220 hookup to TS--extension cords...safety

[Roy Wall]

How many of you all use a extension cord to your 220 tools....?

Is there a safe limit in length......?

I'm afraid I'd have to go 25' or more.........so am I better off running another line to the garage??

I've search the threads......but didn't see any direct answers-- so sorry if this is more overlap to you pros....

THanks - ROY

[Donnie Raines]

I made several chords out of 12 gauge wire and the appropriate connectors. Never had an issue.

Buddy of mine actually "rewired" the tools with longer chords.....

[Jim Becker]

Both my TS and my BS have short pigtails and use a custom extension cord to the wall...twist locks on everything. The BS (MM16) came that way from the factory and the TS was made that way by me so that I have an easily accessable quick disconnect for blade changing and other maintenance. The outlet is not in a convenient location to do that at the wall. In both cases, the cord is only long enough to do the job and in the situations where I have changed my shop around, the extension was shortened or re-made as appropriate.

There are many folks who are not comfortable with extension cords like this and I respect that. But this was the best arrangement for me and my shop and I've been careful to insure that I use the right materials (properly sized), etc., to meet my goals. I would not do this for long runs, however...a new circuit is warrented, IMHO, for that.

[Don Baer]

Roy;
I think in the end youd be better off just running another circuit. It won't cost you much more then a good extension cord and will be much safer. you can get some EMT, fittings, wire, recepticle and a box at the borg and if you need one a decent bender.

[Chris Padilla]

Roy,

For 240 V stuff, I like to keep the extension cord the same gauge or larger as what's in the wall. After all, consider that from the breaker to the outlet is more or less an "extension" cord, too, right?! :)

However, if you can muster it, do consider putting a couple additional outlets so that your extension cords aren't so long. The good flexible 10/2 + gnd at Home Depot isn't cheap but it is very nice and what you want from an extension cord.

[Richard Wolf]

I'm with Jim, I always make 220 cords to keep my shop flexible. I also am not a big fan of a drop cord to the table saw, it always seems to be in the wrong place. I have found the cheapest way to make them is to purchase heavy duty extension cords, 10 or 12 gauge, and replace the connectors. For some reason this always works out cheaper than purchasing wire off the spools.

Richard

[Roy Wall]

I should note that my BIL works for a major construction firm in our area. He could get (probably) a 40' cord for me. My plan would just to hook it in the dryer slot in the utility room and run it ou to the TS in the garage.

I would have no other connections along the way... Just one cord for one machine...

[Rob Russell]

Roy,

If you're going to take that approach, you should make sure that the current dryer receptacle has 4 wires - (2) hots, neutral and ground. The older 3-wire configuration used the neutral as a ground and you do not want to do that for your machinery. If you have a 3-wire dryer setup, I'd replace the dryer receptacle and pigtail with a new 4-wire setup. You could then buy a plug and wire up a 240v extension cord that only used the 2 hots + ground (vs. 2 hots + neutral).

Rob

[Phil Ordway]

I have an electric motor manual with a chart based on hp, voltage and amps. The length of run in feet is based on distance from main to motor. For example, 3HP 240V with 25' from main to outlet and 25' to motor, requires 12 gauge wire. Sound small? Remember that each line wire carries half the amperage at 240V that an equivalent 120V motor would carry.
You could run an extension from the dryer, but it would have to conform to current code. 240V applications require 2 line wires and a ground - NOT a neutral.
Let me know your numbers and I'll let you know what the manual says.

[Joe Lenox]

Just a quick question?? On my new unisaw the plug that came with it has only 3 prongs, i assume two lines & ? ground or neutral it dosent have both. At the outlet end I have 2 line and a neutral and the netural is hooked to the ground of the outlet. There is a ground wire but its tied to the box (all my wireing is in conduit) Is this correct???

[Larry Reimer]

Roy, I think we all use an extension cord to run 220 volt tools at some time. Be aware of voltage drop which is a function of wire size and length of wire http://www.stanselectric.com/vdrop.html and also try to keep from tripping on the cord and protect it from physical damage.

[Jim Becker]

Just a quick question?? On my new unisaw the plug that came with it has only 3 prongs, i assume two lines & ? ground or neutral it dosent have both. At the outlet end I have 2 line and a neutral and the netural is hooked to the ground of the outlet. There is a ground wire but its tied to the box (all my wireing is in conduit) Is this correct???

240v tools have two hot legs and a ground. There is no "neutral".

[Chris Padilla]

Just a quick question?? On my new unisaw the plug that came with it has only 3 prongs, i assume two lines & ? ground or neutral it dosent have both. At the outlet end I have 2 line and a neutral and the netural is hooked to the ground of the outlet. There is a ground wire but its tied to the box (all my wireing is in conduit) Is this correct???

Joe,

We need a few more questions answered and some clarity to properly answer your second question; Jim nailed the first:

This outlet could be wired correctly--kinda sorta but not really because it depends on from where this outlet is wired. Clear? ;)

(1) Let's make clear that we are talking about a 240 V outlet--NOT 120 V. Correct?

(2) Let's make sure that this 240 V outlet is NOT meant for your electric dryer. Correct?

(3) When you say the neutral is hooked to the ground of the outlet, I'm assuming this is a green screw of some kind or what appears to be a metal strap or metal body of the outlet? Correct?

(4) How many conductors does this outlet want? It should be either 3 or 4 conductors. (This is a trick question because I more or less asked this in (2) above :) )

If you answered "Yes" and "3" (which I think you will), then read on...it will apply. If not, then what I'm saying, while still true, may not apply to this outlet.

If this 240 V, non dryer, 3-conductor outlet is wired from a sub-panel (i.e. not the main panel), then it is incorrect and should be fixed because you have a dangerous situation on your hands! In sub-panels, the whites (neutrals) and the grounds (green and/or bare) are kept isolated from each other. Remove the white (neutral) wire and cap it and tuck it back into the box. Only the red and black and green/bare should be connected to the outlet. Only the green/bare should be connected to the metal box.

If this 240 V, non dryer, 3-conductor outlet is wired from the main panel (i.e. where your meter might be and where you should have a breaker in the 100-200 A size that should kill power to the entire house), the neutrals and grounds all tie together--but only at the main panel! So, technically, if this outlet is wired directly from the main panel, hooking the neutral to the outlet ground and the ground to the metal box is okay but I don't think it really follows the code precisely and therefore needs to be addressed. The neutral and the ground shouldn't really tie together in the outlet box...only at the main panel. I think any electrical inspector worth a bean would mandate that this be fixed.

Well, there you go...hope it makes sense. :)

[Rob Russell]

Joe,

We need a few more questions answered and some clarity to properly answer your second question; Jim nailed the first:

This outlet could be wired correctly--kinda sorta but not really because it depends on from where this outlet is wired. Clear? ;)

(1) Let's make clear that we are talking about a 240 V outlet--NOT 120 V. Correct?

(2) Let's make sure that this 240 V outlet is NOT meant for your electric dryer. Correct?

(3) When you say the neutral is hooked to the ground of the outlet, I'm assuming this is a green screw of some kind or what appears to be a metal strap or metal body of the outlet? Correct?

(4) How many conductors does this outlet want? It should be either 3 or 4 conductors. (This is a trick question because I more or less asked this in (2) above :) )

If you answered "Yes" and "3" (which I think you will), then read on...it will apply. If not, then what I'm saying, while still true, may not apply to this outlet.

If this 240 V, non dryer, 3-conductor outlet is wired from a sub-panel (i.e. not the main panel), then it is incorrect and should be fixed because you have a dangerous situation on your hands! In sub-panels, the whites (neutrals) and the grounds (green and/or bare) are kept isolated from each other. Remove the white (neutral) wire and cap it and tuck it back into the box. Only the red and black and green/bare should be connected to the outlet. Only the green/bare should be connected to the metal box.

If this 240 V, non dryer, 3-conductor outlet is wired from the main panel (i.e. where your meter might be and where you should have a breaker in the 100-200 A size that should kill power to the entire house), the neutrals and grounds all tie together--but only at the main panel! So, technically, if this outlet is wired directly from the main panel, hooking the neutral to the outlet ground and the ground to the metal box is okay but I don't think it really follows the code precisely and therefore needs to be addressed. The neutral and the ground shouldn't really tie together in the outlet box...only at the main panel. I think any electrical inspector worth a bean would mandate that this be fixed.

Well, there you go...hope it makes sense. :)

Chris,

Even if this 240v receptacle were intended for a dryer, because it's a new installation - you can't use a 3-wire setup (i.e., hot/hot/neutral) - you must use a 4-wire setup (hot/hot/neutral/grounding).

It's a code violation to bond the neutral and grounding conductors anywhere but the main panel. It doesn't matter whether this is fed from the main panel or not - the neutral/white conductor would not be used for a machinery receptacle. Disconnect the white/neutral conductor and cap it off. There should be a grounding wire connected to a green screw in the junction box. Pigtail that to the grounding conductor coming from the panel and a third conductor going to the green screw on the receptacle.

Rob

[lou sansone]

hi rob

I guess I am a little confused with what the real question is from roy. I don't have the NEC in front of me for reference so I may have this wrong from memory and experience ( former electrician and a degreed EE ) but for true 220 volt single phase feed that does not use a neutral for any part of the circuit, why would you need to carry a neutral to that load? Where would you hook up that unused neutral? I agree that you would not join it to the ground in the outlet. Take a look at the nema 6-20p or 6-20r 20a 250V where is the neutral in that configuration? For all of my 3 phase machines I don't run a 5 wire circuit, nor have I ever had to unless we were using the neutral for current. I agree that neutrals and grounds should only be joined at the Load Center. Why would it be against code to run two hots and a ground that only serves to ground the equipment ? Like I said, I may not be up to the most recent code, but just wanted clarification.

lou

[Jim Becker]

Lou, I could be wrong, but I think that Rob is saying that if the circuit already has the fourth conductor in it, you need to carry it all the way to the termination point, even though you will not use it for the actual woodworking machine connection. Rob? Am I correct on what you are saying?

[Rob Russell]

I'll respond to a couple of the posts all at once.

Lou (and others) are correct - 220v single phase wiring needs 2 hots + a grounding conductor. There is no need for a neutral.

My point about the 4-wire dryer thing is that the NEC used to allow a dryer hookup where the neutral was connected to the grounding pin. That's not allowed any more - if you replace the circuit it needs to be a 4-wire dryer circuit, not the old 3-wire circuit. So - if the receptacle that is feeding Roy's extension cord is new, then he is fine.

If Roy's dryer outlet is only 3-wires, then he shouldn't use it for his machinery extension cord. That's because the 3-wire dryer outlet is 2 hots + neutral and he needs 2 hots + grounding.

The point about my response to Chris's post with the neutral conductor is that Joe Lenox's post describes the wiring in his receptacle box as having the neutral conductor attached to the grounding hold on the receptacle. That should be corrected.

In terms of continuing 4 wires all the way through a circuit, let's say that you had a 4-wire dryer circuit with 2 hots, neutral and grounding conductors. It's perfectly acceptable to run 2 hots + grounding conductor from there to feed a 240v machinery outlet - no neutral needed and not run.

[Ken Fitzgerald]

Lou.....Rob can correct me if I'm wrong. For 220 you need 2 hots and ground.....in the case of some appliances they use 220 and 110 and therefore 4 conductors....2 hots...ground....and the neutral is used to supply the return for 110 which is acquired from one of the "hots".

[Roy Wall]

I'll respond to a couple of the posts all at once.

Lou (and others) are correct - 220v single phase wiring needs 2 hots + a grounding conductor. There is no need for a neutral.

My point about the 4-wire dryer thing is that the NEC used to allow a dryer hookup where the neutral was connected to the grounding pin. That's not allowed any more - if you replace the circuit it needs to be a 4-wire dryer circuit, not the old 3-wire circuit. So - if the receptacle that is feeding Roy's extension cord is new, then he is fine.

If Roy's dryer outlet is only 3-wires, then he shouldn't use it for his machinery extension cord. That's because the 3-wire dryer outlet is 2 hots + neutral and he needs 2 hots + grounding.

The point about my response to Chris's post with the neutral conductor is that Joe Lenox's post describes the wiring in his receptacle box as having the neutral conductor attached to the grounding hold on the receptacle. That should be corrected.

In terms of continuing 4 wires all the way through a circuit, let's say that you had a 4-wire dryer circuit with 2 hots, neutral and grounding conductors. It's perfectly acceptable to run 2 hots + grounding conductor from there to feed a 240v machinery outlet - no neutral needed and not run.

Rob, will a photo of the dryer receptacle & the cord tell the story? Our house is 11 years old.

[Chris Padilla]

Lou.....Rob can correct me if I'm wrong. For 220 you need 2 hots and ground.....in the case of some appliances they use 220 and 110 and therefore 4 conductors....2 hots...ground....and the neutral is used to supply the return for 110 which is acquired from one of the "hots".

Ken,

A dryer is a good example of needing a 4-conductor wire. Some components of the dryer use 240 V (heating elements, maybe the motor that spins the tumbler, I'm no dryer expert) but some also use half of that 240 V, like the light bulb that turns on when you open the dryer door. As you know most light bulbs are designed for ~120 V.

The neutral is pulled out of the transformer leg (or coil) providing 240 V at half-way down the transformer. Electronic's folks would call it a center tap. If you take a voltmeter and measure one end of the leg with respect to the other leg, you will measure 240 V. If you measure between either leg and the center tap, you will get about 120 V.

At your main panel (or very close to it), a copper rod should be driven deep into the ground. The ground and neutral (center-tap) are tied to this at the main panel. There probably is a ground rod at the large transformer sitting on the power pole or in a dungeon under the ground somewhere.

Hopefully I've address your post adequately. I'm sure Rob will correct any inaccuracies since I'm no NEC expert...I just play one SMC! :p

[Roy Wall]

Here's what receptacle I was thinking about using....

[Chris Padilla]

Looks good, Roy!

[Larry Reimer]

Sometimes it helps to look at it another way. I refer to the website selfhelpandmore.com in their switch/outlet section they'll show how to wire either a 3 wire or 4 wire dryer plug. In their home wiring section they'll show you a lot more.

[Rob Russell]

Looks good, Roy!

Bzzzzttttt! Ding, Ding, Ding!

Sorry Chris - not what Roy wants to use.

That's a 3-wire dryer plug. That means it has 2 hots + neutral. Roy wants 2 hots + ground to be correct. The proper thing to do would be to replace that with a 4-wire dryer circuit. Then he could make an extension cord that used the hot/hot+ground.

Converting that receptacle to a 4-wire setup probably means replacing the cable and since that's a sheetrocked wall, that probably means opening up the wall so you can get to the cable, replacing it and then patching the sheetrock. That would mean replacing the pigtail on your dryer too.

It might be easier just to to run a circuit to the garage.

I'd also like to say that my statement in an earlier post about 220v single phase needing 2 hots + ground applies to motor loads only - I should have been clearer about that. Chris' example of a dryer that has a light inside the drum (or a range with a surface light or clock) are examples of 220v loads that do require a neutral. It's specifically these types of loads requiring the neutral that forced a change in the NEC. Now the NEC sez run the extra conductor but existing installations are grandfathered in.

[Chris Padilla]

Rob,

How can it be a dryer circuit with no ground? I always thought dryers needed 4 conductors...not 3.

[Jim Becker]

How can it be a dryer circuit with no ground? I always thought dryers needed 4 conductors...not 3.

Chris, there was a time when these things were installed with a "shared ground/neutral". In fact, the double wall oven I ripped out during our kitchen renovation in 2003 was setup the same way...too hots and a combined ground/neutral. That's not done "today"...they need to be separate.

[Chris Padilla]

I figured that was the case. My dryer outlet was the same as I recall...I've updated it! :)

[Cecil Arnold]

All this is very interesting, however I think the real answer to Roy's question is IMHO that he needs to run a sub panel to the garage, then give himself the 110-220 outlets/circuts he needs. If you look at the wire size on your 3 hp TS it is relatively small. I would guess 14 ga. A 12 ga extension is more than adiquite for something like that (if kept to a reasonable lenght) and, I think, the same is true for our MM16s. In a 220 circut each hot wire carries half the voltage and amperage. A 15 amp 220 load only pulls 7.5 on each hot side. In a 110 circut a 15 amp load is carried by a single wire. I could be wrong about this, but in Europe, everything is 220v and the wire sizes they use in their houses are about the same size we see on our 220v TSs. I know some are conserned about fire hazards, but they have much less fire loss in most European countries than we do.

[Dave Mapes]

I,d like to jump in here and state that the key this whole question is what phase is required. When phase 1 is required then the 3 wire (2 hot 1 neutual) is used for 1 phase and for 3 phase the 4 wire is used (not sure if it is 3 hot 1 neutual or 2 hot 2 neutual). Since most of our tools require 220 1 phase 20 to 30 amps. (industrial shop are more likely to require 3 phase.)

I recommend you run a several 120 line and 1 or 2 220 phase one with 2 or more outlets per line. I have a TS and DC running off of the same 220 1 phase line with a 30 amp breaker without any problems. Note there is no ground on a 220 line as the neutual acts as the qround from breaker box.

[Chris Padilla]

Dave,

I would hazard a guess that most folks on SMC only have access to single phase power in their residential homes. Three phase is typically reserved for industry and pro shops as you point out.

[lou sansone]

dear all
thanks for clearing up all of that 3 wire and 4 wire stuff;)
I agree with the general intent, and am glad that the NEC no longer allows the ground / neutral to serve as the current carrying conductor in those old style 3 prong plugs

lou

[Kirk (KC) Constable]

Have we seen a picture of the panel? On mine, the neutral and ground wires share the same bar...and I'm just nearly awfully sure that the instructions blessed it. It has been several years since the install, but only a couple since I wired up a new panel in the shop...and at that time, the GE panel was just like the other one. Perhaps his is wired the same way....

[Larry Reimer]

The reason for having a grounding (that's the white wire we call the neutral) conductor and a grounded (that's the green or bare wire we call the ground) conductor is redundancy. A safe electrical system will have a good ground path. By using two separate wires for that ground path we increase the safety of that system.

By code the neutral bar and the ground bar are bonded (tied together) at the source. That makes them the same electrical point. Thus, after you set a transformer the next panel in line will have the neutral and ground tied together (yes, there's all kinds of exceptions). Panels fed from that first panel will have the ground and neutral separated.

Remember the point of having two different wires in the circuit serving as the grounding path is to increase the safety of that circuit.

[Rob Russell]

The reason for having a grounding (that's the white wire we call the neutral) conductor and a grounded (that's the green or bare wire we call the ground) conductor is redundancy. A safe electrical system will have a good ground path. By using two separate wires for that ground path we increase the safety of that system.

By code the neutral bar and the ground bar are bonded (tied together) at the source. That makes them the same electrical point. Thus, after you set a transformer the next panel in line will have the neutral and ground tied together (yes, there's all kinds of exceptions). Panels fed from that first panel will have the ground and neutral separated.

Remember the point of having two different wires in the circuit serving as the grounding path is to increase the safety of that circuit.


Larry,

You've got the grounding and grounded conductors backwards.

The grounded conductor - as in "intentionally grounded" conductor - is what we laymen refer to as the neutral and what is carried on the white conductor.

The grounding conductor - as in Equipment Grounding Conductor - is the safety grounding conductor and is what is carried on the green or bare conductor.

Rob

[Rob Russell]

I,d like to jump in here and state that the key this whole question is what phase is required. When phase 1 is required then the 3 wire (2 hot 1 neutual) is used for 1 phase and for 3 phase the 4 wire is used (not sure if it is 3 hot 1 neutual or 2 hot 2 neutual). Since most of our tools require 220 1 phase 20 to 30 amps. (industrial shop are more likely to require 3 phase.)

I recommend you run a several 120 line and 1 or 2 220 phase one with 2 or more outlets per line. I have a TS and DC running off of the same 220 1 phase line with a 30 amp breaker without any problems. Note there is no ground on a 220 line as the neutual acts as the qround from breaker box.

Dave,

To correct something in your post - a 220v circuit requires 2 hot + a grounding conductor - not 2 hots + neutral. The problem is with older dryer circuits that were wired as 2 hots + neutral and that doesn't meet code to run a new machinery circuit.

Rob

[Larry Reimer]

Rob, you are absolutely right. and thank you for correcting that.

[JayStPeter]

Have we seen a picture of the panel? On mine, the neutral and ground wires share the same bar...and I'm just nearly awfully sure that the instructions blessed it. It has been several years since the install, but only a couple since I wired up a new panel in the shop...and at that time, the GE panel was just like the other one. Perhaps his is wired the same way....

I'm with you KC. I think Roy can get by safely just using his current circuit. Lets think about the reality here. Roy will be using 3 wires to his saw. Does he need a 4th (not connected) wire that connects to the same place in the panel as the 3rd to run it safely? :confused: Maybe if he puts a green screw on it, the 3rd wire becomes a ground instead of a neuteral?

If the saw had a 4th safety ground connection I would feel differently. But, once you bypass a wire, it's useless ... period.

Jay