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JoeLee
02-28-2011, 02:56 PM
I've grown tired of dragging around power cords to my various machines so I'm in the process of running a separate 220 line to a wall close to where my lathe and mill are. Looking at my diagram I have an existing 110v line in conduit with a couple 4" boxes at either end. I have a 220v disconnect box mounted on that wall also, that was originally for the welder which found another spot in the shop. I'm going to pull 2 #12's and a ground from the main panel off a breaker to the disconnect box and fuse it at 20 amps. I'm going to run the 220 wires through the existing conduit that houses the 110v wires and drop a box off that conduit for the 220 outlets. No problem doing that as it's not a code violation. This saves me the trouble of running a separate conduit. What I want to do from there is run a 4 conductor extension cord to my lathe with a 220v receptacle and a 110v receptacle for the light and DRO's. Now....... there is a couple ways to do this. the first way is just to take one leg of the 220 line and ground and you have your 110. Done with 3 wires. Altough not reccomended and not to code we have all seen it done before. Technically there should be a nuetral wire there for the 110v outlet.
So what I want to do is just grab a neutral from the 110v line that is right there and use it. An electrician friend said no.... I should run the nuetral back to the main box. So that means I have to run 80 feet of nuetral just for one 110v outlet. What is the reasoning??? The only thing I can think of is that if the 220v device faults it could send 220 through the 110v neutral. Thoughts ???

JL..................

http://i911.photobucket.com/albums/ac317/JoeLee09/Electrical%20Schematic%20220%20Volt/Image001.jpg

lbhsbz
02-28-2011, 03:10 PM
Why not just come off of your existing 110V outlets and add a couple 110V outlets to that circuit, then run your new 220V circuit as you were planning on.

John Stevenson
02-28-2011, 03:24 PM
You sure your lot got a man on the moon ? :rolleyes:

I mean you struggle to get 3 wires across America :D

Mcgyver
02-28-2011, 03:32 PM
won't work - you also need neutral to get your 110 - ie one L + neutral = 110. You'd need to do 4 wires (or three + metal conduit) assuming its legal to go that route. I'd just go in steel conduit one run for 220 and one 110, its nice keeping everything separate and the materials aren't that expensive


Now....... there is a couple ways to do this. the first way is just to take one leg of the 220 line and ground and you have your 110. Done with 3 wires. Although not recommended and not to code we have all seen it done before. Technically there should be a neutral wire there for the 110v outlet.

my initial response was based on the diagram...but reading this, wow, run the other way from that idea. While a closed circuit, there's a much potential and current flow in the neutral line as there is L1 or L2....if this is routed through ground, doesn't that make every box, machine, motor frame, stick of conduit live while its a closed circuit? I don't think I've ever seen that done and it sounds like a death trap...maybe i',m having a brain cramp and missing something but that just seems crazy to me

Black_Moons
02-28-2011, 03:33 PM
Its not allowed and not a good idea for a few reasons:

Plug too much into the 120v outlet, and the other circuit that uses that neutral, And you could overload the neutral with the combined current. (If you don't use opposing phases)

And what if someone turns that circuits breaker off, And then starts mucking with the circuit, disconnects the neutral only to find.. ZAP, its still live via some other circuits load!

Or maybe at some point someone switchs the phases at the breaker box. Yaknow, Just changes the breaker/disconnect and reconnects em however is convienant.

Sharing neutrals with unrelated circuits stoped when we gave up knob and tube. For good reason.

kennyd4110
02-28-2011, 03:34 PM
You will need nuetral conductor from the main panel to the disconnect box for the 120v to work properly, you cannot use the ground wire per code...your electricain freind is 100% correct.

Carld
02-28-2011, 03:58 PM
Use the existing wires to pull a red and black #8 and a white #8 and a green wire through the existing conduit. Now put a breaker box where you would put the disconnect and work your circuits out of the breaker box. You will have to change the breaker in the main box to a 220 double breaker.

If the conduit is to small use a surface mount conduit of the needed size.

JoeLee
02-28-2011, 06:06 PM
won't work - you also need neutral to get your 110 - ie one L + neutral = 110. You'd need to do 4 wires (or three + metal conduit) assuming its legal to go that route. I'd just go in steel conduit one run for 220 and one 110, its nice keeping everything separate and the materials aren't that expensive



my initial response was based on the diagram...but reading this, wow, run the other way from that idea. While a closed circuit, there's a much potential and current flow in the neutral line as there is L1 or L2....if this is routed through ground, doesn't that make every box, machine, motor frame, stick of conduit live while its a closed circuit? I don't think I've ever seen that done and it sounds like a death trap...maybe i',m having a brain cramp and missing something but that just seems crazy to me

My diagram is for the most part correct. The first way I described taking a 110v was to grab one of the lines and use the ground...... that is not a real safe way to do it altough I've seen it done all over the place. A 220 device only needs the two lines to run, the ground is just there for safety reasons. useing that ground as a nuetral could cause the conduit to become hot if the 220 device faults. I on't do it that way myself. My question in wondering was if I could just grab the nuetral from the existing 110 box rather than run a nuetral all the way back to the main box.

JL.............................

lbhsbz
02-28-2011, 06:16 PM
I believe the NEC allows you to share neutrals...BUT, you have to have a means to kill power to all circuits sharing that neutral simultaniously...like by using a 2 pole breaker or a tie bar between all the single pole breakers using that neutral..., such that you can't shut off only one and have a "live" neutral on the other. As far as sizing goes, the neutral doesn't carry as much current as the hot, so 2 circuits shouldn't be a problem...if it was, the NEC wouldn't allow it.

Mcgyver
02-28-2011, 06:17 PM
A 220 device only needs the two lines to run, the ground is just there for safety reasons. useing that ground as a nuetral could cause the conduit to become hot if the 220 device faults..

I don't think that's the case; if you go L1 to ground to create a 110 circuit, both are hot when the 110 circuit is closed - you would not need a 220 fault to make it hot. It'll work as in the power will flow, but everything connected to ground will be hot when the circuit is closed.

using neutral from the other 110 line is safer, although by no means legal or good - as the other guys have pointed out you could have current from more than one breaker going through the neutral potentially in excess of it rated current plus someone in the future could turn off the breaker only to get electrocuted as neutral in the circuit he thought i turned off was live from the second circuit using it. Not worth it imo.

JoeLee
02-28-2011, 06:25 PM
I don't think that's the case; if you go L1 to ground to create a 110 circuit, both are hot when the 110 circuit is closed - you would not need a 220 fault to make it hot. It'll work as in the power will flow, but everything connected to ground will be hot when the circuit is closed.

using neutral from the other 110 line is safer, although by no means legal or good - as the other guys have pointed out you could have current from more than one breaker going through the neutral potentially in excess of it rated current plus someone in the future could turn off the breaker only to get electrocuted as neutral in the circuit he thought i turned off was live from the second circuit using it. Not worth it imo.

Your correct, when the 110v device is on the return or nuetral / ground becomes hot because it's now the return path. I wonder if it's OK to share grounds?? between the 220 and the 110 ?? or should the ground also be brought from the main panel along with the nuetral??

JL....................

tdmidget
02-28-2011, 06:44 PM
Seems to be some confusion here. Neutral and Ground are not the same and not interchangeable. This has killed/injured many. The NEC, like many rule books is at least partially written in blood.
It seems to me , with your limited understanding, an electrician would be a good investment.

Rich Carlstedt
02-28-2011, 07:09 PM
Isolating the 220 and the 110 from each other is good.
People have done what you suggest, but if you ever have a fire and the insurance company finds out.........

The correct way to do this is to use a stepdown transformer.
Go to a scrap dealer. any old industrial machine will have one ( control Transformer)and then you wire it for 220 input and have a isolated 110 output..much safer

Rich

garagemark
02-28-2011, 08:02 PM
What is it with some people? Why gamble with your life or your home or shop? Is it because you're cheap? Is it just too hard to do maybe? This is by every means cutting too many corners. Will you get bit? Maybe. Maybe not.

If you want to know how to install this circuitry correctly, you should ask for help. I would be happy to assist (assuming you are in the US). But if you are trying to get away with something (which your drawing on almost every level indicates), you will get no reinforcement from me; and I hope very little from anyone else.

Am I giving you hell? You betcha. I work with low, medium and high voltage power in an industrial setting every day. That's my career. I absolutely know, and have seen what can happen when people cut corners or simply make a mistake. I even lost a friend to electrical dumb ass many years ago.

Do it right. Live.

JoeLee
02-28-2011, 08:29 PM
What is it with some people? Why gamble with your life or your home or shop? Is it because you're cheap? Is it just too hard to do maybe? This is by every means cutting too many corners. Will you get bit? Maybe. Maybe not.

If you want to know how to install this circuitry correctly, you should ask for help. I would be happy to assist (assuming you are in the US). But if you are trying to get away with something (which your drawing on almost every level indicates), you will get no reinforcement from me; and I hope very little from anyone else.

Am I giving you hell? You betcha. I work with low, medium and high voltage power in an industrial setting every day. That's my career. I absolutely know, and have seen what can happen when people cut corners or simply make a mistake. I even lost a friend to electrical dumb ass many years ago.

Do it right. Live.

For the most part my drawing is correct. There is no code violation in the USA running 220 in the same conduit as 110 as long as there is no low voltage wires in that same conduit such as phone or tv. One of the methods I stated ( using L1 and Gnd) was not something I had planned on using, I only stated that I have seen it many times and know it's an incorrect shortcut.
I was just inquiring as to why I couldn't take a nuetral from a nearby line in the same conduit as opposed to having to run a dedicated one from the main panel. I'm not trying to do this becaus I'm cheap, It's just because the conduit is there. I wired my whole shop 25 years ago both 110 and 220 and had it all inspected. Asking for help here was what I was doing but I think there is some confusion between my drawing and my question.

JL.............................

lbhsbz
02-28-2011, 08:52 PM
There's nothing wrong with what you want to do IF you can get a tie bar to tie together all three breakers (your 2 220V legs and the 110V that you're borrowing the neutral from).

Black_Moons
02-28-2011, 09:07 PM
Just run 3/ conductor cable in the conduit for 2 hots + neutral + ground, insted of 2/ conductor.
(The ground is only counted in wire conductor count if its insulated)

lakeside53
02-28-2011, 09:19 PM
You cannot legally run run 3 wire+G CABLE (like Romex) in conduit.... The cable jacket is already a conduit.


And.. the NEC 2008 introduces the need to use a tie bar or common trip breaker for the 2 live legs of a three wire circuit, even if you just derive 2 120 volt circuits from it.

Forrest Addy
02-28-2011, 09:22 PM
What's being offered as electrical advise in many posts of this thread makes me REAL nervous. All that's been discussed so far is covered by electrical codes both national and whatever you have for local.

You can run but you can't hide. If you ever want your electrical mods to pass inspection you better comply with code requirements. They are the minimum acceptable and in some cases could be improved.

I'm not current in the latest electrical code so I wouldn't dare offer electrical advise without qualification and not being informed at all of the electical code of the OP's jurisdiction, I'm not offering it period.

I will suggest to JoeLee in the strongest terms possible to spend a hundred bucks and hire a local licensed electrician to go over the job with you, have him make specific reccomendations, materials, wiring, devises, where and how, plan the runs, and so on. Armed with this information you can rough in the installation install the boxes etc yourself. Have the electrican check it out and only then complete the installation. There's damn good reason for limiting conduit fill, grounding rules, Romex in conduit, etc.

In the long run it will be cheaper and it will pass code. Then if there is a fire for some reason a fire marshall won't spot somethe electrical that's substandard and write up his report accordingly - resulting in your insurance claim being denied.

And by the way, I feel confident in this: there is a difference between a ground conductor and a neutral. A neutral conductor is a load current carrying conductor and is grounded only at the service entrance and nowhere else in the distribution. A ground conductor carrys no load current. It's for fault current only and connects the metallic parts of electrically powered equipment to ground potential to protect personnel from contact with energized surfaces should an electrical fault occur. The fault current is conducted to ground thus tripping the circuit over-current protection.

Forrest Addy
02-28-2011, 10:07 PM
Double post

J Tiers
02-28-2011, 11:51 PM
OK you KNOW why you are NOT gonna use ground as a neutral.... right?

Now, you are also NOT gonna "borrow" a neutral from somewhere else.

1) Depending on what you have chosen which line it is, you will either double, or cancel the neutral current.... From same line, you double, which is putting 40A protection on a 20A wire..... OK, versteh? Got it?

2) If the "other" neutral is in another conduit, bad move...... the ground impedance just went up, so fault current may not pop the breaker as fast. And you add potential conduit heating to the other problems, since current is now going unbalanced through both conduits.

3) if the "other" neutral is in the SAME conduit, see #1, and you may fall under the 3 wire dual 120V rules, which as noted seem to have changed as of 2008.

Assuming the conduit "fill" is not out of line, just pull the wires you need to keep the circuits separate and proper. Wire is cheap, compared to the alternative.

I've seen the hack jobs..... 14ga aluminum wire tied to hot and neutral of one side on a 40A breaker..... I liked that one.....not.... Or twist the ceiling light wire and box wire together, wrap with scotch tape and call it good....

Don' BE like that.

Don Young
03-01-2011, 12:00 AM
It seems to me that your question basically boils down to whether you can use the same neutral for two circuits and the answer is NO. At one time the NEC allowed this as long as the two circuits were fed from opposite legs of a 120/240 panel but I think that has been changed.

Another consideration is that it is not permissible to run the hot and neutral for a circuit in different conduits or cables.

You can, however, run a 240V 4 wire feeder to a small sub-panel and then split off a 240V and a 120V circuit which might be your easiest solution. As someone else mentioned, if your 120V load is small then a transformer is feasible.

JoeLee
03-01-2011, 12:31 AM
There is on other way I can do this........ I can use a 5 pole plug and 5 wire cord and keep the 220 and the 110 seperate with out any sharing and without having to run a separate nuetral from the box, with the exception of the ground which would be shared. I'll have to check to see if that is OK.

JL...............................

Carld
03-01-2011, 12:53 AM
Joe, the simplest and best way is to run a sub panel as I suggested in post #7. From there you can run the circuits as needed. It's safe and legal.

J Tiers
03-01-2011, 01:29 AM
If you JUST want 120V at the lathe, for some type 'convenience outlet", for controls, lamp, TP grinder, etc, a transformer is best. probably cheaper than a monster plug.

I believe I got confused* with two different circuits, the one to the lathe alone, vs the one shown going off to left for mill.

You can, from electrical surplus joints, get a "4-way" transformer of a suitable power level. A 1500 watt might cost $50 used. Smaller cheaper. That's if no contactors etc are involved needing 120V power. if they are, then a "control" transformer is best, they have the oomph to drive AC contactors.

*
My excuse is that I have to scroll back and forth to read the post since the pic is oversized.

Mcgyver
03-01-2011, 10:41 AM
What's being offered as electrical advise in many posts of this thread makes me REAL nervous.

that's not very helpful if you don't say what posts/advice. I mean if you're ambiguous about what you thinks is incorrect it just perpetuate the problem or worse, casts doubt over all the posts that were good advice :confused:

lakeside53
03-01-2011, 12:06 PM
It seems to me that your question basically boils down to whether you can use the same neutral for two circuits and the answer is NO. At one time the NEC allowed this as long as the two circuits were fed from opposite legs of a 120/240 panel but I think that has been changed.

.

You can. The typical residential 12/3+G isn't going away, although it may be inconvenient as you can't just disconnect one circuit; you need a common trip or breaker tie for both circuits. I'm building out a small data center that has 42 three phase L21 plugs above the equipment racks from which we were deriving 3 separate 120 volt circuits (each plug). The equipment uses redundant power supplies fed from different circuits. The newly adopted 2008 code requires all three to have a common trip "means of disconnections", so overload one leg, and you loose all three legs.

BTW, any local jurisdiction can override the NEC code.. but most choose not to.

JoeLee
03-01-2011, 04:36 PM
I went over my diagram with an electrician friend today and he said just run a nuetral from the main box and I'll be OK. Sharing the nuetral from the exsisting 110 line will work but not wise since it's on a nother circuit. Sharing the ground is OK. So I'm all set. Thanks for all the input.

JL.................

Forrest Addy
03-01-2011, 05:36 PM
McGuyver, no it's not helpful but it is diplomatic not to parade other people's bad advise and dissect it to their disadvantage. Some will take it in stride and go on to examine their own posts and draw lessons. Others may simply take offense if not erupt in fury.

I will say this. Declare your qualifications when it comes to electrical advice. If you only know what your brother in law told you over a beer then you'll have to admit that falls short of a 4 year apprenticeship and passing a state license exam.

I've wokred with and around electricity since I was a boy playing with a battery and buzzer moving on to considerable electrical experience. Does that make me an electricain? No. While there may be a few things I could tell a good industrial electrician I fall way short of being qualifed for general electrical work. BUT, I do know where and how to look things up and extract knowledge I need to procede. I also have a couple of local electricians I can consult - part of my network.

The last place to look for electrical information is in a home machinist forum. Lots of nice people willing to help but few possessing the detailed knowledge necessary. Upgrades of your home shop electrical system not only has to pass inspection but has to be suitable, economical, and practical.

Rosco-P
03-01-2011, 05:48 PM
Sharing the nuetral from the exsisting 110 line will work but not wise since it's on a nother circuit. Sharing the ground is OK. So I'm all set.
JL.................
Sharing a ground is okay if the ground is appropriately sized. Sharing a neutral between two (nearly) equally loaded 110VAC circuits, protected by a 2 pole breaker with a common trip is okay. I can't imagine how sharing a single neutral between several circuits would be allowed.

Mcgyver
03-01-2011, 06:14 PM
McGuyver, no it's not helpful but it is diplomatic not to parade other people's bad advise and dissect it to their disadvantage. Some will take it in stride and go on to examine their own posts and draw lessons. Others may simply take offense if not erupt in fury.


is it? diplomatic? not so much to ones who gave good advice, and for those who'll take offense at being wrong or erupt, well anyone with that big a need-to-be-right should just be ignored. Ambiguous criticism might do more harm than good...everything else you had to say was right on I thought, it was just the 'many posts' part that I wondered about.

You of all people have the credible and eloquence to nicely point where there's an error without it being percieved as personal attack. Risk of a bruised ego is the lesser of two evils compared to ignorance or even danger, right?

free world, or at least forum, it's just I'd rather hear what you're thinking straight up so thats what i tried to encourage

Forrest Addy
03-01-2011, 07:23 PM
is it? diplomatic? not so much to ones who gave good advice, and for those who'll take offense at being wrong or erupt, well anyone with that big a need-to-be-right should just be ignored. Ambiguous criticism might do more harm than good...everything else you had to say was right on I thought, it was just the 'many posts' part that I wondered about.

You of all people have the credible and eloquence to nicely point where there's an error without it being percieved as personal attack. Risk of a bruised ego is the lesser of two evils compared to ignorance or even danger, right?

free world, or at least forum, it's just I'd rather hear what you're thinking straight up so thats what i tried to encourage


Ah, but I do point out errors when I feel it necessary but privately. And yes I try to do so politely and constructively. I seem to recall a couple of messages went your way over time.

Mcgyver
03-01-2011, 10:04 PM
Ah, but I do point out errors when I feel it necessary but privately. And yes I try to do so politely and constructively. I seem to recall a couple of messages went your way over time.

hmmmm....have I ever been wrong :D

obviously j/j, just ask my bride....but I don't remember a PM ever....??

J Tiers
03-02-2011, 12:05 AM
The last place to look for electrical information is in a home machinist forum. Lots of nice people willing to help but few possessing the detailed knowledge necessary.

And some of us have to know our way around the code for business, and if in doubt, will go to the shelf for the book and look it up.

lest anyone should be deceived, some of the worst not-to-code wiring I have seen has been done by electricians. They aren't always right. Neither are the engineering types.

But both are usually "righter" than Bubba.

garagemark
03-02-2011, 07:07 PM
We electricians are some of the worst when it comes to wiring around the house "by the book". We [think we] know what we can get away with. I have done some dumb stuff, but the older I get, the more of it I am rectifying.

Giving electrical advice over the Internet is in a forum like this is not really sound- even if it is correct advice. The NEC is but one document regarding installations. Many local codes are even more stringent than the Federal laws. What I can do here in my West Virginia city, you cannot do in New York City.

My best advice is going to be for you (or anyone else that has a project they are unsure of) to contact, in the least, your electrical supplier. I don't mean the big box stores. I mean a 'do nothing else but provide electrical supplies' supplier. Best place to go if you cannot afford a licenced electrician. There are some pretty sharp cookies at most of those places.

JoeLee
03-02-2011, 07:38 PM
Well if it's safe to do in West Va. then why wouldn't it be safe in NYC???

JL...................

darryl
03-02-2011, 08:43 PM
There are some pretty smart cookies around, but unless you're savvy enough to decode what advice you're getting (here or anywhere else) you stand to make some errors if you blindly follow the advice. So far on this thread the advice has been good- in general I can sum it up by saying that you do need a return wire if you're going to use 110 from a 220 feed. Using the ground as the return will work, but totally erases the safety that the ground wire is there to provide. Jumping over to another neutral wire will work also, but I know that if I asked my electrician friend, he would say NO NO NO- you would essentially be allowing a neutral wire in an electrical box to become hot, even though you may have killed power to that box with the breaker. The code is all about safety, not about whether 'it would work if I wired it this way'. The neutral wire you use should be in the same wire bundle that you get the two phases from for 220. That way if you open the breaker for that feed, there's nothing else wired in that could possibly feed a live voltage to any of the wires in that box.

I've just alluded to something else here- there should not be more than one live wire coming in to any one electrical box. That would mean more than one breaker would have to be tripped to shut off power into that box- functionally it could be fine, but it's a safety issue again.

If anyone has the argument 'I wired it so I know what's what here'- sooner or later you will forget anyway, and when anyone else has need to open up the electrical system for some reason ( a new owner perhaps) they won't know of any 'offbeat' wiring practice that has been put in place, so they might expect that if they flipped the breaker, that box is safe to work in. Your wiring should not become a future danger to someone else.