus voltage between the alternator and traction motor? I'm intimately familiar with industrial 3 phase VFDs, and for a 480 volt AC motor, the DC bus voltage from the rectifier section of the VFD is about 700 volts. Automotive drives aren't that high, are they?

What you are referring to, and what I am thinking your referring to may be a little difference. In a hybrid transmission there is a motor generator 1, and motor generator 2 (MG1&MG2)

 

MG1 recharges the hybrid battery and provides power to MG2 (I am assuming this is what you are referring to as your alternator. 

 

MG2 is mostly used to spin the tires. (your equivalent to a traction motor.

 

If we are on the same page, the 2nd generation Prius (2004-2009) maximum output is about 500v and something like the highlander hybrid is about 650v

The 3rd generation prius is about the same as the highlander.

 

The hybrid battery has right around 200-280v depending on the yr and vehicle.

[wtnhighlander]

What you are referring to, and what I am thinking your referring to may be a little difference. In a hybrid transmission there is a motor generator 1, and motor generator 2 (MG1&MG2)

Sorry for the different terms. The only ICE / Electric drives I know anything about are diesel-electric locomotives, which call them alternators and traction motors. On the locomotives I know, the traction motor is DC.

Thanks for the info, it is fascinating stuff.

[Brian Jenkins]

Typical Small Business 3 Phase:

120v

120v

208v high leg

If you only have one high voltage wire behind your home/shop you can only be fed single phase. If you have two or three you may be able to request 3phase service.

Here, 3 phase customers also have demand usage and they're kW/h is higher than residential.

Phase converters may be used to generate the 3rd leg but its not as efficient and the converters can be expensive.

Unless you are in a commercial zone with available 3 phase power I wouldn't bother.

Sent from my XT1049 using Tapatalk

[calblacksmith]

Well, a voice from the other side here.

As others mentioned, 3 phase is easy to make from 220 2phase (home power) for around a hundred dollars or so, you can make a converter to power up to 5 hp and more if you wish motors.

 

I made my first 3 phase converter over 29 years ago and have refined it a couple of times since then.

 

As someone else said, it depends on where you buy your gear. Home Depot, no you will not need it. I tend to shop Craigs list and auctions. More than half of my equipment is 3 phase. Used commercial 3 phase equipment goes CHEEP because everyone adds in the cost of a new single phase motor to run it in their home. If you can make the 3 phase, that works to your favor. My latest tool is a PM66. It has a 3 hp motor 3 phase on it. Not a thing wrong with the saw that a coat of paint would not fix, I paid $200 for it, with the full size extension to the right and a Besermyer (sp) fence.

 

When looked at that way, the slight cost of making a converter (you can buy one pre made but they tend to get expensive quick for the better rotary ones) is much more than paid for with the purchase of one machine alone then it is gravy after that!

[Spencer_J]

I am constantly looking for woodworking machinery of any phase if its a good fit. I'm fortunate to have a power pole about 20 ft from my shop and can get a three phase service. If i couldn't, i would make a converter.

Doing DIY electrical is all about education.

Pardon my Rant:

My heart breaks when woodworkers make large ( or small) machinery purchases based on what is existing electrically in their shop or workspace. "220 is not an option" or "i only have a 15 amp circuit"

Wether the person pays an electrician or wires themselves, it is so simple to add 220 plugs and move wiring to maximize the locations of their machines. The beauty of electricity is that it can go anywhere!

If someone doesn't want to wire themselves, find a reputable, referred, affordable electrician and become friends with them. They can make your wildest dreams come true.

When i worked as an electrical apprentice, my boss always enjoyed collaborating with his clients and improving their quality of life. I've found that to be true with all residential electricians i have dealt with. Just make sure you clear all of your crap out of the way so they can get to work!

Whichever motors you work with, don't let your existing electrical set up hold you back!

Sent from my thumbs

[mikem]

Spencer_J, let me see your thoughts on this as I believe my situation is a little more complex than just running another line to the shop.  My shop is in the garage, the house is a tri-level with the electrical panel in the basement, which is on the complete opposite end of the house.  I have estimated about 100'-150' of power cable would need to be ran to get through what looks like a potentially complex run.

 

The next challenge is that the main box is a completely full 60 amp (yes 60amp) service.  (Box is Square-D circuit breakers)  What I would love to have is to upgrade the main service to 200amps, move the existing 60amp box to the shop as a sub-panel.  Because of the length of the cable and the complexity of the run, I am thinking that this could be a very expensive solution.

 

The only other thought I have, is that the dryer is right next to the shop.  However with our active family it is almost always running when I am out in the shop, so I don't believe that is an option to tap into.  It is on a 30 amp 220 circuit, and I am pretty certain the wiring wouldn't be a high enough gauge for a 60amp subpanel.

[Tpt life]

So much of this depends on your house style but let me add two cents. You'll never regret moving to 200 amp service in our modern world. While you may never draw 100 amps, you will have tremendous isolation flexibility. Freezers and refrigerators can exist on dedicated slow burn breakers that can extend the life of the compressors. Many utilities will not charge for the service update and many inspectors will allow back feeding your old work from a new panel. I would find someone who won't charge you to at least estimate some options for you.

[Trip]

==>The next challenge is that the main box is a completely full 60 amp (yes 60amp) service.  (Box is Square-D circuit breakers)  What I would love to have is to upgrade the main service to 200amps, move the existing 60amp box to the shop as a sub-panel.  Because of the length of the cable and the complexity of the run, I am thinking that this could be a very expensive solution.

 

The move to 200a would not be wasted -- I believe 60a is about the absolute minimum allowed by code... Reusing a Square-D panel for your shop may also save you $$. The run may or may not be as bad as you fear -- experienced electricians are pretty clever about pulling cable - won't cost you much to bring-in a pro for a look/estimate. The length of the sub-panel run will cost you -- I don't have my NEC handy, but I suspect you'd have to pull 6g to about 100' and 4g to about 200'... I've got a couple of 4g pulls and you really want a pro for those...

 

One thing the electrician may suggest -- moving your service disconnect and feeding your existing panel as a sub and run a new panel for the shop -- I had that done in a previous home and the total cost was quite reasonable. Point is, pros are a good investment...

 

Good luck.

[Spencer_J]

Spencer_J, let me see your thoughts on this as I believe my situation is a little more complex than just running another line to the shop.  My shop is in the garage, the house is a tri-level with the electrical panel in the basement, which is on the complete opposite end of the house.  I have estimated about 100'-150' of power cable would need to be ran to get through what looks like a potentially complex run.

 

The next challenge is that the main box is a completely full 60 amp (yes 60amp) service.  (Box is Square-D circuit breakers)  What I would love to have is to upgrade the main service to 200amps, move the existing 60amp box to the shop as a sub-panel.  Because of the length of the cable and the complexity of the run, I am thinking that this could be a very expensive solution.

 

The only other thought I have, is that the dryer is right next to the shop.  However with our active family it is almost always running when I am out in the shop, so I don't believe that is an option to tap into.  It is on a 30 amp 220 circuit, and I am pretty certain the wiring wouldn't be a high enough gauge for a 60amp subpanel.

mike, sounds like a great challenge! 

 

i think that a service panel upgrade is due. your panel may be overloaded.

 

get a survey from the power company, see which size wire comes into your home.

once you determine that, you can either upgrade your panel right away to match the appropriate size or request an upgrade in the line from your provider. 

by upgrading your panel, you get more physical space to add new circuits. side note, the power company will pull your meter for free to allow you to work on the panel without risk of shock, they will then return with a new meter when you're ready. if you tamper with the meter without their approval, you could get into trouble!

 

just because you upgrade a new panel, doesn't mean you have to re-wire the whole house, you essentially just re-connect the old wires to the new box. you can always use the panel to splice old wires to new wires to reach the new breakers. 

 

some simple options that come to mind,

i'll PM you to get some more details which could really effect how to solve your problem. don't want to take over this thread but want to help others.

 

keep the dryer line, branch off from there to your shop. install a switch at the dryer. 

 

move the laundry closer to the panel and use that existing 30A line to feed your shop. 

 

-it's not legal to put two 30A wires onto one leg of your new 60A and then one 60A wire for your second leg to try and reduce the cost of wire-

 

move your shop closer to the panel and reduce the length of your run. 

 

definitely get a free rough quote or estimate from a few electricians if you're not comfortable tackling it. try looking for any old wire specialists or panel upgrade specialists, if they've been in business for a while, sometimes the local inspectors will be much more comfortable approving their work as opposed to a young small company or a mr. electric type of service electrician. 

[sjeff70]

3ph machines are a little lower in price, but generally those machines were heavily used in a school or shop.  

But if you're looking for larger vintage jointers and planers there's no option but the 3ph.

 

I've been researching the 'new' Oliver machines and they appear to be in league with the PM and SS.  

Oliver, PM, and SS are high-end Taiwan made machines (at similar price points) and Oliver seems to be in a league of their own with their (large) jointers.  

[mikem]

I have had the power company out, the line from the pole will support up to 400 amps.

[Tpt life]

Dude, 100 amp panel in the spot of your 60 and another at your garage end. Both panels will require grounding but you'll be able to sell the house to anybody, even a hobby welder. That would be my long term goal with 200 amp panels instead if an outbuilding is feasible on your property. A pro estimate will flag any hidden costs.