240v -upgrade from 3 wire(10-50) to 4 wire

[tonycastec]

I have used "search' but can't find a discussion of this issue so would appreciate some direction or link to a useful thread. This must be becoming a more common issue? My 1980's garage was professionally wired for 240v and has '3 wire' 10-50 receptacles. The wiring is overkill 6awg THHN in steel conduit within the walls (behind drywall).The previous owner traded the work with a commercial electrician who obviously had some oversize left-overs he wanted to use up!
Some new equipment I am installing uses 14-50 and 14-30 plugs. I would like to upgrade the 10-50 and 10-30 receptacles to the corresponding NEMA 14-** without major rewiring. It is European equipment so the neutral+ground bonding is not feasible.
The existing 10-50 receptacles are wired red,black,green(yes ,green not bare) in steel conduit. I was (naively?) thinking I could just tape the 8 awg thhn green with white in each receptacle. In the service entrance box in the garage I would move and tape white the corresponding green to the neutral bus.I would use the conduit as the ground with a jumper from the 14-50 receptacle to the receptacle box. I have no 240v equipment with the old bonded neutral+ground strap .
The upgraded wiring won't be inspected and I am not interested in an NEC rules debate-just what will work safely with 14-50 receptacles.I am also adding a sub-panel for a 5hp compressor so if it is absolutely essential,I could pull an extra (6? white) conductor through the existing conduit.But it is behind drywall and who knows what issues there may be trying to fish an extra conductor through the conduit.
Thanks for any constructive contributions.

 

[Stuart in MN]

What equipment are you installing? In general, air compressors, welders, and most other 240vac machine tools don't require a neutral - just two hots and a ground. A neutral is needed for devices that also require 120vac, like a kitchen stove.

 

[tonycastec]

Thanks for raising this issue Stuart. You are correct -"240v doesn't need a separate neutral & a separate ground" is the old propaganda. Think about it... why does 120v get a separate neutral and ground but not 240v? That is why the old 3 wire 240v receptacles and plugs are obsolete -even for 240v water heaters that technically do not 'use' a neutral.Similar reasoning for 120v 2 wire receptacles.
The 4 wire 240v protocol(NEMA 14-**) is the current code for new installations/construction. Other countries that use 240v (like U.K.& colonies)have had separate ground and neutral since the 1960's . They even have a fuse in every plug too -and breakers for every circuit like we do. That may be the next money-maker for the electrical equipment manufacturers here -a fuse in every plug -kinda like a 'chicken in every pot'? Imagine the money they would make if we all had to change to fused plugs.

 

[Stuart in MN]

If you're running a neutral wire to a 240vac air compressor, where are you connecting it?

 

[Charles (in GA)]

If you're running a neutral wire to a 240vac air compressor, where are you connecting it?

Better than that, lets ask him to give us specific tools, devices, machines, that might be found in a home shop or even a light commercial shop, that require a neutral. Neither of my welders do, one is a fairly new Lincoln TIG/Stick unit that runs on virtually any voltage you can supply it with, my compressor doesn't need a neutral, my Challenger lift doesn't need a neutral, my drill press, when run on 240v doesn't need a neutral.................

Charles

 

[tonycastec]

The question "why do you need a neutral & a ground with 2 pole 120=240v systems is one best addressed by the NEC & NEMA. Why did the make all the 3 wire 240v receptacles obsolete if separating neutral and ground wasn't a good idea? Why go to all the trouble of the new 14-** system,if it is unnecessary?
Can anyone answer the original question ,please?
I have used "search' but can't find a discussion of this issue so would appreciate some direction or link to a useful thread. This must be becoming a more common issue? My 1980's garage was professionally wired for 240v and has '3 wire' 10-50 receptacles. The wiring is overkill 6awg THHN in steel conduit within the walls (behind drywall).The previous owner traded the work with a commercial electrician who obviously had some oversize left-overs he wanted to use up!
Some new equipment I am installing uses 14-50 and 14-30 plugs. I would like to upgrade the 10-50 and 10-30 receptacles to the corresponding NEMA 14-** without major rewiring. It is European equipment so the neutral+ground bonding is not feasible.
The existing 10-50 receptacles are wired red,black,green(yes ,green not bare) in steel conduit. I was (naively?) thinking I could just tape the 8 awg thhn green with white in each receptacle. In the service entrance box in the garage I would move and tape white the corresponding green to the neutral bus.I would use the conduit as the ground with a jumper from the 14-50 receptacle to the receptacle box. I have no 240v equipment with the old bonded neutral+ground strap .
The upgraded wiring won't be inspected and I am not interested in an NEC rules debate-just what will work safely with 14-50 receptacles.I am also adding a sub-panel for a 5hp compressor so if it is absolutely essential,I could pull an extra (6? white) conductor through the existing conduit.But it is behind drywall and who knows what issues there may be trying to fish an extra conductor through the conduit.
Thanks for any constructive contributions.

 

[Norcal]

The question "why do you need a neutral & a ground with 2 pole 120=240v systems is one best addressed by the NEC & NEMA. Why did the make all the 3 wire 240v receptacles obsolete if separating neutral and ground wasn't a good idea? Why go to all the trouble of the new 14-** system,if it is unnecessary?
Can anyone answer the original question ,please?
I have used "search' but can't find a discussion of this issue so would appreciate some direction or link to a useful thread. This must be becoming a more common issue? My 1980's garage was professionally wired for 240v and has '3 wire' 10-50 receptacles. The wiring is overkill 6awg THHN in steel conduit within the walls (behind drywall).The previous owner traded the work with a commercial electrician who obviously had some oversize left-overs he wanted to use up!
Some new equipment I am installing uses 14-50 and 14-30 plugs. I would like to upgrade the 10-50 and 10-30 receptacles to the corresponding NEMA 14-** without major rewiring. It is European equipment so the neutral+ground bonding is not feasible.
The existing 10-50 receptacles are wired red,black,green(yes ,green not bare) in steel conduit. I was (naively?) thinking I could just tape the 8 awg thhn green with white in each receptacle. In the service entrance box in the garage I would move and tape white the corresponding green to the neutral bus.I would use the conduit as the ground with a jumper from the 14-50 receptacle to the receptacle box. I have no 240v equipment with the old bonded neutral+ground strap .
The upgraded wiring won't be inspected and I am not interested in an NEC rules debate-just what will work safely with 14-50 receptacles.I am also adding a sub-panel for a 5hp compressor so if it is absolutely essential,I could pull an extra (6? white) conductor through the existing conduit.But it is behind drywall and who knows what issues there may be trying to fish an extra conductor through the conduit.
Thanks for any constructive contributions.

Not trying to be nasty, but your over your head & you need the services of a qualified C10 electrical contractor. A green conductor is not permitted to be re identified ever....

 

[Charles (in GA)]

Does your "European Equipment" even work on 60 hz power? and why do you need a neutral on it? If it uses ONLY 240v, then all you need is the two hots (and the ground of course) and it will work exactly as it did in Europe on the hot/neutral power used over there. I don't understand why it would have three current carrying wires plus the ground. I don't think single phase European equipment uses anything like that.

I don't think you understand, 240v does NOT use a neutral in the US. The neutral is provided when it is needed for "stuff" inside the basic equipment that is powered by 120v current.

Charles

 

[tonycastec]

Lets not get distracted.Let me gently nudge you back to the original question.
I asked a question and got oblique comments. So I referred the critics to NEC & tried to return to the question. If you think 14-** & 4 wire 240v is redundant- great ,speak to NEC, not me. I don't presume to second guess NEC. Their new standard is 4 wire, so I'll follow it.
I was just hoping for an answer to the opening question about upgrading wiring from 3 wire to 4. This tangential stuff just repels other potential contributors who might be inclined to volunteer an answer if the thread stuck to the original question.
If you don't have an answer -that is O.K- really it is quite alright. Please don't hijack a useful thread as a platform for a rant on a tangential issue -at least not until you have earned some cred by answering the original question.
So to restate the original question, can one upgrade a 3 wire system to 4 by using the conduit as the ground and the original ground/neutral as a dedicated neutral?

 

[KenC]

I'll take a stab at the question:

Yes, you can.

No, it doesn't met the code, if it's based on the NEC.

That's due to remarking a green wire which is specifically not allowed.

If it were me, I would invest in enough white wire to replace the green. Just tie it to the green and pull it in.

Some folks don't like using the conduit as ground, but I'm not one of them.

I do use compression fittings instead of set screw connections. I think they make a more solid connection that won't increase in resistance over time.

 

[buzz4041]

Yes if want to be in direct conflict with the code. Norcal already gave the answer in previous post. You keep quoting the NEC requirement yet you keep wanting to violate it to the extreme. Pull the required white conductor and be done with it.

 

[tonycastec]

Ken,
THANK YOU !
Hey someone answered the question !
I understand your reservations and the recommendation to just pull the new white conductor.My conduit is all fully threaded connectors(that I can see).
I thank for your contribution and hopefully it will help anyone else considering an upgrade from 3 to 4 wire.
One unusual category of potential users are those with electric cars that are rigging their own charging stations.

 

[KenC]

Now that I've tried to answer your specific question, let's discuss why you want to do this. It is my understanding that the code does not require 4 wire circuits to all 240 recepts, just those that happen to be intended for ovens, ranges, dryers etc. Those are the appliances that use 120v internally for some functions. Therefore they require a separate neutral to prevent current from flowing in the grounding conductor.

Welders, 240 motors and such have no such requirement.

 

[tonycastec]

Please re-read:
I specifically said I wanted to avoid pulling another conductor.
I specifically said I did not need to have it inspected and wasn't interested in an NEC rules debate.
Fortunately another forum member answered the question .My thanks to him and I hope others find ken's answer useful too.

 

[buzz4041]

Fortunately the help from this forum is to have people do it correct and not jury rig installations like you which may become a problem for someone else in the future. First word of my post was YES if you would like to RE-READ it.

 

[KenC]

Please reconsider why you are doing this instead of disregarding some pretty good questions.

I think most of us believe it is not required on all 249v recepts but is usage dependent.

Can you please specify the code section that you interpret as requiring the upgrade? It may help someone else.

 

[tonycastec]

Ken, Thanks for your response.
I did not say the upgrade was required by code(in old construction). All I said was new construction has 4 wire 240v and 3 wire is obsolete(for new) .
IMHO 14-** will become a standard in place of 10-50 -rather like 2 wire 120v upgraded to 3 wire years ago.
Eventually (if this is correct & perhaps I am wrong?) we'll all be making 3 to 4 wire adapters or changing old 10-50 receptacles to 14-50 for example.

 

[Charles (in GA)]

Please re-read:
I specifically said I wanted to avoid pulling another conductor.
I specifically said I did not need to have it inspected and wasn't interested in an NEC rules debate.
Fortunately another forum member answered the question .My thanks to him and I hope others find ken's answer useful too.

For some reason, you seem to be expecting someone here to tell you to go ahead and do it, despite the fact it is not code. That is not going to happen. You have already been told, Yes, it electrically can be made to work, beyond that, you figure it out, you already know the answer. You've already been told it isn't code, and none of the responsible people on this forum are going to tell you to do something that isn't code.

Charles

 

[Stuart in MN]

Ken, Thanks for your response.
I did not say the upgrade was required by code(in old construction). All I said was new construction has 4 wire 240v and 3 wire is obsolete(for new) .
IMHO 14-** will become a standard in place of 10-50 -rather like 2 wire 120v upgraded to 3 wire years ago.
Eventually (if this is correct & perhaps I am wrong?) we'll all be making 3 to 4 wire adapters or changing old 10-50 receptacles to 14-50 for example.

Copied from the other thread:

I think you're getting your NEMA connectors confused. NEMA 14 connectors took the place of the old NEMA 10 connectors, and are used for things like kitchen stoves or clothes dryers that have both 120 and 240vac requirements. NEMA 6 connectors are used for 240vac only devices like welders or air compressors, and are still in regular use. http://en.wikipedia.org/wiki/NEMA_connector

 

[sberry]

This is mental ************ at best, waste of time and energy. 4 wire is only needed for appliance with dual voltage, thats why you see it in new residential. Its that simple. This forum is a good ploace to learn but you are going to have to be willing to listen.

 

[tonycastec]

I found this and it may help:
As you likely know, the neutral is the primary return path for any single phase circuit while the ground is a safety return path in the event of a fault - to help eliminate the potential for shock from any metal casing in the event of an internal short.

At the main panel the service neutral and the outside ground rod (and any internal water pipe or supplemental ground for that matter) are all technically one and the same wire and point - but that is where it ends.

Once you leave the main panel on any grounded system this extra added ground wire now serves a totally new purpose and because it is now isolated from the neutral from that point on - it adds the extra degree of protection that the neutral cannot - it is picking up any "bleed" to metal on all your appliances (the frame of your light fixtures or dryer or stove, etc) and taking that back to the panel and hopefully tripping the circuit breaker monitoring that circuit in the process.

The neutral, having an internal connection inside that device can NOT do this. So this is the main purpose (and why it's required) for this isolated ground (isolated only in reference to the neutral) to provide that extra safety path back to the panel. In the event of a fault or short electricity has a quick way back to main ground. Without this ground path the user might encounter a shock touching the device if it has an internal fault or in the case of electronics - internal circuitry damage may occur.

Technically it is more or less redundant - the two wires have no difference in potential - as say, the hot black and neutral would - but the 2 wires now serve completely different purposes once they leave the main panel.

 

[tonycastec]

Charles,
Please re-read:
"you seem to be expecting someone here to tell you to go ahead"
Where did I ask for permission ?

 

[Aceman]

Thanks for any constructive contributions.

Here's constructive:

Taping a green wire white is hack. Period.

You have conduit, so repulling the correct colored wire in isn't rocket science. Tape the new wires onto the end of the old one and pull. That's all there is to it and now it's done right.

The time you've spent on here defending your position could've been spent doing it right. I bet you'd already be done by now.

 

[Stuart in MN]

I found this and it may help:
As you likely know, the neutral is the primary return path for any single phase circuit while the ground is a safety return path in the event of a fault - to help eliminate the potential for shock from any metal casing in the event of an internal short.

This is the case for a 120vac circuit, but not for a 240vac circuit - a neutral wire is not required or needed.

 

[tonycastec]

I am defending nothing.I simply asked(politely) and have tried to nudge the conversation back toward the question.
It is sad that some use a question as an opportunity to rant.It is interesting to observe that the rants often indicate no interest in the original question.
I am glad to have provided an opportunity for some to vent. More positively I am grateful for the constructive answers.
The issue of taping a green conductor white is interesting from the point of understanding the intent of that code rule. Most common conductor colors can by code re-designated with a different color of tape. I wonder what the problem with green taped white was? I am more interested in understanding the reason for code than just dogmatically following it -assuming no safety issue and no inspection.
The 14-30 receptacle would be a great upgrade for people who have washer/dryer in their garage ?

 

[PRH44]

Tonytcastec you have received excellent advise from a top notch group of poster with vast experience and knowledge. They are here to help you with any problems or questions you may have. They will go into any detail necessary to help. I would highly recommend you consider and respect their advice especially when it comes to a code compliant installation.
You have every right to do what you like. If you are determined to install 4 wire receptacles and circuits that’s fine. Please do so in a safe manner. You may want to sale the property someday and it may be inspected.
Electrical installations need to be code compliant for several reasons. The paramount reason is to protect human life. Be sure you know exactly what the neutral conductor is used for in your equipment if needed at all. I for one have concerns you may not fully understand. I would post your wiring diagrams here for review before you install or energize anything as we are here to help. Or employee a qualified electrician.

 

[tonycastec]

PRH44
Thanks for your thoughtful reply.
As far as safety is concerned,we established that nothing proposed was unsafe.
In my opening question I made it clear that I was interested in safety,not code.
It may be interesting to discuss(in another thread)the code issues raised.

As a hint to some who seem to have venting/ranting needs here is a gentle nudge toward a related subject for them to snap about :
Code says(?) you can not tape green conductors white -except if they are 4awg or larger diameter ? Why? Is this a compromise of cost vs.trivial safety or just an indication why it is better to understand regulations than just to blindly follow them -and attempt to browbeat other to follow too? Perhaps that is a Free Parking discussion on seeking enlightenment vs. dogma?
I bow out now with sincere thanks to those who made constructive comments on the original question. Thank you.

 

[sberry]

I am more interested in understanding the reason for code than just dogmatically following it -assuming no safety issue and no inspection.
The 14-30 receptacle would be a great upgrade for people who have washer/dryer in their garage ?

For a dryer yes an upgrade from 3 wire to 4 is a good thing but accomplishes nothing fir single voltage appliances, welders, air comps, etc, there is not going to be a future code to add a wire to these. 2 power wires and a green or bare ground. This is something they are not changing in codes, Its understandable, you think you know and understand something you don't if I am reading this right, good to see you asking.

I did not say the upgrade was required by code(in old construction). All I said was new construction has 4 wire 240v and 3 wire is obsolete(for new) .
IMHO 14-** will become a standard in place of 10-50 -rather like 2 wire 120v upgraded to 3 wire years ago

.
Yes, it is reqired for new,,, in some cases, (what, since 96) but it isnt going to become a standard where its not needed.

 

[tonycastec]

I found this and it may help:
As you likely know, the neutral is the primary return path for any single phase circuit while the ground is a safety return path in the event of a fault - to help eliminate the potential for shock from any metal casing in the event of an internal short.

At the main panel the service neutral and the outside ground rod (and any internal water pipe or supplemental ground for that matter) are all technically one and the same wire and point - but that is where it ends.

Once you leave the main panel on any grounded system this extra added ground wire now serves a totally new purpose and because it is now isolated from the neutral from that point on - it adds the extra degree of protection that the neutral cannot - it is picking up any "bleed" to metal on all your appliances (the frame of your light fixtures or dryer or stove, etc) and taking that back to the panel and hopefully tripping the circuit breaker monitoring that circuit in the process.

The neutral, having an internal connection inside that device can NOT do this. So this is the main purpose (and why it's required) for this isolated ground (isolated only in reference to the neutral) to provide that extra safety path back to the panel. In the event of a fault or short electricity has a quick way back to main ground. Without this ground path the user might encounter a shock touching the device if it has an internal fault or in the case of electronics - internal circuitry damage may occur.

Technically it is more or less redundant - the two wires have no difference in potential - as say, the hot black and neutral would - but the 2 wires now serve completely different purposes once they leave the main panel.

 

[Charles (in GA)]

I found this and it may help:
As you likely know, the neutral is the primary return path for any single phase circuit

I think everyone one of us in this discussion understands the purpose of a separate ground and neutral.

The statement above is correct for 120v current in the US, but is not true of 240v current. In US 240v single phase (aka "split phase"), there is no need for a neutral. The neutral is the center tap off the power company transformer secondary windings. 240v is tapped off the two ends of the transformer secondary windings (aka "line to line"), and alternating current technically does not have a "return path" as 60 times a second, current reverses direction, both are supply and both are return, depending on which side of the waveform we happen to be looking at for any given moment. Since in 240v we do not have a GROUNDED conductor (the neutral tap off the transformer), we have to protect both sides of the circuit with circuit breakers (thus the double pole circuit breaker). If we had a European type of 240v circuit, we would have a neutral, which is the grounded conductor, tapped off one end of the transformer, and the "hot" tapped off the other (there is no middle tap) and thus only one circuit breaker (single pole). However, the effect is the same, 240v of alternating current supplied to the appliance or device (save for the fact it is 50 hz, vs the US 60 hz) as that in the US.

At this point, I give up, either you understand this simple difference between 240v in the US (and Canada, and a few other places) and the 240v in Europe, or you don't..............

After re-reading this thread, I'm beginning to smell a troll.

Charles

 

[tonycastec]

Thanks for the explanation .I understand.

 

[Norcal]

You cannot re identify ANY green colored conductor, period. Any case of doing it is a code violation & a hack job where the one who did it has either no idea what they are doing or just does not care.

 

[tonycastec]

If the green conductor is 4awg or larger diameter .............?

 

[Charles (in GA)]

Code says(?) you can not tape green conductors white -except if they are 4awg or larger diameter ? Why? Is this a compromise of cost vs.trivial safety or just an indication why it is better to understand regulations than just to blindly follow them -and attempt to browbeat other to follow too?

250.119 Identification of Equipment Grounding Conductors.

.............................. Conductors with insulation or individual covering that is green, green with one or more yellow stripes, or otherwise identified as permitted by this section shall not be used for ungrounded or grounded circuit conductors.

Charles

 

[PT Doc]

I think everyone one of us in this discussion understands the purpose of a separate ground and neutral.

The statement above is correct for 120v current in the US, but is not true of 240v current. In US 240v single phase (aka "split phase"), there is no need for a neutral. The neutral is the center tap off the power company transformer secondary windings. 240v is tapped off the two ends of the transformer secondary windings (aka "line to line"), and alternating current technically does not have a "return path" as 60 times a second, current reverses direction, both are supply and both are return, depending on which side of the waveform we happen to be looking at for any given moment. Since in 240v we do not have a GROUNDED conductor (the neutral tap off the transformer), we have to protect both sides of the circuit with circuit breakers (thus the double pole circuit breaker). If we had a European type of 240v circuit, we would have a neutral, which is the grounded conductor, tapped off one end of the transformer, and the "hot" tapped off the other (there is no middle tap) and thus only one circuit breaker (single pole). However, the effect is the same, 240v of alternating current supplied to the appliance or device (save for the fact it is 50 hz, vs the US 60 hz) as that in the US.

At this point, I give up, either you understand this simple difference between 240v in the US (and Canada, and a few other places) and the 240v in Europe, or you don't..............

After re-reading this thread, I'm beginning to smell a troll.

Charles

Some just get it and some just don't and will repeatedly ask the same thing.

Did you say troll?

 

[tonycastec]

Charles
Thanks for the reference. I couldn't find the specifics but gladly take your word for it.
I got the 4awg reference from a source that my have been superseded :
NEC 200.6
Mike Bahr, James Stallcup - 2003 - Architecture
Thanks for the correction

 

[tonycastec]

Charles ,I found it and for others who may follow here is the source so they can read it-from another forum:
http://www.selfhelpforums.com/archive/index.php/t-9682.html
"The 2005 NEC seems quite clear on this...last sentence first paragraph of Art.250.119..."Conductors with insulation that is green, green with more than one yellow stripe or otherwise identifyed as permitted in this section shall not be used as grounded or ungrounded conductors."
Thanks Roger, that was it. In 2002, 250.119 didn't specifically say that. I wish I had an easy to use online copy of the 2005 code.
Roger
August 22nd, 2006, 03:27 PM
Yep, until 2005 it was an argument either way but we havent been able to remark a green insulated wire around here for as long as I can remember.
In fact I would have to agree that before 2005 you would have been just as right as wrong.

Seems I remember Wg as always advocating that you couldnt remark a green insulated wire as a current carrier. If I remember over the years he had several people on different forums as well as this one ask for clarification on this matter. He always said... no you werent allowed. I dont remember all the referenced codes he used but he had a very strong argument against being able to remark green insulated wires as hot or grounded conductor wires."
So the issue has changed over the years and several smarter people than me have been confused by it.
The 4awg issue probably isn't very useful to the typical Res.garage anyway.
Anyway thanks for all the help .The hostility of some towards those of us who really try to understand is a little distracting but I am still grateful for the help in leading me to the source .

 

[gc427]

What kind of European equipment are you attempting to install?

 

[tonycastec]

Here is another link to a (polite) discussion of this issue. Even among code experts it caused some disagreement .And I specifically excluded code compliance in my opening question. Anyway the following link may help others because it does quote code line by line with comments by smarter minds than mine:
http://www.diybanter.com/home-repair/208779-rewire-220v-110v-color-question-3.html

 

[Norcal]

............................................................................................................ .And I specifically excluded code compliance in my opening question.

...................................................................................................................................................................................................................


With that I think it's time to end this disscussion.