Running 240v for MIG welder

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Old 03-31-16, 08:59 PM
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Running 240v for MIG welder

I had 6awg wire with 50 amp breaker running from my house to my detached garage--about a 85 foot run to the subpanel in the garage. It was set up as 220v. There is also a separate 110v 12awg.

When I moved into the house, the 220v was split at the subpanel to make two more 110 lines in the garage. I just had no need for 220 service in there.

A number of years ago, I had some excavation done in my yard and the guy hit and broke the #6 wire which was buried. I replaced it with 8 wire. So, from breaker box to where it exits the house is #6 (about 30 ft), then buried from the house to the garage is #8 (about 40 feet), then where it enters the garage to the subpanel is again #6 (about 15 feet).

So, that breaker should be changed to a 40amp, I guess. I never changed it because I knew I would never pull that many amps. The biggest thing I run is a table saw along with flourescent lights.

But now, I would like to run a MIG welder in the garage. I would like to use a 220v with as many amps as possible.

So I figure I would wire as follows:

1) Change the 50amp breaker in the main panel to a 40amp to account for the #8 wire.

2) In the garage, I would take the two lines that were 220v that I split into 110s and I would splice them (or come out of the subpanel with them with #8) so that in addition to still being two 110s, they would also be a 220 again.

3) The 220 would go into another subpanel with a 30amp breaker.

4) From this new 30amp subpanel, I would run the welder.

This way I would be able to use a 30amp 220v welder. I guess I could use a 40amp in the subpanel but I figure because of the distance I should step it down a little.

Any thoughts?
 

Last edited by rmathome; 03-31-16 at 09:15 PM.
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Old 03-31-16, 09:24 PM
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First off you don't have 110 or 220. You have 120 and 240.
It was set up as 220v. There is also a separate 110v 12awg.
The 120 separate supply is a code violation and needs to be abandoned. You can only have one feed to a detached structure. That is your subpanel.
In the garage, I would take the two lines that were 220v that I split into 110s and I would splice them (or come out of the subpanel with them with a higher awg) so that in addition to still being two 110s, they would also be a 220 again.It was set up as 220v. There is also a separate 110v 12awg.
Hard to understand what you mean but certainly doesn't sound correct.

What you need to do is abandon what you have and run larger wire in conduit or direct burial cable to your garage. Direct bury quadruplex aluminum mobile home cable would probably be the cheapest choice. Probably 2-2-4-6 on a 100 amp breaker at the main panel. You will need at least a 12 space 100 amp main breaker panel for a subpanel at the garage. Most do not come with a ground bar so you will need to buy and add a ground bar. If that is the panel you already have and you have the required ground rod then all you need is the new cable and breaker.
 
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Old 03-31-16, 10:10 PM
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I'll try to explain better what I plan to do--which does not include abandoning what I have and running anything new.

Lets say I have three #8 wires (since part of the run is #8) running to a subpanel in the garage. The three wires are red, black, and white. In the house, the red and black are connected to a 50amp 240v breaker, white goes with all the other whites.

I will change that to a 40amp 240v breaker.

In the garage, in the subpanel, the white goes to the spot for the whites. The red and black suppl two legs for power. It is a fused subpanel similar to this:
https://www.nachi.org/forum/attachme...b-panel-i6.jpg

There is a 20 amp fuse on each leg (black/red)

Coming from each leg, currently is #12, that runs to various outlets and lights.

What I would do is leave the #12 coming from the subpanel. I would add to that #8 from each leg (and #8 from the white) and connect this to a 240v outlet. At first I was thinking about running this to a second subpanel, and then running the new outlet from there. But I dont think that would change anything.

So, the new setup would have the #8 coming from the subpanel in addition to the #12.

The #12 would do what it has always done--power lights and outlets. the #8 would power a 240v outlet.

So, essentially, after all this typing, I am only doing two things:
1) in the house, change the breaker from 50amp 240v to 40amp 240v
2) in the garage, run #8 from the subpanel to a 240v outlet
 
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Old 03-31-16, 11:20 PM
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You do NOT have a "sub-panel" in the garage. In fact, the term "sub-panel" does not even exist in the National Electrical Code (NEC). What you DO have is a fused safety switch. You CAN replace that switch with a circuit breaker panel.

A number of years ago, I had some excavation done in my yard and the guy hit and broke the #6 wire which was buried. I replaced it with 8 wire.
What kind of "wire" is used? Is it individual conductors in conduit or is it a type UF (Underground Feeder) cable? Please tell me that it is NOT individual conductors without conduit or (worst case) type NM cable. Are there any splices underground? If in conduit please specify what type of conduit.

You didn't mention it so I must assume that you did NOT run a fourth conductor for equipment grounding between the house and the garage, is there ANY metallic wiring or piping (cable TV, Internet, telephone, water or sewer service etc.) between the house and garage? Did you drive a proper grounding electrode (ground rod) and connect it to the white wire in the safety switch? If no "other metallic paths" exist then you MAY be grandfathered with this arrangement but it does not meet current NEC requirements. The ground rod is NOT optional.

Depending on the insulation on the #8 conductors AND the method used in the run (type UF cable or individual conductors in approved conduit) the wiring MAY allow for the use of the 50 ampere circuit breaker. If you used type UF cable then you definitely need to downsize to a 40 ampere CB.

Post back with the answers to these questions for further advice.
 
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Old 03-31-16, 11:21 PM
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The alleged subpanel (really a fused disconnect switch) isn't acceptable for what you want to do and the other 120 cable needs to be disconnected. You could replace the fused safety switch with a 100 amp subpanel and feed it with 40amps but it wouldn't meet code because you only have three wires. While that is grandfathered right now any changes mean you need to bring it up to current code. That means two hots, a neutral, and a ground (EGC). You will also need a ground rod (GEC) if you don't have one.

Furd types faster and covered it more thoroughly.

Edit: We really need to see what you really have at the garage. That image you posted may be giving everyone the wrong idea. http://www.doityourself.com/forum/li...rt-images.html
 

Last edited by ray2047; 04-01-16 at 01:19 AM.
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Old 03-31-16, 11:58 PM
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Ray, as I read it rmathome does not have a "separate 120 volt cable" but is deriving his 120 volts for lighting and receptacles from the 240 volt feeder under discussion.

Whether or not replacing the fused switch with a proper circuit breaker panel would trigger the requirement to bring the entire installation to current code is a judgment call and is up to the LOCAL inspector. The grounding electrode (and minimum #6 copper Grounding Electrode Conductor (GEC)) at the garage IS required and has always been required.
 
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Old 04-01-16, 12:34 AM
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Furd, he wrote in his first post:
There is also a separate 110v 12awg.
That was the one I was referring to.
 
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Old 04-01-16, 12:48 AM
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Yes, he did. He clarified that in his subsequent post stating it came off of the safety switch.

Coming from each leg, currently is #12, that runs to various outlets and lights.

What I would do is leave the #12 coming from the subpanel. I would add to that #8 from each leg (and #8 from the white) and connect this to a 240v outlet. At first I was thinking about running this to a second subpanel, and then running the new outlet from there. But I dont think that would change anything.

So, the new setup would have the #8 coming from the subpanel in addition to the #12.

The #12 would do what it has always done--power lights and outlets. the #8 would power a 240v outlet.
 
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Old 04-01-16, 01:10 AM
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He is going to have to clarify that. I read it as two #12s one from the switch and one from the house panel.

Also we need to get a real picture of what he has in the garage. That seems to be just a picture he grabbed from the internet because he wrote:
It is a fused subpanel similar to this:
Rmathome please post an actual picture of the garage panel. http://www.doityourself.com/forum/li...rt-images.html
 
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Old 04-01-16, 08:02 AM
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There IS a separate #12 run from house to garage. But for the purposes of this discussion, I think we can ignore it. Not to just blatantly ignore code, but because it doesnt run into the fuse box but to a separate junction box.

When I moved in, the #6 was already installed. I am guessing it has been there close to 50 years now. To be honest, I forget if I ran the #12 or if it also already existed and was also broken by the excavator and I replaced this too.

In any case, the #12 is individual wire in plastic conduit (red/black/white/ground), the splices are only where it leaves the house and where it enters the garage

As for the #6, I dont believe it is UF -- just cable with a real thick rubber sleeve. I have some leftover and cant see any kind of writing on it at all. But it was buried in the ground. No conduit.

The repair for the #6 was done with #8 UF. The splices are also where it leaves the house and enters the garage--no underground splices.

I dont see any ground to or from the fuse box.
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The thick black coming in at the top is the power. The other three are outgoing.
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This is some of the leftover that was in the garage when I moved in. Looking at how it is frayed, this may even be part of what the excavator broke.
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I can certainly abandon the #12. But I dont understand why I need to have a 100amp subpanel in the garage. Why cant it be a smaller one?
 
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Old 04-01-16, 08:22 AM
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The feeder almost looks like a flexible cord like SO. If so it was never for direct burial.
 
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Old 04-01-16, 08:23 AM
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Panels are rated for the maximum ampacity they can be fed with. You can feed them at a lower ampacity.
 
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Old 04-01-16, 11:34 AM
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That does not appear to be type S hard service cord but I can't identify what it is either. Perhaps one of the other electricians can identify it and tell you if it is acceptable for a direct burial underground feeder. It does appear to have four conductors.

There IS a separate #12 run from house to garage. But for the purposes of this discussion, I think we can ignore it. Not to just blatantly ignore code, but because it doesnt run into the fuse box but to a separate junction box.
Sorry, but no, we cannot ignore it. There are only five exceptions to the rule that allows only ONE source of power to a building and you don't qualify under any of the exceptions. This rule has been in place for decades.

The splices MAY be acceptable IF the boxes where they are made has the requisite volume for the size and number of conductors. If the splices are made in "conduit bodies" such as an LB or C there is a possibility that the volume of the enclosure is too small.

Being an outbuilding you definitely need at least one, and possibly two, eight foot long grounding rods. Many other specifications for the placement and connecting of the ground rod(s) we can discuss.

Within that fused switch you have two conductors under the load screw for the left-hand fuse, this is a definite violation. It also appears that the neutral bus has multiple conductors under each screw.

As PC mentioned, it is okay to install a circuit breaker (or fuse) panel with a higher amperage rating than the feeder. This is often done to have the requisite CB spaces for the required number of circuits. IF the panel has provisions for more than six circuits then a main CB is required to allow all power to be removed by throwing a single circuit breaker. Six circuits or less does not require a main CB but remember, it is the total number of separate circuits the panel can accommodate, NOT the total installed, that triggers the requirement for a main CB.
 
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Old 04-01-16, 01:47 PM
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Perhaps one of the other electricians can identify it and tell you if it is acceptable for a direct burial underground feeder
It is not buried anymore. It was. Until the excavator broke the cable. Then I replaced it with #8 UF, the splices being in a box before leaving the house and in a box when entering the garage.

There IS a separate #12 run from house to garage. But for the purposes of this discussion, I think we can ignore it. Not to just blatantly ignore code, but because it doesnt run into the fuse box but to a separate junction box.
Sorry, but no, we cannot ignore it. There are only five exceptions to the rule that allows only ONE source of power to a building and you don't qualify under any of the exceptions. This rule has been in place for decades.
I understand that but "for the purposes of this" discussion because it "doesnt run into the fuse box"

I am just trying to separate this as a different issue--to be dealt with separately (and quite easily)

The splices are with wire nuts most likely. If not that, then bug nuts due to the bulkiness, but most likely wire nuts for the correct size. I dont remember but can check if needed.

And the connections are definitely in boxes with plenty of space. 4inch boxes with extenders--I DESPISE working in tight little areas and trying to get my big fat fingers in spots that seemed to be designed for a small japanese woman hands.

So, if I change the breaker in the house to 40amp, and drop the separate #12 line, I should be able to switch the fusebox to a subpanel and add a grounding rod?
 
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Old 04-01-16, 03:53 PM
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I think I am beginning to visualize the entire project. Your first question, and you don't have to answer in print, is are you going to get a permit and inspection? I strongly suggest that you do so.

Then I replaced it with #8 UF...
Is that two-conductor with bare equipment ground, two-conductor with no equipment ground, three-conductor with equipment ground or three-conductor with no equipment ground?

The #6 cable appears to have a bare equipment grounding conductor. Does this bare conductor enter into the service (main) panel in the house and is it connected to the combination neutral/equipment ground bus? Assuming that you used UF cable with an equipment grounding conductor, did you connect the two equipment grounding conductors at both the house and the garage? If yes to these questions then you are in a good position. If you do not have a continuous (with splicing) equipment grounding conductor then your installation will not meet current codes but MAY be grandfathered as long as there are no other metallic paths between the house and garage as I previously described. This will be at the discretion of your local inspector.

At the garage you would connect the black and red wires to the main circuit breaker in the new panel OR, if the new panel cannot accept more than six circuits total, to the main lugs of the new panel. The white wire will connect to the neutral bus, which will be on plastic insulators AND the "bonding" screw (green) or strap that bonds the neutral to the enclosure must be removed. The bare equipment grounding conductor will connect to an equipment grounding bus bar which is almost always a separate purchase and field-installed into pre-drilled holes in the enclosure using supplied self tapping screws.

You need to drive the copper ground rod to full depth and connect it to the equipment grounding bus with #6 copper wire, preferably solid. This wire needs to be one continuous (no splices) length.

The separate supply between the house and garage will be terminated at the house and inside the garage it will be re-routed to the new panel. If this separate supply is a three-conductor cable (with additional bare equipment grounding conductor) it could be re-purposed as a three-way switch loop to allow a light to be switched from either the garage or the house. If it is only a two-conductor cable it will need to be physically disconnected at both the house and garage.

Yes, you need to change the house circuit breaker to a 40 ampere model.
 
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Old 04-01-16, 08:57 PM
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I guess the stranded silver wire on the #6 is the bare equipment ground?

That is unused at the house breaker box. It never enters the box. It was just pulled back and wrapped around the black rubber sheilding. So, I would have used #8 UF three-conductor with no equipment ground--just three wires (black, red, white) because the goal was to match the exising cable (aside from the gauge because I didnt care about matching #6 considering the price)

As for
is there ANY metallic wiring or piping (cable TV, Internet, telephone, water or sewer service etc.)
I dont really get the relevance--what is the concern about that? But I do have telephone wire run from the house to the garage. It is meant for underground and is 24 pair I believe. It may run alongside the #8 UF in the ground, I just dont remember. Although it does leave the house and enter the garage through different conduits.

I like having the phone in the garage, but if I had to abandon that, so be it.

So, I can follow the steps for grounding the subpanel that you have outlined or, without an equipment ground, am I out of code (unless grandfathered in)?

When you refer to bare equipment ground, does that just mean the bare copper as in a roll of cable that is "12-2 with ground"?

If each panel is grounded separately with grounding rods, why would a ground between the two be needed?
 
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Old 04-01-16, 09:43 PM
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I've had about two hours of sleep over the last 24 hours. I've been fighting with UPS and others during that time, none of which is any concern of yours. I tell you this because I'm getting a little short tempered now and some of that is from you constantly questioning me on code subjects.

A four-wire connection (hot, hot, neutral and equipment ground) has been standard for many years. Up until 2008 an alternate method eliminating the equipment ground was acceptable as long as no other metallic connections existed between the buildings. This prohibition on other metallic connections had been in place for many years as well. IF the three-wire connection between the house and the garage had been installed prior to your jurisdiction adopting the 2008 NEC you would most likely be grandfathered under the code enforced at the time of construction.

However, there are enough anomalies in your installation that I find it difficult to believe that any of it was installed under permit or was ever inspected. I will bend backwards trying to get you to a SAFE installation that was in compliance with the applicable code at the time of original construction but I will NOT help anyone to circumvent the intent (meaning safety) of the code whether it be a grandfathered system or to the latest code interpretation.

You are free to research the applicable sections of the NEC, it is available on-line in a read only format for free albeit you do need to register to do so. Or, you could buy the hard copy of the NEC, or better for a layman, the NEC Handbook which goes beyond the letter of the code and explains why the code wants things done in a specific manner. I do not recommend either book unless you are planning on taking up electrical work as your vocation. First is that the code is difficult to read without a strong background in electricity as well as an understanding of how legal documents are written. Secondly, the books are expensive, pricing starting at about $70 and rising quickly. Third, the code is revised every three years meaning the books go out of date to a greater or lesser degree pretty fast.

What I DO recommend is a small paperback book titled Wiring Simplified. This book has a price of about ten dollars, is usually available from the big box mega-mart homecenter or corner hardware store. It is found in the electrical aisles rather than the books and magazines section of the store. Wiring Simplified has been in continuous print for more than fifty years, revised every three years to incorporate the changes made in the NEC. It is specifically written for the lay person and explains in simple language the meaning and reasoning behind the code provisions. It will be the best ten dollars you could spend on this project.

Grounding is another complex issue. Entire volumes have been written on this subject and it is, in my opinion, one of the least understood subjects in the electrical field. Even many journeymen electricians as well as electrical engineers stumble badly when it comes to this subject. I don't make any claims to fully understanding it myself beyond knowing what is required by code.

Buy the book and read it cover-to-cover. Don't think for a minute that just because an electrical installation "works" it is safe or even semi-okay. Be safe, not sorry and never forget that electricity is an equal opportunity killer. It doesn't care in the least who you are, your marital situation, how many people depend upon you or anything else. If you don't respect electricity it will kill you dead. Over my life (65 years and counting) I have worked with and around voltages from 1-1/2 to 26,000 and I'm still alive because I respect electricity and don't take chances. Neither should anyone else.
 
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Old 04-01-16, 09:55 PM
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I'm getting a little short tempered now and some of that is from you constantly questioning me on code subjects
WTF?

If you don't want to answer the questions, then don't.
 
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Old 04-01-16, 10:20 PM
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If you want help be polite and remember we will only help you do it in a safe and code compliant way. We need the details of how it is now to help you correct any code violation as you proceed with the work.
 
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Old 04-01-16, 10:50 PM
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I have simply started a thread, asked questions, and provided answers as best I can to the followup questions of other members--with no sarcasm, criticism, antagonism, etc.

And Furd is getting shorttempered because of my questions? Not sure that lack of politeness is an issue on my part.

In fact, my last post (before my response to the shorttempering) was a long one full of answers to previous questions.

No?
 
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Old 04-02-16, 12:02 AM
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I guess the stranded silver wire on the #6 is the bare equipment ground?
Yes. Is there also a white, black and red wire?
That is unused at the house breaker box. It never enters the box. It was just pulled back and wrapped around the black rubber sheilding.
It needs to be connected on both ends.
So, I would have used #8 UF three-conductor with no equipment ground--just three wires (black, red, white) because the goal was to match the exising cable
It needs to be 8-3 with ground and the ground needs to be connected.

Under previous code you didn't need a ground if there were no other metallic path ways. Since you have a phone line that means even under previous code you needed a ground.

Does the UF cable you ran have white, black, red, and bare wire. If so we can use it.

Does the SE cable at the house have three insulated wires plus the stranded ground wire? If so it can be used.

If your answer is yes to both of the last two questions we can proceed with how to install your new subpanel.

Other Q&A:
When you refer to bare equipment ground, does that just mean the bare copper as in a roll of cable that is "12-2 with ground"?
Yes as to UF cable. For the SE cable from the house it is the stranded bare wire you mentioned.
If each panel is grounded separately with grounding rods, why would a ground between the two be needed?
The ground wire in the cable is to provide a low resistance path to trip the breaker if a hot shorts to the metal case of a piece of equipment. The ground rods are to minimize atmospheric charges. Earth resistance varies and can be too great to reliably handle short circuits so a ground rod isn't a substitute for the ground wire.

If I missed some of your questions just ask.
 
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Old 04-02-16, 07:28 AM
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The UF that I ran does not have a ground. Just black, red, and white, to attach to the used black, red, white of the SE cable.

So, I am guessing there is no way to ground this to code unless I run new ground (which of course needs to travel under a patio at this point)

So, old code did not require a ground. Does this mean that old code was less safe? I guess so (which is why it was updated?)
 
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Old 04-02-16, 07:44 AM
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Where did you find UF cable without a ground,?

Part of the issue is you were being told the safe and code compliant way this needed to be done and we were getting the feeling that you didn't care about the rules and doing this correctly.it is not that a person did not want to help, but the freely donate the expertise and have it ignored doesn't make many happy.
 
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Old 04-02-16, 09:31 AM
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Bottom line based on the facts you have told us the only way to do what you want to do is go from scratch. There is no way what you have can be made to work in a safe and code compliant manner. We will be happy to help you run a new feed to your garage.
 
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Old 04-03-16, 10:35 AM
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ok. the intent was not to give that impression. so, I apologize for any poor "tone"

All advice is appreciated.

It looks like my UF DOES have a ground. But I need to check better (everything is tough to get at)

If it has a ground, I am assuming I can connect the grounds, and a grounding rod, drop the #12 and the phone, change the breaker to 40amp and install a subpanel-- correct?

I will add more info when I get a chance to open all boxes.

But, again, all advice IS much appreciated.
 
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Old 04-03-16, 12:13 PM
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A separate question on this issue.

If there are multiple cables in a box, can/should all bare copper grounds be joined? Even if they are from different gauges?
 
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Old 04-03-16, 12:37 PM
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If there are multiple cables in a box, can/should all bare copper grounds be joined? Even if they are from different gauges?
Yes, even if they are from different circuits. Also if the box is metal they must be pigtailed to the box.

Neutrals on the other hand if from different circuits must not be combined.
 
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Old 04-03-16, 01:04 PM
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If you are able to run a continuous equipment grounding conductor (splices okay) from the service panel to the garage panel you will not need to remove the telephone wiring. The "no other metallic paths" rule only applies if there is no equipment ground from the service panel.
 
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Old 04-03-16, 01:24 PM
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Neutrals on the other hand if from different circuits must not be combined.
I thought that if they were from the same phase, they could be combined?

If you are able to run a continuous equipment grounding conductor (splices okay) from the service panel to the garage panel you will not need to remove the telephone wiring. The "no other metallic paths" rule only applies if there is no equipment ground from the service panel.
Okay, two questions here:
1) how can it be continuous, with splices? What would non-continuous be?
2)I thought that I MUST have an equipment ground (based on previous conversation here). I can get the ground in, so I will. But if I couldn't, I thought I was out of luck. Would i have just been able to remove the other metallic path?
 
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Old 04-03-16, 02:27 PM
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Okay, two questions here:
1) how can it be continuous, with splices? What would non-continuous be?
2)I thought that I MUST have an equipment ground (based on previous conversation here). I can get the ground in, so I will. But if I couldn't, I thought I was out of luck. Would i have just been able to remove the other metallic path?
Confusing? You are absolutely correct!

When I wrote continuous I meant that you cannot connect the equipment grounding conductor to the service panel and the new panel in the garage while not having a "ground" conductor in the UF that you have buried. Perhaps it would have been better if I had stated "continuity" from one end to the other.

Prior to the code revision of 2008 it was acceptable, but not preferred, to not have an equipment grounding conductor between the service panel and the outbuilding as long as there was no other metallic path between the two buildings. I don't know what triggered the code-making panel into revisiting this issue but they decided that the hazards were greater than previously determined and they removed the provision of allowing the less-preferred option. That means that from the date that your local jurisdiction adopted into law the 2008 NEC it has been unlawful to have a three-wire (no equipment grounding conductor) feeder to an outbuilding. Under the basic provisions of the NEC existing installations that met the code requirements at the time of their installation are still acceptable provided they are kept in the same configuration. Limited maintenance IS acceptable to maintain the original but any major changes will trigger the requirement to bring the installation to current code.

Now here is where it gets even more confusing. Assuming that originally the garage had ONLY the 12-2 cable from the house to the garage for a light and receptacle when the second cable (the #6) was installed it was contrary to the code article allowing only ONE feeder to an outbuilding. Even if the #6 cable came first the addition of the second cable was in violation and should have been caught by the inspector, assuming a permit and inspection was done. Regardless of which cable came first, the addition of the telephone cable also made the installation non-compliant. I KNOW that these provisions concerning multiple sources as well as other metallic paths go back at least 35 years but I couldn't say exactly when they took effect.

So this is the way I see it. IF you are able to connect the existing equipment grounding conductors so that you have continuity on that EGC from the service panel to the proposed circuit breaker panel, AND install a proper grounding electrode (ground rod) at the garage and properly connect it to an equipment grounding bus in the new panel, along with the provisions of no more than six possible circuits I previously mentioned as well as the 40 ampere CB in the service panel plus elimination of the 12-2 feeder cable then yes, you would be in compliance with current code and not have to remove the telephone wiring.
 
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Old 04-03-16, 02:53 PM
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I thought that if they [neutrals] were from the same phase, they could be combined?
No. Never have as far as I know. There are safety issues with that. If say breaker 1 was turned off and its neutral was combined with circuit 2's neutral then circuit 2's neutral could still have current on it. Touch the neutral of circuit 1 while grounded you could be an alternate return path for any 120v loads on circuit 2.
 

Last edited by ray2047; 04-03-16 at 04:55 PM.
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Old 04-03-16, 06:15 PM
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If the SE cable at the house is three conductor plus ground it can be reused. Even if you have to replace it it shouldn't cost that much.

The ground wire (your EGC) to the garage does not have to be in the cable sheath of the UF cable to the garage. You can use single conductor URD direct burial cable to bring a ground to the shed.
I dont understand why I need to have a 100amp subpanel in the garage.
It is to provide enough circuits for all your needs. Smallest panel is 60 amps bu the larges will only have six spaces.
 
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Old 04-03-16, 08:02 PM
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SE cable cannot be buried.
 
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Old 04-03-16, 08:40 PM
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PCBoss, if I understand him the SE cable only runs through the house to the outside where there is a junction box for the UF cable.
 
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Old 04-03-16, 09:07 PM
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If the SE cable at the house is three conductor plus ground it can be reused. Even if you have to replace it it shouldn't cost that much.
I am confused. By "reused" you mean it can stay in place? It already is spliced when it leaves the house, and again when it enters the garage.

The ground wire (your EGC) to the garage does not have to be in the cable sheath of the UF cable to the garage. You can use single conductor URD direct burial cable to bring a ground to the shed.
Would I be able to use the existing #12, that needs to be abandoned, as the ground? The gauge might be a bit small, but there would be three wires (black, white, ground - all #12 in conduit).

Although I believe I can splice the ground on the UF to the ground on the SE anyway. It will be a pain, though, but possible.

It is to provide enough circuits for all your needs. Smallest panel is 60 amps bu the larges will only have six spaces.
I really only need 4 spaces. Two for the 240, 1 for lights, 1 for outlets. And would still have 2 free.

I guess having even more is always better but not sure what I would use them for. What would be the common uses in a garage aside from lights, outlets, and a single piece of heavy equipment that would require more than six spaces?

And, I will be reducing the breaker that runs the subpanel to 40 amp due to the #8 UF. Can that be used for a 100 amp subpanel?
 
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Old 04-03-16, 10:27 PM
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I am confused. By "reused" you mean it can stay in place?
Yes.
It already is spliced when it leaves the house, and again when it enters the garage.
As long as it isn't buried you are okay.
Would I be able to use the existing #12, that needs to be abandoned, as the ground? The gauge might be a bit small, but there would be three wires (black, white, ground - all #12 in conduit).
Strictly speaking no. Wires that small can't be twined but since the ground doesn't carry current it would be a judgement call by the inspector. #10 THWN wire could be pulled through the conduit to provide a ground unless it is EMT*. If it is EMT it is probably rusted out and can't be used.
And, I will be reducing the breaker that runs the subpanel to 40 amp due to the #8 UF. Can that be used for a 100 amp subpanel?
Yes, it is done all the time. The installed 100 amp main breaker of a main breaker panel would be your disconnect switch. It doesn't matter it is 100 amps because it only serves as the code required disconnect switch. The 40 amp breaker at the house provides your protection.

You will have to buy and install a ground bar in most cases but they are cheap and you save money if you buy a main breaker breaker panel kit because it includes several branch circuit breakers and so many are sold the price is relatively cheap. While you might not need more than six breakers now a 100 amp panel is good future proofing.

The main question is how may amps do you need for the plasma welder.

*EMT is thin wall metal conduit which is too thin to thread. There is also IMC and RMC both of which are thick enough to be threaded. If either of those were used the conduit itself could probably be considered an adequate ground assuming it was continuous. (EMT is also considered an adequate ground but long buried EMT is probably to rusted out to be a viable ground.)
 

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Old 04-04-16, 09:32 AM
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The conduit is PVC, so I could pull #10 through. But, as long as my UF has a ground (it does), and I can splice it in to meet the SE ground, then I should be ok.

It will call for a couple of more splices since I think the pieces I am working with will be too short--the grounds from the UF I ran and the and from the SE probably wont reach each other if, since unused originally, may not have been left long enough. So I may need to cut the SE cable a few inches back, add a new box in, just to get length to work with. I'm assuming multiple splices are not an issue.

Now, a couple of final questions. Some for this job, some just out of curiosity.

1)
The SE is #6. The UF is #8. I guess I should have used #6 for the repair but didnt care, at the time, about my amps.

The #12 is in conduit. But since I will be removing this, I will have an empty conduit which, you mentioned I could pull a ground through. Is there any benefit to pulling #6 through and keeping my breaker at 50 amp?

2)
What is the purpose of the fused switch I currently have. Since it has fuses, I assumed it was a sub-panel. If it is just a switch, why would it need fuses?

3)
What is the reasoning behind not allowing more than one cable to a separate structure? As long as they are properly installed, how could there be a safety issue?
 
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Old 04-04-16, 12:19 PM
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The conduit is PVC, so I could pull #10 through. But, as long as my UF has a ground (it does), and I can splice it in to meet the SE ground, then I should be ok.
You wrote the UF has no ground. I missed your correction in a later post, sorry.
So I may need to cut the SE cable a few inches back, add a new box in, just to get length to work with. I'm assuming multiple splices are not an issue.
That will work.
The #12 is in conduit. But since I will be removing this, I will have an empty conduit which, you mentioned I could pull a ground through. Is there any benefit to pulling #6 through and keeping my breaker at 50 amp?
Depends on how many amps you need for the welder.
What is the purpose of the fused switch I currently have. Since it has fuses, I assumed it was a sub-panel. If it is just a switch, why would it need fuses?
Sometimes a device is fed with more amps then is required so the fused disconnect is there to protect it. Another example, most residential A/C condensers have built in circuit overload protection so an unfused disconnect is used. Some commercial A/C condensers do not have built in overload protection so a fused disconnect is required. I have also seen them in very old structures used as a main panel back when some houses had 30 amp 120 volt only service. (In general a disconnect is required for safety if a device is not within sight of the breaker box.)
What is the reasoning behind not allowing more than one cable to a separate structure? As long as they are properly installed, how could there be a safety issue?
Safety probably. The NEC doesn't explains just sets the recommended rules. Maybe one of the pros have an explanation.
 

Last edited by ray2047; 04-04-16 at 12:39 PM.
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Old 04-04-16, 12:49 PM
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I'm not sure how many amps I will need for the welder yet, as I am watching craigslist for one to buy.

However, I am only looking at 240v ones, which is what prompted this thread. From the models I have seen, they seem to give a range from 20 (min) to 50 (max)

So, naturally, I would want to set up with a 50 amp if I get a chance.

So, lets say I had one that was 50amp max. If I re-ran #6, and kept the 50amp breaker in the house. I would then, also, put a 50amp breaker on the subpanel (along with a couple of 20s for lights/outlets) I wouldnt be using the welder with anything other than a couple of flouresecent lights so, I would not likely trip the 50.

But, is that a legit setup? To have a subpanel powered by a 50amp, and have a 50 amp as one of the breakers in the subpanel. Or 40 in the main, and 40 in the subpanel? Can a breaker in the subpanel equal the breaker powering the subpanel.
 
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Old 04-04-16, 12:53 PM
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Welders aren't a continuous load and breakers can run 20 minutes or more at their rated max before tripping. Also consider if you use THWN wire it is rated for 60 amps so you could change the breaker to 60 amps.
 
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