I need to run a 220 V cord from my dryer outlet for my 8″ jointer.
Do they make 220 V extension cords?
I have an electronics background so putting on together shouldn’t be an issue.
Whether it’s the best and safest way is my concern.
Yeah, there’s always hard wire with conduit, more work of course.
Any thoughts? Anyone else run across this predicament?
Gary
Replies
I do not know of a ready made extension cord for what you want to do. You will have to make your own. However, there are a couple of things to consider.
First, what is the amperage of the tool and what is the amperage of the dryer outlet? Most dryers run on both 120 volts and 240 volts. The heating coils are 240 and the controls and motor are 120. Therefore, the outlets are of a special type that has both 120 and 240 volts.
To make an extension, you will need enough wire of the correct size for the amperage of the tool. This will be something like 12/2 plus ground which is the wire size and the number of conductors. On one end you will have to install a plug like the one on your dryer however you only wire to the 240 volt terminals ignoring the 120 volt terminals. On the other end, you need a receptacle that matches the plug that's on your tooling.
If you are not familier with wiring, you are best to get an electrician in to wire up the extension cord.
You can get heavy extension cord at Home Depot. I'd use #8 wire (2 wire plus common). Get a plug that matches the dryer outlet. The voltage as measured across the two spade lugs will be 220V and between any one of the two spade lugs and the common lug will be 110V. If you're making a run of over 30', you might consider using #6 wire.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)
PlaneWood
The wire size is determined by the amperage of the tool, not the voltage. Unless his jointer motor is over 3 horsepower, he will not need a wire size more than 12 AWG which is sufficient for up to 20 amps.
That's why the amperage of the tool motor is something we need to know.
Howie.........
Thanks, I'll try to find out the amps, it has a 2HP/1Ph motor.Motor (TEFC):
3 HP, 2 Ph, 230V/460V or
2 HP, 1 Ph, 230V
Does this mean the 3 HP and 2 HP motors are the same???I downloaded the manual from WMH group site, but still couldn't find the amps.Gary
Edited 8/17/2005 5:09 pm ET by webdesigner
>> 3 HP, 2 Ph, 230V/460V or 2 HP, 1 Ph, 230V Does this mean the 3 HP and 2 HP motors are the same???
No, there are two different motors. To determine the amperage of the motor on your tool, look at the motor label. The amperage will be clearly stated. If it's a 2HP motor the amperage will probably be about 10 amps @240 volts.Howie.........
OK here's the latest (for those interested), according to the expert at WMH tools, it needs at least 25 amps.
Due to startup surge. Actually runs at about 12 to 15 amps.
He believes a 12 gauge extension cord on a dedicated circuit should be fine.Gary
Well, lets see. 2HP = 1498 watts. Divide 1498 by 220 and you get 6.8 amps. Now throw in a little for losses here and there and you will be close to 10 amps after the motor is up to speed but with no load. Start boggin it down and it can easily go up to 15 amps. Amps required to get the motor up to speed could easily be around 20 amps.
#12 wire is rated at 9.33 amps, #10 at 14.8 amps, and #8 at 23.6 amps. So, pick what you think is best. If it's a long run, I'd go one wire size bigger.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
"#12 wire is rated at 9.33 amps"?? If so, how come outlet circuits in today's homes are wired with 12 gauge Romex, and the breaker is 20 amps?
Check out this web page: http://www.interfacebus.com/Reference_Cable_AWG_Sizes.html
When an appliance is turn on, the inrush current can be twice what the nominal load current is. Circuit breakers normally installed in breaker boxes are the instant trip type. If you had a 15 amp breaker and turned on a large appliance (say a heavy duty vaccum cleaner) the breaker could/would trip. While a #12 wire would handle more than 9 amps, the National Electrical Code has it rated at 9 amps for safety factor reasons. More than 9 amps and the resistive heating line losses start going up exponentially (I^2*R). Also, at today's energy costs, the extra cost of the next larger size wire probably could be saved fairly quickly due to the lesser line loss.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
I think you really have something mixed up. Household circuit brakers are hardly ever "instant trip". In fact they are almost always what used to to "slo blow". They will take three to four times their rating for startup surge.
As to your reference, I suggest you read down past the table. You will see that they quote the NEC standards for wire which are as I, and others, have stated. Nor, is there any significant electrical use savings from using a wire larger than required as long as the amperage capacity of the wire is not exceeded.
I suggest you stop posting in this thread. Your info has been incorrect and misleading.Howie.........
Planewood --
While residential circuit breakers may be called "instantanious", they're actually designed to not trip on inrush currents. For instance, I'm looking at a trip-time curve for Square D's QO line of breakers. They'll typically handle their rated current forever, 2 times their rated current for about 15 seconds, and 4 times their rated current for 2 or 3 seconds.
For the breaker that's called inverse time.
My jaw dropped when I read the amperages on the link but reading a little farther down the page: 'Refer to the NEC rules to determine building wiring, as this page relates to electronic equipment wiring'
Bingo! I was going to point out this increadible well of misinformation. But I just hope that newbies can read between the lines.
Mike
From the page that you reference:
The National Electrical Code [NEC] requires their own cable sizing for premises wiring. Refer to the NEC rules to determine building wiring, as this page relates to electronic equipment wiring. For reference, the ampacity of copper wire at 300C for common wire sizes14 AWG may carry a maximum of 20 Amps in free air, or 15 Amps as part of a 3 conductor cable.12 AWG may carry a maximum of 25 Amps in free air, or 20 Amps as part of a 3 conductor cable.10 AWG may carry a maximum of 40 Amps in free air, or 30 Amps as part of a 3 conductor cable.8 AWG may carry a maximum of 70 Amps in free air, or 50 Amps as part of a 3 conductor cable.
Can I ask this, then? If a motor is rated at 20A @ 220, is it not true that it is 20 amp combined, or that each 110 leg is providing 10 amps? Each leg is not suppling 20amps of power. I have allways devided the amp rating by 2 to determine the wire. For innstance a 30A 220 rating would call for a minimum of a wire/receptical/breaker that could handle (each conductor) 15A . or in this case a 30A breaker/recepticle and a conductor that at a minimum handle 20A I tend to go one size higher for being able to add a larger machine with out replacing the wire.
Bones,
These electrical discussions always get off the track, by some margin.
Guess it's because we cant see those little electrons moving, with our bare eyes.
Consider your table saw is a water wheel needing 20 gallons per minute, the receptacle is a water pump. The two lines going to your saw, one supplies the water to the wheel and the other returns it to the pump suction. So you have to send 20 gallons per minute through each the supply and the return line. Exactly the same goes for the current (amps) flowing through your wires.
In short, you cannot divide by two.
Amperage is per leg, or wire. With a 220v 20amp line there is not two seperate 110v 10amp lines combined to equal the 220v 20amp total. The amperage it what it says it is on every leg. In fact the "real" voltage coming out of the transformer is 220, that white wire (the common) is conected to a "center tap" which reduces the voltage by half. So a 20 amp 220v (2 pole) breaker is rated for 20 amps on each pole.
There are a lot of good books that explain these theorys well. Check out Home Depot or the Library. I think that any woodworker with machinery needs to learn at least the basics. On this site people often recomend "call an electrician". Well I suspect that these same people have never tried calling an electrician to wire an extra outlet, or make an extension cord or diagnose a tripping breaker. I've been a remodeler for 4 years and in the trades all my life. I can tell you that around here you wont find a decient electrician that really understands what he is doing to come for such a small job. If you need a sub-panel and some branch circuits pulled youll have better luck. But that can easily cost $1,000, and that is when the main panel is close and the wires are easy to pull. The guys that install ceiling fans, replace breakers, and other odd jobs are usually incompetent and take short cuts. It is best to learn your self.
Mike
Very well said. Couldn't agree more.
Cheers. Walker1
It is foolish to use the house wiring tables. You want to use the amperage tables for flexible cords.I expect #16 is suficient. My extension cords are #14.
Good point about using the ampacity tables for flexible cords rather than for building wire, that slipped my mind.Table 400-5(A) in the NEC covers the ampacity ratings for flexible cords. For the types of cords a person will generally find at the store (SJ, SJO, SJTO, etc.) it appears that #12 gauge two conductor with ground flexible cord is good for 25 amps, #14 is good for 18 amps, and #16 is good for 13 amps.
>> It is foolish to use the house wiring tables. You want to use the amperage tables for flexible cords
What are you talking about?
For residential wiring, use the NEC tables.Howie.........
Not to offend you ...The NEC also has a table for the wire size between the recepticle and tools - extension cords if you wish. Those tables are different than for in wall wires.The post above yours summarizes the amperage allowed in the usual cords. (The table restricts the breaker size to 30amps or less.)It is easy for people to overlook this table.
Exactly
Next time yall are freaking out over 6 ga. extension cords for a 10 amp tool look at the wire that the actual machine uses. I think my 3 horse Unisaw has a 16 or 18 ga. cord! Most high current power tools (like a big 15amp router) have 22ga. cords. Obviously those cords are only 4 to 10 feet long, but it sort of puts things in perspective.
Mike
Well, the tables I was looking at seem to say 9.3 amps continuous for #12 wire and 20 amps max current. But, I probably interpreted them wrong.
I have a 100 amp breaker panel here in my shop with about a 40 foot run to a disconnect then to the meter. I used #6 guage for that. My compressor and planer came with #10 wire and I rewired the TS with #10. I used #10 wire in the shop walls for three circuits and #12 in the walls for lights and light duty outlets. my DC, table saw, planer, and compressor are on circuits using #10 wire. The DC and compressor are each on their own circuit. The other high power tools are on the same #10 wire circuit cause I'm never running two of them at once.
Oh yeah, my stick welder is on its own circuit wired with #8 wire.
I do remember that the original #12 cord on my TS would get pretty warm after long periods of use. That's why I changed it to #10 wire (also because it got accidentally whacked in to!).
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
PlaneWood,
A 12 AWG wire, single, in open air actually has a continuous rating of 41 amps.
For multiple conductor use it drops down to 23 amps.
For residential use, 12 AWG is used for a continuous rating of 20 amps. (NEC code)
The wire size is determined for voltage drop, rather than overheating.
The table you are referring to in the later post, refers to electronic equipment wiring, scroll down the page and read the notes.
Edited 8/17/2005 11:47 pm ET by Willie
Not sure where you're getting your info but 12 AWG wire is rated at 20 amps and 10 AWG wire is rated at 30 amps. As it is good practice not to loat the circuit at more than 80% of capacity, you can run a motor rated for 16 amps on #12 wire and 24 amps on #10.
Also, the wire should be rated for running amperage, not startup amperage. Howie.........
>> Actually runs at about 12 to 15 amps
I'll bet it's closer to 12 amps than 15 amps. BTW, who is the manufacturer?Howie.........
Thanks everyone for getting into this topic!Now, what can I use to run my 220V, 25 amp (peak) 8" monster Powermatic PJ882 jointer, that will be about 15 feet from the wall?
Go to HD or Lowe's, buy a 12 gauge extension cord that's designed for a dryer? Will the plugs fit the Powermatic jointer? Or make one from scratch?I hope there's a mobile base for this big puppy or I'm in trouble.Gary
Something that hasn't been asked yet is what size circuit breaker is being used for the existing dryer outlet? I'm guessing it's probably 20 amps but we need to make sure on that first.
Make sure your dryer outlet is grounded. If it's the old three prong style receptacle it may not be, but if it's the modern four prong style it should be grounded (but check it anyway - there's no guarantee that whoever put it in actually connected up the ground.) For your jointer you'll need the two hot wires and a ground wire; make sure you use the ground and not the neutral wire. If there isn't a ground wire in the dryer receptacle you'll have to rewire from the outlet to the panel.
If the jointer has a 2hp, 220volt single phase motor, according to my NEC code book the full load amp rating is going to be about 12 amps. That means when the jointer is up and running, at full load it will draw 12 amps. It will draw more than that for a brief period when it's first started up, but you size the circuit according to the full load rating.
Anyway, a 20 amp circuit would be appropriate for the jointer. It *may* work on a 15 amp circuit, but that's cutting it close and you'd probably get nuisance trips on startup.
For a 20 amp circuit, #12 gauge wire is appropriate. The only reason to go to a larger gauge would be if your cord was very long (say 75 feet or more) to reduce voltage drop.
So, to make an extension cord you need a piece of #12 two conductor with ground cable of the appropriate length, a plug to match the dryer outlet for one end of the cable, and a receptacle to match the jointer plug for the other end of the cable. If it were me, though, I'd consider getting rid of the cord that came with the jointer (assuming it did come with one) and simply making a longer power cord that will reach right from the jointer to the dryer outlet. You said you will be using the jointer about 15 feet from the wall, so a 20 or 25 foot cord would probably be okay, and then there'd be one less connection to come loose in the middle.
Again, make sure you properly identify and connect the hot wires and ground connections, both at the outlet and at the jointer.
Edited to add: To make sure I'm clear, when I say "two conductor with ground" cable, there actually are three wires inside - two insulated ones for the hot connections, and a bare one for the ground.
Edited 8/18/2005 2:19 pm ET by Stuart
If you go back to the first responce to the question you will see that I asked both the questions you note. They've never been definatively answered, however.
I also recommend exactly the same thing you are recommending.
You are correct, whenever these electrical questions come up there is more mis-information than correct information that get generated.Howie.........
#6 wire!! My god. The wire supplying the dryer is only 8 ga. An 8" jointer can't have more than a 3 horse motor. At 220v that makes the draw 16 to 18 amps. 12 gauge will easily handle that, if the run is over 50' consider using 10 gauge. If you look on the second or third page of most power tool instruction books it tells what the maximum cord lengths are for various amperage/ wire gauge combinations.
There are 220 extension cords, in fact there is just about any type of cord you can imagine (I once rented 100 amp three phase cords) But you will not find a cord with a dryer plug on one side (dryer plugs are ony used for dryers) and a 15 amp 220 on the other (that is most likely what your jointer has). They are easy to make. Get a book on wireing at your local big box or library. If you still can't make sense out of it try calling an electrician. But I think that you will have a hard time getting one to come out to make an extension cord! :-)
Also you dont need "two hots and a comon" . In a 220 circuit the common is unused two conductor with ground is correct.
Mike
Edited 8/17/2005 11:51 pm ET by mudman
Look at the previous discussion here.
Edited 8/17/2005 6:53 pm ET by Willie
This thread does really make for a chuckle. First, when you go to 220v, the current drops in half. I don't know how many people think, wow, 220v, I better go with 10 gauge or something. It is the voltage drop that you are concerned about and the inrush is of little concern at reasonable distances (and no, the breakers do not trip instantaneously. I can attest to that as it take sometimes minutes for my breakers to trip when I load up with too many things at once. I'm not talking about my jointer ciruit but those pesky 110v circuits that I can load up with vacuums, belt sanders and lights all at the same time!) So with half the current for a given load, the voltage drop between the source and the tool will be half as much for the same size wire. I've measured my 8 inch jointer current and it almost never goes above 10 amps (at 220v) under full load. BTW the "idle" current is about 5 amps. Now I resist taking those big old 1/8" cuts that the book says, and you should too. I usually take about 1/32" as I hate to waste wood that I don't need to take off.
So even though a 14 gauge wire will work, I'd get a 12 gauge extension cord which always seems to be cheaper than the wire by itself at HD or Lowes, cut the ends off and put on the ones you need. I used an extension cord for a while (how about 3 years) of about 40 feet of 12 gauge and never a problem of any kind! The breaker on that circuit is a 15 amp. It's never tripped either.
I've wired up several shops and had everything from 110/220 single phase to three phase. If the motor is 2hp there is no way it will need more than 12/3 line cord. I would also wire up to the distribution panel directly, if you twin off the dryer outlet, you run the risk of tripping the breaker if both are running or started at once. Also, I really doubt a 20 amp breaker would trip due to in-rush surge on a 2 hp motor, but the difference in price between a 20a and 30a is pretty small so go for the 30a.
my dryer outlet ...
Yep.. Sounds like trouble to me!
Ya half-way into a cut on this really expensive stick and the little lady wants to dry her robe..
Pulls the plug and puts her drier back on line...
2nd problem is that dryer outlet has two hots and a neutral (3wires normally) and the dryer is grounded separately to the circuit.
Cutting this expensive stick while concentrating on doing everything right and then you get this tingling feeling coming through the table of the saw, as current starts flowing through your sweaty hands.
If the dryer circuit is 3-wire, and if it originates at the main panel, and that panel is the service equipment (where the grounds, neutrals, and bonding conductors all meet), then the only difference between the dryer receptacle neutral conductor and an equipment grounding conductor is the color of the insulation - white for neutral, green or bare for ground, unless it's SE cable, in which case, the neutral is bare stranded.
Technically, the dryer receptacle is a 3-pole, 3-wire, 125/250V non-grounding device (NEMA 10-30R), but the neutral is connected in the panel directly to the very same place an equipment grounding conductor would be connected if the receptacle were changed to a 2-pole, 3-wire 250V (only) grounding type (NEMA 6-30R). When using a 240V tool on it, there will be no current flow on the grounded conductor, just like any other 240V receptacle, so risk of voltage other than zero (relative to earth) at the frame of the tool is the same as any other receptacle.
If the dryer circuit originates at a subpanel, then there could be more than zero volts on the ground because it's connected to the neutral bus, which is isolated from the ground bus until they meet at the service equipment (typically the main panel), and when current flows on the neutral bus (and it's conductor, all the way back to the main panel), it will no longer be at zero volts. That's what happens with 3-wire clothes dryers and ranges, and that's why they've been disallowed by the NEC since 1996 for new installations - with current flowing on the neutral, and the frame bonded to the neutral to act as a ground, the frame is not at zero volts.
Because it works under certain conditions doesn't mean it doesn't violate a few provisions of the NEC, though, so for the record, run a new circuit for the tool(s). It's no harder than running a 120V circuit.
Be seeing you...
Edited 8/19/2005 3:06 pm ET by TKanzler
Agree.
Could not explain it better myself, other than the split phase tapped from the tranny!
Edited 8/19/2005 4:34 pm ET by Willie
Dryers and some other fixtures have a separate ground (As in four wire outlets)..All I know is 220 is two HOT wires wires and a ground..
115 is a HOT AND a neutral! (And sometimes a separate ground wire)I just worked with Machines for the printing industry... Some had 115 Volts and we had a Neutral pulled for that..Now 440 and above I let a expert do it!
Here's my opinion. You pay hundreds of dollars for your tools, you shouldn't be using extension cords, especially on 220V. Run a seperate circuit for each of your 220V tools. If you don't know how to do it by code, DON'T DO IT YOURSELF!! You could eventually cause a fire or severe injury to yourself.
Larry
I love these "watercooler" electrician discussions. Everybody seems to have a different spin on what this poor guys should do, and all he wants is to simply hook up his jointer.
Seriously, would you take anybody's advice here and bet the farm on it? I can see you trying to explain how you got wiring advice from a woodworking news group to the insurance company after the house has burned down.
Just hire an electrician! It will cost very little to do what you want and it will be done correctly.
TDF
There's more discussion going on here than just hooking up a jointer, but apparently it went right over your head.
This forum is about sharing ideas, and learning, but I'm pretty sure everyone here knows how to write a cheque. Thanks anyway for your valuable input.
Walker1
You bet this is a water cooler discussion. That is what all these posts amount too. Except I suppose when some post pics of their work. The origional poster was given a lot of great advice, even though some of us don't agree on what is "better". If the origional poster can't take the information presented and make an educated decision from that......... well then no one can help. I've worked with enough electricians to know that their ideas are not always right on either, especially with wierd stuff like this. And again If you start calling around to find an electrician to make you an extension cord, I think you will find that it is not so easy. Especially since it wouldn't meet code to do so. Or even worse youd get some yahoo with nothing better to do than make extension cords. Around here any electricion worth his salt would never have time for something like that.
Mike
As I have read the NEC, it prohibits designing buldings so that extension cords are part of the permanent wiring. Could you please give the NEC code reference that prohibits extension cords?Perhaps you could read through the UL listings of extension cords and female cord ends and determine what their "legal" uses are.Or you could read the directions on the power tool. Most give approved sizes and lengths for extension cords.
Edited 8/20/2005 6:15 pm ET by GHR
You are right about using extension cords as perminate wireing. But that is not what I am refering to . An extension cord that has a dryer plug (220/110 @ 30amps) on one end and a 220v. 15amp female on the other end is not code. The end result is a 15 amp outlet protected by a 30 amp breaker. I am not saying I wouldn't do it myself if I needed to, but any good electrician would want to install a small subpanel with the apropriate breaker/ outlet combination. that is going to cost at least $500. Of course it is very easy for one to do themself and the materials probably cost $50.
Mike
The breaker is intended to protect the permanent wiring not the device.I believe you are allowed to protect even a #16 extension cord with a 30amp breaker.You appear to have reasonable electrical practices. I find nothing wrong with them. But it would help if you and others would not refer to the NEC for non-NEC issues.
Thanks for the complemint. Nobody seems to agree with any body on electrical issues. I am not an electrician so it takes me forever to look up codes. And even then the NEC almost as ambiguas as the Bible! As I sure you see all the time (even in this thread) people find seemingly contrary passages about the same situation. My knowlage comes from twenty years of trouble shooting redtags. For those who are not familular during a construction or remodel job the city inspectors "red tag" any thing that dosen't meet code. Most of the municipalities I work in are more restrictive than the NEC. I very seldom have electrical red tags any more because I check all my subs work before I call the inspector, hell I do most of th wireing myself on smaller jobs. I frequently find things the inspector misses (they can't check every thing).
This idea that the breaker protects the wireing is not as simple as it sounds. It also protects the outlet, and by association the plug that is conected to it. So it is not code to have a 15 amp outlet on a 30amp breaker for this very reason. I garuntee you having an outlet that dosent match the breaker would get tagged by the inspector. Of course there are industrial situations where it is allowed when the machines hace their own protection. Making an extension cord to get around that code would not fly. I am certian that you could find someone to do it..... but certiantly not the type of electricians I would trust on my projects. Ultimately "code" is what the inspector says it is.
Again If I had to do it I would, but I wouldn't pay some half a$$ed electrician to do it. If your going to start monkeying around with this stuff you should have a decient understanding of it.
Mike
I saw a brass tag on the electric chair once,,, It said 'You can be sure if it's Westinghouse',,,
LOL.
I heard that some where reciently... I'm in Texas where we keep the chairs pretty warm. For better or worse.....
Mike
How did you survive the chair and manage to escape after that?
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