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toolmaker76
09-06-2010, 12:20 AM
Have been restoring an old lathe and mill/ drill in my shop. Both were originally set up for 120 volts, but as I put the motors back on them, I see diagrams that tell me that they can also be wired for 240.

Since I didn't have to change anything else around I went ahead with the 120 wiring, but I have to wonder before I get too much further- would there be a big advantage to going with 240?

A disadvantage would be running power to them, but as I just got power to the shop and am still in process of running wires and outlets it is not a huge issue. I would think, for example, that a 1 horsepower motor would be the same regardless of voltage, and I know there is a ratio. Twice the voltage would be half the amperage, but I am not enough of an electrician to process it any further than that.

Just wondered what were the thoughts or experience that others have had? Neither machine is huge. Thanks.

Richard-TX
09-06-2010, 12:25 AM
In most cases converting to 220 isn't worth it.

chipmaker4130
09-06-2010, 12:40 AM
If you're just now wiring the shop, I think I would go with 240. If you use at least 12ga wire and an appropriate breaker, you'll be able to use a lot bigger motors in the future with no further changes. You might also notice slightly quicker starts on your current equipment after switching to 240. At this point it doesn't sound like you'd be converting anything except your plan!

darryl
09-06-2010, 01:12 AM
As you said, running on 240 is going to cut the current in half. That will mean less voltage drop in the wiring, so more of the available voltage will be used by the motor, starting and running. As said, starts are quicker.

It may not be any consequence to you, but dimming of the lights will be less during startup.

My opinion- if you're in the middle of it all now, don't hesitate to wire up for 240, and use four wire. You can always rewire the outlet box for duplex 120 later on if things change, but you can't easily go from 120 to 240 unless you pulled in the appropriate wire from the start.

You can always draw an amp or so for a light or a DRO from either hot leg to neutral, so it's not as though you have to do without a source of 120 at the same spot.

Black_Moons
09-06-2010, 03:33 AM
Depends on the HP, if its a 1HP motor, it should be fine on 120v, little light diming but oh well.

If its 1.5HP, it could go on either 120v or 240v, its about the limit for 120v circuit

If its 2HP, it needs a 20A 120v circuit to run, not very common to find a plug like that in most shops and will likey brown the hell outta your lights on turnon. Might as well upgrade to 240v, as then you can still use a standard 14/2 romex run to power it. (15A 240v circuit) Might be usable on a 15A 120v circuit but will likey blow the breaker when you load it.

MrDan
09-06-2010, 08:06 AM
If you're just now wiring the shop, I think I would go with 240. If you use at least 12ga wire and an appropriate breaker, you'll be able to use a lot bigger motors in the future with no further changes. You might also notice slightly quicker starts on your current equipment after switching to 240. At this point it doesn't sound like you'd be converting anything except your plan!

+1 for 240. I've never been sad that I planned for growth. With 240 already there, you can slap on a VFD and run 3 phase motors. With 120, you're really limited in what you can add later.

Tony Ennis
09-06-2010, 09:32 AM
Electricians* ran a 60a 240v to my shop's breaker box specifically so I could run a VFD and a small 3 phase motor on my lathe. Running more power than I could imagine using cost me about 20% more. Wife's been talking about an addition for her sewing/quilting/yarn room. Now there's power if she pulls the trigger.





* The wife thought about me running electricity indoors for about half a second before vetoing it. :D

airsmith282
09-06-2010, 10:04 AM
from what i know about this stuff, here is my 2 cents

in a welding machine 240 is better cause you will get more arc volts at the same amp setting as in 120 volt.

yes you get faster start ups, and in theory you will draw less amps on say a lathe or mill running 240,

now in the house we went all florcent lights we didnt save alot on the hydro. but we did get rid of the big fridge and went smaller and we got rid of the stove and went 120 volt convectoin oven , and of course we have a micro wave , and we use a butuan stove thing for boiling water making soup etc,

our hydro bill went from 140.00 to now 67.00 a month and my shop lights are all flocent and never shut off, out hose lights are only on when we need them and the tv and both laptops run for several hours a day ..

i personal find running everything on 120 volt the advantage, for the amount of welding i do i now also only use 120 volt welders, and got rid of my big welder i was not using it at all anyhow, the welding jobs i get my flux welder can more then handel..

any how if switching to 240 will make things work better in the big picture then switch if its not going to offer an advantge then leave things as they are,
even my house furnace runs 120 volt and draws very little amps,

Forrest Addy
09-06-2010, 10:24 AM
Here's the big point of runnng 240. You're a guy. You will get more powerful machine tools as time passes and your capabilities evolve.

120 V limits connectable motor HP to 1 1/2. With 240 you can connect 5 HP single phase (the biggest single phase motor commonly stocked). Then there is welding and plasma cutting equipment. Sum the potential load and a 60 Amp service may be a little pinched - what happens when you strike an arc or atart the lathe about the same time the compressor kicks in? The only thing that saves the typical small shop owner ftom electrical overload is he can only run one thing at a time.

And there may very well be a three phase motor driven item in your future. That means a rotary phase conveter or a VFD (VFD's are fascinating and very handy gedgets; read up on them). The biggest 120V VFD is 1 HP. There are single phase 240 V rated VFD's to 3 HP and three phase input rated to humongous.

Nope. Better run your 240 circuits while you can. One for each likely machine tool staton and one each for welder and compredsor.

While we're on the subject. Now is a good time to standardize on 240 Volt plugs and receptacles. A wise suggetion was made earlier: run 240 V 4 wire (240 plu a neutral and ground.) There are standards for plugs and receptacles to preclude accidently plugging equipent of one volage into a receptacle connected to a different voltage. My mistake when I wired my shop was I ran 240 V and ground omitting the neutral. Many 240 volt machnes need 120 Volts for lights, feed units, or convenience outlets and the neutral is necessary for current return to the panel. You can't legally use the ground as a current return. The ground's sole function is fault current to open the circuit protection. Anyway, I cheat and use the ground for 120 V but I shouldn't. But I didn't run a neutral. (Where's the a$$ kicking machine?)

I suggest you wire for 230 V 30 Amp and use NEMA 14-30 (30 amp rated straight bladed) or L 14-30 (twist lock 30 Amp). This provide the neutral you need for incidental 120 V loads. These plug and receptacles aren't cheap but it's a one time expense to do things right. You can save bundle by buying these NEMA devices on eBay. Here' a link:

http://business.shop.ebay.com/i.html?_nkw=Nema+l14-30&_sacat=12576&_odkw=Nema+14-30&_osacat=12576&_trksid=p3286.c0.m270.l1313

KiddZimaHater
09-06-2010, 10:47 AM
I have converted my mill, lathe, and bandsaw to 240.
My lathe is wired directly to a kill switch and VFD.
I also have an outlet which I can plug my mill, welder, or bandsaw into.
240 seems to run alot smoother than 110. Especially at start-up.
240 draws less amps.
I also standardized all of my plugs, so everything is using the flat-blade style plug.

lakeside53
09-06-2010, 11:06 AM
.... You can't legally use the ground as a current return. The ground's sole function is fault current to open the circuit protection. Anyway, I cheat and use the ground for 120 V but I shouldn't. But I didn't run a neutral. (Where's the a$$ kicking machine?)



I know Forrest knows why what he did is wrong.. but some don't.

If you use ground as a 120v return path, nothing can hurt you UNLESS the ground path is interrupted before the panel. If it is, your machine iron (and anything else wired upstream on that circuit) now sits at 120 volts waiting for you or you kid to grab it...

How can this interruption happen to a mchine if the wall socket is wired correctly? Easy.. plug your machine into an extension cord... you know.. the old pos that's been run over in the garage for 10 years, and has has a broken off ground pin...


There are many other ways... and someone in another part of the house can be zapped while working on wiring or whatever. I HATE untwisting a wall socket ground wire bundle and seeing an arc -that almost always means something upstream has been wired to ground.


A common source of "wired to ground" is panel lights particularly neons. Current is low but..

Million of grandfathered stoves are still wired as 2 wires plus ground, and use ground as a return. I moved one recently for a neighbor - the ground wire has corroded to a hair. Nice...

I will never wire ground as a return path... and when I find one (not so uncommon..) I track it down a remove the offender over any objection, or leave.

metalmagpie
09-06-2010, 01:32 PM
The biggest 120V VFD is 1 HP.

Uh, nope. 1.5 horse, not 1 horse. Got an A-B Powerflex 1.5hp VFD right here which runs on 120VAC. No kidding.

metalmagpie

metalmagpie
09-06-2010, 01:41 PM
If you use ground as a 120v return path, nothing can hurt you UNLESS the ground path is interrupted before the panel. If it is, your machine iron (and anything else wired upstream on that circuit) now sits at 120 volts waiting for you or you kid to grab it...

How can this interruption happen to a mchine if the wall socket is wired correctly? Easy.. plug your machine into an extension cord... you know.. the old pos that's been run over in the garage for 10 years, and has has a broken off ground pin...

I'm with you. Almost. I know of at least two guys who made carts for their 240VAC stick welders. Those carts had 220 wire run from the wall to a box. The welder AC lead was trimmed so it plugged or was wired to that box. Also on that cart was another J-box which had 2 117VAC outlets. One was wired between L1 and ground and the other was wired between L2 and ground. This is cheating.

Ok, following your example: you have this setup out in your driveway where you're welding up something. You plug in your POS extension cord which has the ground pin cut off of the plug. The other two leads of the extension cord, however, are still connected to L1 and GND. So yes it's cheating, but how does that make my grinder body go to 117V?

I'm *not* saying it's safe. Nor to do it. But I just don't follow how your scenario kills someone.

metalmagpie

Forrest Addy
09-06-2010, 02:55 PM
Me and my big mouth. I got the guilties over my "no neutral using ground as current return" laziness. Now I'm sorting through my junky control traneformer collection to find a couple of 1.5 KVA to mount on the lathe and mill for 120 convenience outlets.

The mill is a particular problem. I need outlets for 3 feed units, the DRO, the slotter head, two for the machine lights, and a couple spares. Add the transformer and the back side of the mill column is gonna be a spaghetti factory.

metalmagpie. Yep. I went and looked are a 1 1/2 HP 120 input VFDs and there they were. Must be newer than a couple years ago which was the last time I went looking. I used a 1 1/2 HP Teco and a step-up transformer which added 30 lb to a gadget that was supposed to be portable.

lakeside53
09-06-2010, 02:57 PM
MMP :A machine body does not go to 117 unless you have connected something (even as "insignificant" as a power indicator lamp) between 117 and ground AT the machine (or have a fault in the machine) and that ground back to the panel is lost. If there is a voltage source to the part you touch, and you use that pos extention cord, you can die - you are providing the return path to the panel via ground.

Leakage to ground on an old single insulated grinder can often unnoticed until you use that bad cord...

HOWEVER, in your specific case which is not exactly what I was refering to, unless the welder ground to the panel is lost, your grinder won't zap you... With the bad cord, you do not however have any protection against a fault in the grinder applying potential to the exterior metal (assumption) case.

BTW, that welder setup isn't "cheating", it's plain unsafe... Lose the welder ground connection and... And.... if you have two devices plugged into the 117 using your L1/L2 example, you can end up with 220v accross one of them (the lower powered unit...). Great.

lakeside53
09-06-2010, 02:59 PM
The mill is a particular problem. I need outlets for 3 feed units, the DRO, the slotter head, two for the machine lights, and a couple spares. Add the transformer and the back side of the mill column is gonna be a spaghetti factory.


Heck, look on the bright side; you can now add a contactor and have a single power off for the mill and all that spaghetti :D

lakeside53
09-06-2010, 03:12 PM
Uh, nope. 1.5 horse, not 1 horse. Got an A-B Powerflex 1.5hp VFD right here which runs on 120VAC. No kidding.

metalmagpie

yes.. there are several other types up to 1.5hp.

tlfamm
09-06-2010, 05:25 PM
In reply to Lakeside53:

>>>Million of grandfathered stoves are still wired as 2 wires plus ground, and use ground as a return. I moved one recently for a neighbor - the ground wire has corroded to a hair. Nice...


Do I recall correctly that the NEC was modified several decades ago to allow running a separate neutral, of appropriate ampacity, to a grandfathered stove to bring it into compliance?

(As opposed to running new 4-wire cable ...)

gnm109
09-06-2010, 06:18 PM
I know Forrest knows why what he did is wrong.. but some don't.

If you use ground as a 120v return path, nothing can hurt you UNLESS the ground path is interrupted before the panel. If it is, your machine iron (and anything else wired upstream on that circuit) now sits at 120 volts waiting for you or you kid to grab it...

How can this interruption happen to a mchine if the wall socket is wired correctly? Easy.. plug your machine into an extension cord... you know.. the old pos that's been run over in the garage for 10 years, and has has a broken off ground pin...


There are many other ways... and someone in another part of the house can be zapped while working on wiring or whatever. I HATE untwisting a wall socket ground wire bundle and seeing an arc -that almost always means something upstream has been wired to ground.


A common source of "wired to ground" is panel lights particularly neons. Current is low but..

Million of grandfathered stoves are still wired as 2 wires plus ground, and use ground as a return. I moved one recently for a neighbor - the ground wire has corroded to a hair. Nice...

I will never wire ground as a return path... and when I find one (not so uncommon..) I track it down a remove the offender over any objection, or leave.

Hmmmmm. Something in this thread made me think of the wiring specified for my Miller Syncrowave 200. It requires L1, L2 and Ground. This is typical for a welder.

On the front panel of the machine, there are two panel mounted 10 amp 115 (nominal, Miller's term) VAC connectors. There is also a 115 VAC feed to the fan motor which switches on when the machine is getting hot.

I looked closely at the schematic in my technical service manual for the machine and there is no neutral.....anywhere. How do the welding machine manufacturers do it? The machines must meet code or they couldn't sell them.

darryl
09-06-2010, 06:31 PM
110 available on the front panel? Probably not live unless the welder is turned on. Probably comes from a tap on the 220v primary winding.

chipmaker4130
09-06-2010, 06:37 PM
[/b]

Hmmmmm. Something in this thread made me think of the wiring specified for my Miller Syncrowave 200. It requires L1, L2 and Ground. This is typical for a welder.

On the front panel of the machine, there are two panel mounted 10 amp 115 (nominal, Miller's term) VAC connectors. There is also a 115 VAC feed to the fan motor which switches on when the machine is getting hot.

I looked closely at the schematic in my technical service manual for the machine and there is no neutral.....anywhere. How do the welding machine manufacturers do it? The machines must meet code or they couldn't sell them.

A welder's main component is a transformer. Transformers can have a variety of 'taps' for a variety of uses. Yours might use this approach.

I see Darryl hit 'go' before I even finished typing!

gnm109
09-06-2010, 07:09 PM
110 available on the front panel? Probably not live unless the welder is turned on. Probably comes from a tap on the 220v primary winding.


Yes, of course. It comes from a tap. And, of course, the sockets are only live when the machine is on. My point is......there is no neutral.


.

Too_Many_Tools
09-06-2010, 07:58 PM
Here's the big point of runnng 240. You're a guy. You will get more powerful machine tools as time passes and your capabilities evolve.

120 V limits connectable motor HP to 1 1/2. With 240 you can connect 5 HP single phase (the biggest single phase motor commonly stocked). Then there is welding and plasma cutting equipment. Sum the potential load and a 60 Amp service may be a little pinched - what happens when you strike an arc or atart the lathe about the same time the compressor kicks in? The only thing that saves the typical small shop owner ftom electrical overload is he can only run one thing at a time.

And there may very well be a three phase motor driven item in your future. That means a rotary phase conveter or a VFD (VFD's are fascinating and very handy gedgets; read up on them). The biggest 120V VFD is 1 HP. There are single phase 240 V rated VFD's to 3 HP and three phase input rated to humongous.

Nope. Better run your 240 circuits while you can. One for each likely machine tool staton and one each for welder and compredsor.

While we're on the subject. Now is a good time to standardize on 240 Volt plugs and receptacles. A wise suggetion was made earlier: run 240 V 4 wire (240 plu a neutral and ground.) There are standards for plugs and receptacles to preclude accidently plugging equipent of one volage into a receptacle connected to a different voltage. My mistake when I wired my shop was I ran 240 V and ground omitting the neutral. Many 240 volt machnes need 120 Volts for lights, feed units, or convenience outlets and the neutral is necessary for current return to the panel. You can't legally use the ground as a current return. The ground's sole function is fault current to open the circuit protection. Anyway, I cheat and use the ground for 120 V but I shouldn't. But I didn't run a neutral. (Where's the a$$ kicking machine?)

I suggest you wire for 230 V 30 Amp and use NEMA 14-30 (30 amp rated straight bladed) or L 14-30 (twist lock 30 Amp). This provide the neutral you need for incidental 120 V loads. These plug and receptacles aren't cheap but it's a one time expense to do things right. You can save bundle by buying these NEMA devices on eBay. Here' a link:

http://business.shop.ebay.com/i.html?_nkw=Nema+l14-30&_sacat=12576&_odkw=Nema+14-30&_osacat=12576&_trksid=p3286.c0.m270.l1313

Good post.

You will not regret wiring for 220V.

TMT

J Tiers
09-06-2010, 09:31 PM
Yes, of course. It comes from a tap. And, of course, the sockets are only live when the machine is on. My point is......there is no neutral.


.

No OVERALL neutral, but there IS a neutral

because with a new separately derived source, you have a neutral from the transformer winding to the outlet. That is the current path.

And, that "separately derived source" has it's neutral bonded to ground at the welder.

Note that that is NOT THE SAME as using a ground as neutral, because the current originates at and returns to the transformer. The ground is a non-current carrying conductor except in a fault condition, which is perfectly correct.

gnm109
09-06-2010, 09:44 PM
No OVERALL neutral, but there IS a neutral

because with a new separately derived source, you have a neutral from the transformer winding to the outlet. That is the current path.

And, that "separately derived source" has it's neutral bonded to ground at the welder.

Note that that is NOT THE SAME as using a ground as neutral, because the current originates at and returns to the transformer. The ground is a non-current carrying conductor except in a fault condition, which is perfectly correct.


I'm not clear on your description here. Please define "new separately derived source".

The welder has only three wires feeding it: L1, L2and ground. Are you referring to some other wire? The schematic shows only L1, L2 and ground.

Which transformer?

J Tiers
09-06-2010, 10:01 PM
I'm not clear on your description here. Please define "new separately derived source".

The welder has only three wires feeding it: L1, L2and ground. Are you referring to some other wire? The schematic shows only L1, L2 and ground.

Which transformer?
Inside the welder is a transformer (generator for a gasoline powered welder). One of the outputs will be the 120V circuits, if there are any.

They are ISOLATED from the incoming line, and are thus "separately derived"..... they don't come directly from the power cord, but from a winding on the transformer which is not "conductively connected" to the input.

they are required to be bonded to ground for safety, just as your power service is.

But the 120V current comes from the transformer winding, goes to the outlet and load, and returns via a "neutral" to the transformer. it never goes through ground.

that "neutral" wire is also "bonded" to the welder ground for safety. But it does not put any current through ground

gnm109
09-07-2010, 09:54 AM
Inside the welder is a transformer (generator for a gasoline powered welder). One of the outputs will be the 120V circuits, if there are any.

They are ISOLATED from the incoming line, and are thus "separately derived"..... they don't come directly from the power cord, but from a winding on the transformer which is not "conductively connected" to the input.

they are required to be bonded to ground for safety, just as your power service is.

But the 120V current comes from the transformer winding, goes to the outlet and load, and returns via a "neutral" to the transformer. it never goes through ground.

that "neutral" wire is also "bonded" to the welder ground for safety. But it does not put any current through ground


Terrific explanation. Thanks. The schematic shows this. It can be confusing. LOL.

I built a large powdercoating oven (2 X 3 X 6'). I used four wire connection. L1, L2, neutral and ground. I use the neutral for 120 VAC to power the coil for the definite purpose contactor, neon lights for the panel and interior lights. It works very well.

The code for new devices, other than welders apparently, requires four wires. Thanks. :)

lakeside53
09-07-2010, 11:42 AM
Code doesn't require 4 wires for all 220 devices. If a new 2+G wire device uses a transformer to provide local output of other voltages, that's fine also. It's the same for welders as other devices - no return other than fault currents though the ground connection. That's basically what Forrest is doing when rewiring his mill and lathe

chipmaker4130
09-07-2010, 03:17 PM
For some, confusion exists about the 'neutral' itself. It is not a separate conducter strung out from the power plant, its just a center tap on the local transformer output.

Arcane
09-07-2010, 08:24 PM
Depending on the soil conditions the electric utility may or may not string a neutral conductor in conjunction with the phase conductor/conductors. Many times the earth itself is used as the neutral if it's resistance is low enough. Often you will see neutrals strung from step down substations on distribution lines, especially in urban situations. Those neutrals are current carrying conductors that are grounded in many many places and are supposed to be at earth potential. Cutting one of those neutrals open to do any sort of work on it is only allowed if you jumper around your work site since there is always the chance of considerable difference of potential across the cut .

gnm109
09-08-2010, 10:38 AM
Depending on the soil conditions the electric utility may or may not string a neutral conductor in conjunction with the phase conductor/conductors. Many times the earth itself is used as the neutral if it's resistance is low enough. Often you will see neutrals strung from step down substations on distribution lines, especially in urban situations. Those neutrals are current carrying conductors that are grounded in many many places and are supposed to be at earth potential. Cutting one of those neutrals open to do any sort of work on it is only allowed if you jumper around your work site since there is always the chance of considerable difference of potential across the cut .


That makes sense. My house has three large conductors coming in from the high voltage transformer on a pole out back. Those would be L1, L2 and ground. Thus, if there were a neutral from the power company, it would have to be somewhere else.

My 200 amp house panel has a neutral bus which provides the neutral to all of the circuits but I'm not sure where it starts since there are only the three wires coming in. It appears to be tied to the ground as well inside the box. It must work since it's been there that way for 33 years. :)

lakeside53
09-08-2010, 11:19 AM
Those are almost always L1, L2 and Neutral. The ground is supplied via a connection at your panel, and another at the transformer.

Neutral is taken back to the tranformer at the local connection. At that point it's connected to ground.

gnm109
09-08-2010, 11:21 AM
Those are almost always L1, L2 and Neutral. The ground is supplied via a connection at your panel, and another at the transformer.

Neutral is taken back to the tranformer at the local connection. At that point it's connected to ground.


You're sure about that....? LOL.....:D

lakeside53
09-08-2010, 11:22 AM
Let's just say it would be rare for it not to be ;)

Arthur.Marks
09-08-2010, 12:47 PM
That's how it is here. Three quite large wires in -- one marked Neutral and color coded white that contacts the shared "grounding" terminals in the main box. The "grounding" terminals also share a connection that literally is "ground" (a metal rod inserted through the foundation of my home and into the soil beneath). The metal rod ("ground") is located just below my main breaker box. Standard residential wiring, suburban location near Chicago.

Don Young
09-09-2010, 12:35 AM
The third wire on the power company drop is definitely a "neutral". It can also be called a "ground" since it is at essentially ground potential and is connected to grounding rods at various places, including at the customer meter or breaker panel. Until you get past the main service panel, the functions of "neutral" and "ground" are somewhat ambigious. The "neutral" carries any unbalance current to and from the transformer and there are some "grounds" connected to it from ground rods and/or coils on the bottom of the poles. The real distinction is that a "neutral" can be expected to carry current under normal operating conditions while a "ground" only carries currents which should not exist, such as leakages and short circuits.

Although connected together in the main service panel, from that point to the point of use the functions of "ground" and "neutral" are assigned to separate conductors. Many people, including electricians and engineers, use the terms interchangeably and this can lead to confusion.