I am buying a Powermatic 66 Table saw. 3 hp 220v single phase.
I’m actually planning on making a 12ga extention cord about 25′ long and plugging it in as needed to the dryer outlet.
I’ll preface the next part with saying I’m a finish carpenter who has done many remodels and wiring along the way. I’ve added many extra breakers and circuits over the years and know how to figure out if the panel can handle another draw. I’m overly cautious. I know the mechanics of electrical but am not familiar with 4 wire 220 and how it should be run.
Now…Guy says it’s 3 wire 220v (2 hot 1 ground) and I have that type of dryer outlet. I need to spend today preparing the circuit. With my luck it’ll be 4 wire for which my home is not wired. I’ll need to make my 3 wire 220v outlet – 4 wire.
Is this an easy task for someone of my abilty to figure out? The existing 3 wire 220 circuit is in conduit about 15 feet from the panel. It would be very easy to add another wire in there ( I don’t think it would over load the space-what can I fill 65% of the conduit with wire correct?)
Owner says he’s used a plug in the past but others say I should hard wire it. I’d turn the dryer outlet into a j-box if this is a 100% must do. This is not as convenient as now I’ll have a 12ga wire going across my rather small shop. I prefer to be able to plug in as needed.
Anything else I should know?
Thanks,
Notrix
Edited 1/15/2005 11:42 am ET by Notrix
Replies
ive done almost the same thing with my unisaw and im happy with it but with mine its just an extention cord and i unplug the drier and plug in the saw. I dont know alot about electricity (i too am a finish carpenter, however ive had less electrical expirience) but i did some reserch at the time and it seemed that 12ga was too small of wire.
I wish i could remember the spacifics, but i used 10ga
I dont think that my lack of electrical knowlege will be helpfull but feel free to ask and since i have a similar set up i might be able to help.
Congratz on that PM66!
EDIT: i reread and realized i forgot this: where does 4wire enter the picture? the 4th wire is simply a 115v circit to run clocks and stuff like that that might be on the drier.. So let me get this straight..
The saw is 3wire
your drier is 3wire
...i apologyse, maybe just my ignorance but i dont understand where the 4th wire enters the picture.
______________________________________________
--> measure once / scribble several lines / spend some time figuring out wich scribble / cut the wrong line / get mad
Edited 1/15/2005 11:55 am ET by skyecore
Thanks everyone,looks like a go.My confusion can from that the way I understand it the 4 wire is now code in CA, meaning you can't even install a new 3 wire 220v outlet "legally".Once again I'm pretty good at being directed on electrical but am ignorant of code. I know my limitations and shut off the whole house if even slightly confused.My first job as an apprentice carpenter I had to stand on a rickety box and plug in a pigtail with alligator clips to the panel for 220v. The boss would stand below be primed with a 4x4 to knock me off if I got "plugged in". I never figured out if he was messing with me but I've always been safe when it comes to electrical.Thanks again,Notrix
He wasn't messing with you. He was just very stupid to expose you to such a risk
Funny guy huh?Anyway I posted the same subject at Breaktime and got more technical answers that the more curious of you may find interesting.Here's the thread: http://forums.taunton.com/tp-breaktime/messages?msg=52671.1
If the link fails you can do a hard search for this title:
"Wiring 220v Machine on Household Current"Thanks once againN
Notrix: If you ever saw the safety film where the worker dropped a wrench (or screwdriver or big 'gator clip) across a 220v household size service you would s**t. Burnt the skin off his face and set all his clothes on fire. This was just a regular old 3 wire 100 amp 220 service. The wrench was just about burnt in half. It doesn't need to be a three phase 480v 600amp service to hurt or kill. Any extension cord for a tool should be rated for the breaker feeding the curcuit. Manufactures can get away with smaller cords because their equipment is UL tested and approved. A #12 cord is not going to burn up or even overheat under normal duty factors (time on and off of utilization equipment, the saw) but don't mess around. #10/3 SO cord is available and not that hard to work. It is what I used on my 3hp Laguna bandsaw.
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Edited 1/15/2005 6:16 pm ET by duke-one
You have a little bit of work to do.
3-wire dryer outlets are 240/120V, non-grounding receptacles (2 hots plus a neutral). These are not permitted to be installed per current code (this was changed in 1996). Dryers and/or ranges are permitted to use these if they already exist, and the frame of the appliance is attached to the neutral wire: a crazy idea, especially for appliances often located in the vicinity of grounding plumbing pipes.
Your saw needs a 240V, grounding receptacle (2 hots plus a ground). So what you need to do:
--the best thing for a 3 HP induction motor is to hard-wire it on a dedicated branch circuit;
-- if you insist on sharing it with the existing dryer branch circuit, you need to replace the 3-wire receptacle with a 4-wire receptacle (2 hots, a neutral, and a ground). Since there already is metallic conduit, you can just run a bare wire from the ground connection on the receptacle to the junction box (I assume the box is metal), using one of thse green grounding screws or clips made for this purpose;
--Replace the dryer pigtail with a 4-wire one, where the frame will now be grounding by the ground wire, not the neutral. There will be a neutral-to-frame bonding screw or strap in the dryer you will have to remove.
--On your extension cord, you use a 4-wire plug, but leave the neutral unconnected. If the breaker is a 30A breaker, the extension needs to be 10 gauge.
Barry,
I ran my saw from a 220V dryer outlet for a long time, before I rewired, simply by using a 3 wire extension with a dryer plug. Plug out the dyer, in the saw and in business.
The dryer outlet is supplied from the main board, where neutral is connected to ground anyway, or am I missing something?
Jellyrug,
This is not according to code, and in the general case is not a good idea.
If the dryer outlet runs directly back to the main main panel (no subpanel) and the main panel really is wired as a main with the neutral and ground bars bonded together, then yea, the circuit is functionally the same. The wire is the wrong color (white instead of green), and the wrong type of plug is used.
However, there are many cases where this is not the case. In some parts of the country, California for one, it is very common to mount a meter base with a disconnect outside, and the "main" panel is inside, where it is in fact wired as a subpanel (with separate neutrals and grounds). Also, alot of shops are fed by subpanels. In this instance, tying the saw's frame to a neutral connected to a subpanel means you're tying it to a neutral that downstream may be carrying a very high current. In other words, the neutral bar in the subpanel will not be a at ground potential, and neither will the saw. If the saw touches a grounded object, it may end up carrying some of that neutral return current. The operator could feel a "tingle" if they touch the saw and a ground (such as a concrete floor) at the same time. This is not a good thing with sometime as dangerous as a table saw.
So no, I don't think it's a good idea to put a 240/120V non-grounding plug on a table saw cord, instead of the correct 240V grounding plug. There are circumstances where it would be unsafe.
Barry,
Everything you said is correct, I had think about this.
A dryer, runs the motor in 120V and the heater in 240V, from two hot wires and a neutral. Amazing that they actually allow this. On a rare occasion, with a certain short circuit condition, you can actually get a nice jolt from this installation.
IEC (Europe) code 220V is supplied from the supplier, with one live (hot) one neutral which is not hot and a ground (earth) for residential. The main breaker in the panel has to have ground protection, and if you touch neutral to ground at any point, the main breaker will trip on a ground fault.
Edited 1/17/2005 8:04 am ET by Jellyrug
Notrix
I have the PM 66, and have been using it for 2 years, almost every day. Mine is 220V, 3 wire circuit (2hot, 1 G). I have wired it with a 10 guage 20 ft. lead, with a plug on the end that fits into a 20 amp 220V outlet in shop wall. Purchased it new. I don't know how old your saw is, but it should be the same. The only tool in my shop which is hard wired is my very large compressor. Even my jointer, which is 12 inch Northfield HD 3 phase, is on a plug. It's more difficult to move em around if they are hard wired.
Jeff
Jeff What type of plug and receptacle did you use for the 3 phase and where did you get them. I have that situation right now with a saw and DC. Thanks in advance
Brian
All: I've seen some terrible advice and some decent advice in this thread. This electrical safety stuff is too important for half measures. How about some way of limiting answers to those who really know? Not easy to do but someone is going to fry them self or their shop.
KDM, Amateur WoodWorker, Professional Electrician, retired<!----><!----> <!---->
Kenneth Duke Masters<!---->
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Hi KDM,I agree, but forums like this are not always blessed with the participation of professional electricians such as yourself, and so the call goes out for people to relate their personal experiences in hopes that we all can learn from them.As with all free advice, you get what you pay for. While no should pass themselves off as an expert when they're not, likewise no one should base critical safety decisions solely on anonymous advice given in an online forum.What might be a good idea, is to adopt the ethic used in other woodworking forums, in that, if you're giving electrical advice, you should clearly state your qualifications, or lack of them, in your post.Tom
Tom: Sounds good to me. Anything to keep people from hurting themselves in the ways I have seen on training videos. One of the common misunderstandings is that 120/208 voltage you find in your home or home shop won't do much damage. More homeowners get hurt or killed messing around with household wiring or appliances then electricians working with kilovoltage equipment. How about a separate place for electrical discussions? That might keep it on subject (wishful thinking?) and allow important details to be presented clearly.
KDM<!----><!----> <!---->
Kenneth Duke Masters<!---->
The Bill of Rights December 15 1791<!---->
NRA Endowment Member<!---->
LEAA Life Member<!---->
CRPA Member<!---->
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Or maybe it would be easier to keep doing it the same way we have for years and let the authenitic experts mercilessly taunt the bad advice and those who offer it. After all, this is a Tauntin' forum, isn't it?
Duke,
How do you qualify someone as a Professional Electrician?
We have a licensed contractor, who passes a code exam and has to work for a contractor to qualify before he can get his own licence, no other requirements. One can do this with limited experience.
Manufacturing has exemption, so when it comes to all the nice Industrial stuff, such as transformers, power factor correction, electrical distribution, PLC's, grounding, cleaning your supply up to the third harmonic, knowing what lighting to use in which locations, cable sizing, when running multiples in a pipe as compared to air, there are no formal requirements here in the US.
Other than a Licensed Contractor, how do you decide if a person is an Electrician?
Personally, I have not done electrical work for the last 15 years, prior to deciding to rewire my whole shop to 240 (this is what it actually measures where I live in California). I got a permit, did the job myself and had it passed by an inspector. No qualifications were requested.
So, to get back to your original post, how do we decide who is qualified to answer these electrical questions?
Uncle Dunc: I don't have the energy or the bent for "Tauntin". What I have is a head full of knowledge that, in retirement, isn't very useful around the house or even in the shop. Change the voltage on a motor run a small circuit put up some lighting, all little stuff. That is also the nature of the electrical questions here but it is a good feeling to help others avoid dangerous or costly mistakes. JellyRug: That is a good question but not that hard to answer. Since were not talking 4160 or 2400 volt motors or PFCC or PLC or 500mcm wire and 4" rigid steel conduit we don't need a full fledged industrial electrician. Even "ropers" (residential electricians) could fill the bill. What I worry about is some of the advice I have seen here even where most of the post made sense. Someone said recently " an extension cord for a 3hp saw, come on" like it couldn't be done, just some #10 or #12 SO cord and proper connectors. How about an extension cord for a 500hp motor, not common but far from impossible. It shows that a lot of unqualified people here are dispensing advice. It is true on a web forum like this or anywhere on the web anyone can say anything and who knows who is at the keyboard. I retired before we were supposed to get licensed due to a new state law (about five years ago) so I am not licensed but I do know what I am talking about. I've been there and done it. Short of submitting my qualifications to testing or sending a letter from my previous supervisor or employer how could I prove it? That would not be practical here.
>So, to get back to your original post, how do we decide who <
>is qualified to answer these electrical questions?<
If you were qualified to decide who was qualified you wouldn't need electrical advice. That sounds harsh but how else to say it? I can't prove what I know other then to have another (known) electrician evaluate what I say.
KDM<!----><!----> <!---->
Kenneth Duke Masters<!---->
The Bill of Rights December 15 1791<!---->
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I agree fully with you - "If you were qualified to decide who was qualified you wouldn't need electrical advice."
I was the one who said "an extension cord for a 3HP saw, c'mon"...
I didn't say it couldn't be done... what I said was "do it right". Meaning it shouldn't be done.I also said: use appropriate connectors and that the goal was to make the safest, highest quality installation possible. I'll stick by that.Now, you could use an extension cord, but most larger saws are not mobile and should be wired without an extension cord. Not that it can't be done, but if it doesn't need to be, it shouldn't be.Extension cords, as you well know, can get cut, smashed, or pulled out; and can be dangerous. My comment was if you can, do it right. I'm shocked that you would use me as your example of the "bad advice" that was given, because much of it was truly bad advice.My comment about the good advice in this thread was mostly about your advice. We may not agree on the cord, but my thinking is always if you can, do it right. Just because you don't agree, doesn't make it bad advice and you were offbase.As for qualifications, I am licensed. Have been for years. And am a Journeyman Wireman with the IBEW, and a Journeymen Industrial Electrician with the URW. I've only worked in industry for 22 years, from construction to industrial electrical. I also founded an industrial controls manufacturing company to design and build industrial electrical control systems. It's quite successful. I'm quite familiar with NEC codes, and industrial electrical design codes as well. I could go on, but this is a woodworking forum. Just because my signature doesn't say "electrician", don't jump to conclusions.So when you use exmples of bad advice, make sure it's bad advice, not just a difference of opinion in what may be "best".Respecfully between tradesman I remain your friend,scottd.
No offence meant, Scott. I just don't see anything wrong with a proper extension cord. Yes it can get in the way and get cut or squashed but so can the original factory cord. One downside would be the expense of quality cord caps and connector bodies. One upside would be a ext cord could be used for multiple machines that weren't being used at the same time resulting in fewer hardwired circuits, if electrical parameters were similar.
I reread the post in question and the only part I took minor exception to was where it seemed you were saying an extension cord was not acceptable. If that's not what you meant, my apologies. A difference of opinion or my misunderstanding, yes. Now that I know you are very qualified what do you think of my original point that some electrical advice in these forums is very unsafe or at least not complete? Lets work together to help everyone be safe out there.
Sincerely, KDM
PS: Do you think there is some way of getting the electrical safety films we have seen to the woodworking public? Would it be worth it? There is so much electric equipment in wood shops and so many working on it themselves it would almost make sense.<!----><!----> <!---->
Kenneth Duke Masters<!---->
The Bill of Rights December 15 1791<!---->
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Thanks everyone!! I really appreciate the advice from those who have done similar set-ups and those trained to do it by the book.It's difficult to explain and interpret exact situations. if I was expert at electrical I'd be hard pressed to give any advice under these circumstances. Being a renter in limited space makes it tough to figure out on line.I have a much better understanding and appreciation of this type of set up now and feel confiedent I have a safe saw.I have a friend who's a 25 year journeyman electrician and I see him once a month or so and he'll be glad to give it the once over. I couldn't get in touch with him so I relied on you guys.Hopefully this thread will make it clear for the next guy doing the same.Regards,N
You are absolutely correct, and many people had backed that up so I didn't add additional comment.The challenge when dealing with a forum like this is to understand the limitation of censoring advice. Anyone can post, and many who believe they are helping are actually giving poor advice.They are not doing it intentionally, it's just "the way they've always done it". As I had said, that doesn't make it good, or correct, or safe.It would be hard to try and verify the credentials of the advice givers, given the context of this forum, it would be wiser for users to ask "I have an electrical question, are there any professional electricians out there", and then proceed to get professional advice. Many won't, some will. You did it right. You gave your qualifications and gave sound advice. As for my original post, my point was that we strive to set our goals in our work high, don't shortcut your shop, and certainly not your safety.My second factor is that most non-electricians who are doing work themselves never pick up all the advice, so when you advise "extension cord", it's usually less than what you were really saying. You said "heavy SO cable with 10/3, cinch wire mesh strain reliefs for pull-out protection, and 30A plugs"... all they hear is extension cord.Good work on your advice. My heart's in furniture and my days are busy, so I'll let you handle the electrical installation column.
thnxscottd.
Scott
This is a very basic question.
Can you explain in layman terms the difference between 240 vs 208. I have run a (what I call 220) for my cabinet saw. It was two hot wires each from a 110V breaker (one from each leg of my service plus a bare ground wire).
Now I am finishing off the room over my garage and am planning to install baseboard heaters. I'm looking at heater models either 208 or 240.
Is the 240 the same as what was needed for my saw?
Thanks for any help
Bill D
Home electrical services are almost always 120v/240v single phase (it's sometimes called 115/230 or 110/220, depending on where you live, but they're all the same.) On the other hand, you get 208v from a three phase service, as in 120/208v, which is pretty common for commercial electrical services but hardly ever available for residential use.Some heaters may be labeled as only for 208 or only for 240, but they could be labeled 208/240 which would mean they'd work on either voltage (they'll put out a few more watts of heat at the higher voltage.) So, for your purposes just make sure whatever heater you buy says it can be used on 240v single phase - it may or may not be usable at 208v as well, but that won't matter for your purposes.And to stay in line with the recent posts in this discussion, I'm a professional electrical engineer (so hopefully I know what I'm talking about... ;-) )
Yes, the 240 volts that you find on your system (across the two legs, or 110V from one leg to neutral) is the correct voltage rating you want for your heaters. As well, your saw was most likely rated for 240V, or it may say 208/240 under the voltge rating.The difference in the two is that a true 208 volt system is typically a "wyw" system, which refers to the way the transformers are connected to distribute the power at a given voltage level, like 208 volts, or 240 volts. Most common is a delta system that produces 240 volts of power across the two legs of your service panel.There aren't many of the wyw systems used, except in industry. I haven't seen a 208V system in a home for years.Another note is that a motor, for instance, that is rated 208/240 is capable of running on either voltage. At 208 volts the motor will draw slightly higher amperage than it will at 240V. On the nameplate where your data is you will also see an amp rating, which will tell you the full load amp draw of the piece of equipment. If the voltage rating reads "208/240", then you amp rating will read "xx.x/xx.x", showing you the amp draw at 208V, and the amp draw at 240V.So the simple answer is: 240V for your home and shop are correct. The ratings 110/120, and 115/130 are all talking about the same 110V that is supplied to your service panel from one leg to the neutral.
I hope that helps.
thnxscottd.
scottdDamschroder Scott Furniture[email protected]A craftsman needs three things: Accuracy, Technique, and Quality. Accuracy can be set; technique can be learned; but quality must be bought and built.
>> ... it is a good feeling to help others avoid dangerous or costly mistakes. Yes it is, and I suggest the best way for you to help is to continue to monitor the electrical discussions and raise an objection when you see bad advice being offered.Electricity is not uniquely dangerous. I see far more reports of amputation injuries here than electrical mishaps. I've heard more stories of woodworkers being killed by table saw kickbacks than I have of woodshop electrocutions.Nor are electrical mishaps uniquely expensive. We hear many more stories of expensive to repair finishing disasters than we do of miswired motors losing all their smoke.Anointing experts is not the way we do things here. For one thing, I don't think Taunton would be eager to accept the liability that would attach to selecting and empowering an electronic guru. The advice situation at Fine Woodworking is much the same as it is here. If the readers question the safety of any technique or material they see in the magazine, the write in and complain about it. Then other readers complain about the complaints. The editors very rarely take an official FWW position on these questions.FWW publishes a safety warning in every issue of the magazine that starts out, "Working wood is inherently dangerous. Using hand or power tools improperly or ignoring standard safety practices can lead to permanent injury or even death."Knots has scraped along for some years now working in that framework. I'm not persuaded that there's anything wrong with our electrical advice process. And I'm certainly not persuaded that it's so badly broken that we need to make a radical departure from our existing practice.
Edited 1/17/2005 11:45 pm ET by Uncle Dunc
Fourth wire is only for applications where the neutral and ground have to be kept separate. Mostly mobile homes and some localities ( the local inspector and local rules rule). All you need is two hots and a ground (not the neutral!). The 30 amp circuit might be a bit high for the saw and to be exact any cord on a 30 amp circuit shoud be #10. If the outlet is 4 wire figure out which is the ground (probably the one with the 90 degree L shape) and use it and the two hots. There is an execption in the code for driers and stoves where the neutral side of a clock or timer or oven light can use the ground as a neutral, this is a no-no everywhere else.
KDM (Electrician for thiry years)-->--> -->
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Edited 1/15/2005 12:44 pm ET by duke-one
Edited 1/15/2005 12:53 pm ET by duke-one
The fourth wire (really it is described as 3 wire with ground) is only needed when the appliance needs both 240 volts and 120 volts. The white wire is a neutral. An electric drier uses 240 volts for the heating coils and 120 volts for the motor and controls. With 4 wires, the red and black make up the 240 volts and the red OR black paired with the white make up the 120 volts. When you open up the drier receptacle, you should find 4 wires.
Your saw is 240 volts so it only needs a two wire with ground circuit.
For your 240 volt extension cord, you only need a two wire with ground of sufficient size for the amperage of the saw. You can put a drier plug on one end that mates with the drier. Wire the red and white(be sure to use a magic marker and color the white wire black so someone later knows it is a "hot" wire) to the outside hot terminals on the plug and the green ground to the ground lug on the plug. Nothing gets wired to the neutral lug. Put a receptacle on the other end of your extension that mates with the plug on your saw.
How many Amps does your saw draw? If it draws significantly lower that 30 I would not plug it into my drier plug. Your drier is wired to a 30amp 220volt breaker. You need to run a new line to your shop and install an plug that is rated for the proper voltage and amperage. Otherwise you are looking for trouble.
Derek
Hey,
So you're a finish carpenter. Every one of you guys I've met are somewhat perfectionists, that's what makes you good. Also, most of you don't take short cuts and are particular about quality. I'm guessing you're the same.
Well, by trade I'm an industrial electrician, and certified as a journeyman for too many years. My heart builds furniture, but my hands wired the tools for years.
My question is why would you shortcut on wiring your saw? An extension cord for a 220V 3hp saw? Com'on.
You wouldn't do that on your work, don't take those chances with your saw, your safety, or the safety of your family.
You have some excellent advice here. Hard wire it into a box correctly. Use approved electrical fittings, don't just "stick it through the hole". And make sure your connections are tight and taped.
Use 10ga, no question, if you're connected to a 30A breaker. The breaker will trip before your cable will fail.
Now... don't listen to these "I did it like this for 500 years and it was fine", or "I wired my saw with bare wire and it ran forever and never burned down my trailer shop". These are the things we have done, that doesn't make them smart.
Do it right, just like you do every day. You never be dissatisfied with quality work.
thnx
scottd.
Thanks again,Here's what I've done:20 foot 10/2. It couples with twistlock 240v 30amp sockets 5 feet from the saw which is how the previous owner did so in a commercial shop.Unfortunatly I rent and can't rearrange the wiring . I need to do it this way to keep cord tripping down.My breakers are 30 amp but the saw specs a 20a so I'll switch that out asap.I've run it as is today to see if it all works. I have all the wires correct and while running I get not charge to the saw frame or cabinet. I know this is good but doesn't tell the entire story. I'll definatly install a 20a breaker. Any other saftey issues I can implement? Does a GFCI or similar type breaker make sense for this type of use?Thanks again,N
Edited 1/16/2005 6:21 pm ET by Notrix
You say 10/2, I assume 10/2 w/ground? Other than that, it sounds OK. The goal is to make the highest quality, safe installation that will provide correct electrical service.As for GFI, the answer is no. A GFI protects from instant ground applications, like water, or a direct short. In motor applications the GFI will give you erroneous trips and is not the correct application of the GFI circuitry.It sounds like you have it wrapped up. Keep on with your carpentry, I have so much respect for a good trim carpenter. You are worth your weight in gold.
thnxscottd.
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