# 220v Wiring



## dddddmorgan (Apr 24, 2015)

I'm sure this topic has been discussed ad nauseum but I'm wondering what are your recommendations based on experience for 220v wiring, three or four wire?

I'm remodeling the garage and I'm going to put boxes and pull wiring into the attic for the electrician and I will have two 220v outlets and I'm wondering if I need to go to the expense of four wire or not?

I don't think this will have any bearing on the plug end of any cord I will use will it?

And yes I've searched L.J. and I've had many of my questions answered but these specific ones I'm still wondering.

Thanks


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## jacksdvds (Jun 13, 2015)

Here is my layman's thought on this subject. IF there is only one operator and one 220 v. circuit being used at any one time what good would the extra wire do? The same philosophy is used for 115 v. circuits. If you are talking about a dedicated A/C circuit that is different. Ask your self, "How many starting loads at the same time could occur?".


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## splintergroup (Jan 20, 2015)

The four wire will allow for tools with built in task lights (110v).

You will need to change the plugs in your tools to match the receptacles.


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## dddddmorgan (Apr 24, 2015)

Sounds like I can run the two wire.

I just wasn't sure since I want to get a welder and switch my saw to 220v if I needed the extra wire.


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## MadMark (Jun 3, 2014)

Use:
Two wire *with* ground.

NEMA-6 connectors.

M


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## wapakfred (Jul 29, 2011)

Mark nailed it: 2 wire with ground. If they are 30 amp circuits, then use 10-2, for 20 amp circuits 12-2 (both with ground). The only time you need the 3 wire with ground is if there are 120V devices wired into the tool, something I've not seen. It's common on household appliances like dryers and ovens to have need of a 120V circuit (hence the 3 wire WG), but generally not on tools. The plugs/receptacles do need to match the service.


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## Carloz (Oct 12, 2016)

The cost of material is negligible compared to the expenses you need to go later if you need that fourth wire.
Some appliances and tools do require 220v and 110 v. Then I heard somewhere but did not try to find id in NEC and building codes that all *new *220 wiring requires 4 wires.


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## dddddmorgan (Apr 24, 2015)

Ya, there won't be anything fancy, just a table saw and a welder, perhaps in the future a compressor.

10/2 it is!


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## TripH (Feb 26, 2016)

Couple of considerations:

Length of run: As runs get longer, up-gauging is recommended and becomes code over extended distances - there are on-line NEC tables for reference… Most of my ruins are under 50ft and I run 10/2 up to 5HP - not required by code. 10/20 is an up-gauge in my application… As you approach 100ft runs, code-based up-gauging becomes required.

Cost: In some cases, 4-wire is cheaper than 3-wire (mfg volume). I priced-out 250ft spool of #6/2 and #6/3 and the 4-wire was substantially cheaper. I don't believe 4-wire is code for residential applications in North America and I don't believe it is being considered for adoption (but my NEC is a few years old, so YMMV), but it may be more cost effective.

Cost: Purchasing larger spools (say 250ft) can drop cost/ft dramatically. It's best to run all the same gauge to save on larger spool purchases.

Safety: Obviously check the plates on the various machines for Amp requirements. I personally recommend up-gauging every branch. I don't know what welder you have, but 10/2 would just squeak by for my setup. Same for my compressor. I run #6 for both.

Old Iron: If you ever intend to look seriously at old iron, run 4-wire (3-phase)...

Run all 220v the same gauge: You never know when you might reorg the shop, so run all the branches with the same gauge and same receptacles. I learned this the hard way-ran all 10/2, but matched the receptacles to the load - so I had a mix of 20a, 30a and disconnects… Then I went to reorg the shop and had a real electric task on my hands…

Think ahead: If you ever intend to do a substantial home renovation (or go to sell your home), the inspector may want to poke around (mine did when he noticed the sub-panel breaker in the main panel). To get his ticket, I had to change my shop receptacles to twist lock (NEMA L5 and L6). Now this was WAY out of scope, and I could have fought it - but I needed his ticket and not a hassle… So I said, "Yes Sir" and spent the $250 for new plugs/receptacles… The point is, when you run your branches, at least follow code to avoid any future problems.

DC: Shop DC is considered constant load, so must be on it's own dedicated branch-same inspector as above… Thank you very much…

Conduit: If your local application requires conduit (check - don't guess) - a lot of garage installs require it, then pull individual conductors (big cost savings). Some parts of the US are notorious for specifying requirements beyond NEC (ex. Chicago).

Good luck…


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## cathode (May 18, 2014)

Just being pedantic here, but 220v does not exist in north america. You have 240V or 208V line-line, 120v line-neutral.

It's possible that your utility service is off, but the spec allows for only a minor variation.

230V line-neutral is common in europe, however.


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## TripH (Feb 26, 2016)

Yea, yea… It's a 120v/240v/60h setup now, but the 220v tag is the historical (and colloquial) reference to the original 110v setup. Around WWII (early '50s?), the 110 setup drifted to the 120 setup-about saving copper, and therefore $$. The requirement was an allowable voltage range (110 - 130?) and 120v was in the range-- and cheaper to run.

Those with pre-war homes (count me in) may still have a few 110v outlets (which are un-polarized and, if old enough, without ground). Note to those with pre-war homes-ever wonder why you can't plug-in your new vacuum cleaner in that old socket at the back of the closet?

I'm not sure over what time-span the 110->120 switch was rolled-out, but I bet it was into the '70s. I'm not even sure if utilities today are required to deliver 120v, just somewhere between 110v and 120v.

BTW: I remember helping my dad with DIY electric and our panel was 110v/leg.

But if you say 220v to someone today in NA, everyone knows you're talking 240v/60h.

And to your point, we should now say 120/240.

Suppose your terminology depends what the voltage was when you helped your dad with DIY…


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## Carloz (Oct 12, 2016)

> Just being pedantic here, but 220v does not exist in north america. You have 240V or 208V line-line, 120v line-neutral.
> 
> It s possible that your utility service is off, but the spec allows for only a minor variation.
> 
> ...


There is no 230V in Europe. All networks supply 220V. UK is 240V.
230V is just a fake voltage that is between EU and UK so the electric goods could be designed to something that works in both EU and UK. In reality it is either 220V or 240V.


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## TheFridge (May 1, 2014)

So you're saying Santa Claus isn't real…


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## TripH (Feb 26, 2016)

I wonder if the local utility agreed to run 3phase to Santa's shop? Or maybe he generates his own from burning reindeer poop. Who knows? BTW: is the North Pole 50hz or 60hz?-I bet Mrs. Claus runs a pretty tight ship-- 60hz.

Boy are we off topic… Sorry.

Agreed, just run 10/2…


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## dddddmorgan (Apr 24, 2015)

Did some measuring when I got home.

The two 240 outlets will be within 2' of each other and only 39' run at the longest.

I will make the two outlets the same. I will only use one at a time but my line of thinking is that I will not want to have to switch machines back and forth.

I have a 19' x 20' garage so the chances of "old iron" are nil so I'm not going to worry about 3 phase.

I stopped by the big orange toy store on the way home and I might see if I can get some #6 wire, I have a couple of contacts there that could keep an eye out for a deal.

Thanks for the input.


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## MrUnix (May 18, 2012)

> I have a 19' x 20' garage so the chances of "old iron" are nil so I'm not going to worry about 3 phase.
> - dddddmorgan


You shouldn't worry about it even if you do get a three phase machine. The cost to wire your house up with three phase power would be significant, if it were even possible. If you do get a three phase machine (which are much more robust and efficient), just figure on another couple hundred bucks for a VFD and run it off your existing single phase 240V house supply voltage.

And while running 4 wires for three phase isn't really a valid reason, the others mentioned above are - like being able to pull 120V off the outlet sometime in the future, or even re-purposing the wiring sometime down the road to provide multiple 120V outlets instead of a single 240V one. And as also mentioned, it can be cheaper depending on where you get your wire.

Cheers,
Brad


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## wapakfred (Jul 29, 2011)

I'm getting a little blurry eyed here, but when did you decide to go #6 (if that's what has happened)? Way overkill for your application but more importantly, handling #6 wire is a royal PITA compared to #10. Just a thought.


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## rwe2156 (May 7, 2014)

Electric stuff gets crazy around here!!

So my biggest question is, if you're hiring an electrician why are you asking advice from a forum? You see what you get, right? 

Regardless, I'm sure the electrician will tell you 12/2 romex w/ 20A breaker will handle up to 3HP at FLA.

You would only need #10 if you're supplying a big like a 5HP compressor or some such beast (in which case you do dedicated circuits anyway).

My arc welder is wired #6/40A which would cover about any buzz box. It all depends on how big the welder is. If you don't have one yet, I would wait til you get it and then run a circuit. You may decide to to get a wire welder which don't take as much juice.

Check with your electrician.


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## TripH (Feb 26, 2016)

In the vast majority of cases, 10g is sufficient up to 5HP. Since your runs are short, you really don't need to go beyond 10g. I recommend 10g even if you have 3HP tools - because folks tend to 'upgrade' over time - and then there's that Craigslist purchase that just happens to come with a 5HP motor. Or you may get into shop-sawn veneer and want a fair-sized bandsaw. Point is, run 10g to future-proof your investment-it'll cost you maybe $25 incremental and will pay for itself with that first 5hp tool.

6g is overkill for all but industrial woodworking kit and, as mentioned above, a bitch to work with. In my shop, the welder and compressor are 6g tools (these are 85ft runs)... The wide-belt sander, thickness planer and surface planer are 8g 4-wire runs (3-phase). All of these loads are direct wired (per code) and the larger loads have motor disconnects (also per code). The Euro-kit all have built-in disconnects (which is handy).

Note: NEC has specific requirements for larger loads (I believe current NEC has requirement changes at 40a and 60a). While 99% of woodworkers can ignore these requirements, you may hit them with a welder or compressor. I'm not sure what's in the 2017 NEC, but you may require a direct-wired connect and/or a motor disconnect for these loads (as in my setup). Ask your electrician. And yes, these are a minor pain in the ass to implement, but if you ever need an inspection, it's best not to have obvious non-compliant wiring. As mentioned above, select your welder before pulling wire.

While not applicable to your situation, I'll touch on 3-phase to clarify my previous post. You don't necessarily need 3-phase run to your shop by the utility - as mentioned above, it's cost prohibitive, and may not be available in your area (my case). You can get shop 3-phase with a rotary phase converter (my situation) or get a point-of-use VFD. With centralized rotary phase conversion, you would run 4-wire from the 3-phase distribution panel. With point of use, you could run 3-wire to the VFD.

In any case, price-out spools of both 4-wire and 3-wire - sometimes 4-wire is cheaper by the spool. If you use an electrician, he/she can get the wire more cheaply than you can… Since you are in a garage, your municipal code may require conduit (ask your electrician). If so, it would be cheaper to pull individual conductors.

As mentioned above, ask your electrician for input. He/she is familiar with local municipal enforcement practice. If your town is like mine, they sometimes require above/beyond NEC, so a local electrician can easily pay for himself in avoiding rework.

Good luck.


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## WhyMe (Feb 15, 2014)

> In the vast majority of cases, 10g is sufficient up to 5HP. Since your runs are short, you really don't need to go beyond 10g.
> - TripH


Per the NEC, #10 is only valid for 5HP motor loads if hardwired and is THHN in conduit. #8 will be required if using NM-b(Romex) for the circuit. Also motor loads over 3HP need to be hardwired because standard NEMA plugs and outlets have HP ratings up to 3HP.


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## TripH (Feb 26, 2016)

From memory, the NEC table value (125% spec) on 5HP is 28a. So you can run a 30a branch without a requirement for direct wiring or separate disconnect (NEC-422?). Again, it's been at least five years since I looked at the NEC, but I believe this is covered under NEC-430 (motors). I believe THHN comes-in at the 90C table entry, which I don't think comes into play in this case.

Note: Our township is really conservative, and I passed with all my 5HP stuff on 10/2 Romex, receptacle connect without separate disconnect. Obviously, the stuff over 5HP is all direct wired w/disconnect. The only hang-up during the inspection was that all the receptacle-connect gear had to switch to twist lock. Maybe that was a compromise against hard-wired, but YMMV.

If I'm reading that wrong, please let me know what section covers the hard-wiring of 5HP motors.


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## WhyMe (Feb 15, 2014)

NEC table for 5hp is 28A but that doesn't include the 125℅ adjustment which will make it 35A. You can't use 90 deg rating because that is for derating purposes only.


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## coxhaus (Dec 14, 2015)

My welders all use 50 amp plugs. My 250 amp MIG requires an 8 gauge ground so I used 6 gauge wire. 8 gauge wire that I looked at only had a 10 gauge ground wire so I went with 6 gauge wire


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## squazo (Nov 23, 2013)

you absolutely need to use a piece of romex with 4 this will be called X/3 the x being whatever gauge you chose. you are going to hook up two hots one neutral and one ground. yes it is possible to use two hot and one ground/neutral but for the 33% cost savings is it worth it. To save something like 20 cents a foot is it worth it?


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## WhyMe (Feb 15, 2014)

You absolutely do not need 4 wires for a 240V circuit. Do you plan on hooking up a stove or dryer that will also require 120V? It's a code violation to use a common ground/neutral in a new three wire circuit.


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## TripH (Feb 26, 2016)

>you absolutely need to use a piece of romex with 4

Sorry, but that's just wrong...

You need 4-wire for a sub-panel (sometimes), 3-phase, single phase 240 and a 120, plus one or two other specific applications. You don't need 4-wire for a bog-standard 240v piece of woodworking kit... But it may be cheaper to pull 4-wire...

>NEC table for 5hp is 28A but that doesn't include the 125℅ adjustment which will make it 35A. You can't use 90 deg rating because that is for derating purposes only.

I agree with the 90C-not applicable. I'll have to find my NEC and check the tables. So the 125% isn't baked in? Live and learn… However, I can't believe I would have passed inspection if all my 5HP kit required 40a branches and I ran 10/2. Further, 40a requires hard-wiring /wo disconnect (if memory serves). Of course, with the exception of the DC, these are not 'continuous duty' loads. Perhaps the inspector let me slide with twist lock and the non-continuous load (intermittent is like 65% or 85%-never remember)? It was certainly within his discretion, but I can't see passing if my setup was non-compliant… Further confusion is that my DC is also 10/2 Romex and he made me end-run it because it's continuous load, not switch to 8g. Not that it I'll change my setup, but you've got me interested. I'll call the town compliance dept and ask… Now I've got to source a burn-phone


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## WhyMe (Feb 15, 2014)

I can speak for my location that some inspectors just do not know the nuances of the NEC when it comes to wiring motor loads in a residential use application. Technically a true 5HP motor as listed on the motor data plate should only be hardwired unless using pin & sleeve plugs. As I said before, standard NEMA plugs even the locking type are only rated up to 3HP and are not appropriate as a disconnect means for more than 3HP because of possible arcing. Hardwired motor loads need a disconnect if further than 50ft from panel or out of sight of panel.


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## TripH (Feb 26, 2016)

You just mentioned some stuff that I was noodling on…

First of all, I want to apologize to the OP for getting into the weeds…

While 5HP tools are not the norm for hobby woodworkers, they are far from un-common. Lots of folks out there have 20" planers, 18" bandsaws and DC units - all with 5HP.

In case folks are feeling a bit lost… Let me clarify the last few posts…

The NEC provides guidance for wiring-up kit based on application (AC Unit, Table Saw, Welders, Water Heater, Stove, etc), load (20a, 30a, 40a, etc), environment (garage, kitchen, basement, outbuilding, etc) and a few other things. Unfortunately, the 800page+ NEC is not a beacon of clarity. The various sections covering kit wiring can be contradictory, unclear or mute on certain specifics leading to a level of interpretation by the installer and inspector. This is one reason to hire a local electrician - he/she will have experience as to how the local inspector navigates/interprets the NEC.

What we are discussing is the requirement for 5HP workshop kit. There are several sections of the NEC that come into play, depending on interpretation. One section deals with general wiring requirements (load, conductors, insulation, environment), one with disconnect requirements, one with 'appliances' that have integral motors, one specific to motors and some subsections that deal with the application (continuous, intermittent, and a few other specific cases).

To add to the confusion, one section implies that motor plate values should be used as guidance, and another that basically tells you to ignore what's on the plate and use table values (that's a bit oversimplified, because you need some stuff from the plate to do the math). To further complicate things, HP has become a bit of a marketing spec. Just because a MFG markets a unit as 5HP (sounds powerful, doesn't it), it may not actually be 5HP (read as most likely). If one has an Asian-sourced unit, then it's likely specked in kw and more likely to be something like 3.0, 3.25 or 3.5 kw - all under 5HP. I haven't purchased new kit in years, so I don't know what Baldor, Leeson, etc are doing… To make a long story short, it behooves one to look at the plate. A further complication is the owner's manuals - they tend to over-spec the wiring. The manual for my PM 5HP bandsaw specified a 60a breaker, go figure?

So, we're discussing how to apply specific sections of the NEC to 5HP woodworking kit and weather it should be considered 30a or a 40a load. This is of interest because there are specific wiring requirements once you break the 30a threshold. I've got all my 5HP kit on 30a Romex 10/2 branches with twist-lock receptacles. If it turns-out that my kit would be considered 40a, then I'd [theoretically] have a bunch of re-wiring to do… Since I've lived on 30a branches for years and have yet to pop a breaker, warm any insulation and have an inspection ticket, I'll be keeping my setup as is… But I'm a hobbyist… If I was a commercial entity, then I'd change-over.

One final complication is that an inspector doesn't have to exactly follow NEC if he/she has a good reason not to. In my case, the inspector passed my 10/2 Romex on 5HP kit, deemed my DC as a 'continuous load' (so I had to rewire it) and made me swap-out for twist-lock plugs/receptacles (a couple hundred bucks)...

Sorry, I should have been more clear, up to 30a are standard twist-lock and P&S out to 50a. Since they also twist to lock, I just bundled-them-in…

==>Hardwired motor loads need a disconnect if further than 50ft from panel or out of sight of panel.
Thought that kicked-in over a certain load. From memory, 70/422 is really vague in places.

Important note for all those who follow, YMMV… And hire a local electrician…


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## dddddmorgan (Apr 24, 2015)

TripH I don't mind "getting off in the weeds" as my questions were answered.

I enjoy a good technical discussion. Just ask my kids, I put them to sleep all the time ;-)


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## dddddmorgan (Apr 24, 2015)

And after thinking about it and all your mention of twist lock connections, can anyone tell me what kind of receptacle I would encounter if I bought a 240v welder or compressor? Is there a standard or do they come like stoves and dryers where you put your own kit on it?


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## dddddmorgan (Apr 24, 2015)

Sorry I've missed a couple of posts. The reason I'm asking here is I'm going to be the one putting the outlets in the garage and pulling wire over to the panel but the wife is balking at me hooking them up and will have the nephew (certified) do the final hook up. Since this will only cost me beer I'm not too hurt.

Mostly I just didn't want to get him over there and have him say "geez that's puny wire!" or something like that.


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## TripH (Feb 26, 2016)

All my larger kit (including welder and compressor) was supplied sans plug and wire. Just a terminal box for installer hookup.

In my case, I added 6ft of whip (SEOOW?) and terminated in a 50a 'California Connectors' (which do turn-lock in place). IF memory serves, they are non-NEMA, but widely accepted. I also seem to remember that the receptacles and plugs were about $150/pair. This too passed inspection.

==>Mostly I just didn't want to get him over there and have him say "geez that's puny wire!" or something like that.

Give him a call and discuss your requirements. He will be able to purchase the correct stuff the first time around and more cheaply then you can…


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## WhyMe (Feb 15, 2014)

> And after thinking about it and all your mention of twist lock connections, can anyone tell me what kind of receptacle I would encounter if I bought a 240v welder or compressor? Is there a standard or do they come like stoves and dryers where you put your own kit on it?
> 
> - dddddmorgan


The thing is welders and compressors are totally two different animals when it comes to wiring. Typically welders use a 6-50 plug. To complicate things because welders have duty cycles you can have wire smaller than normal for a certain breaker size such as a 50A breaker on 30A wire using a 6-50 plug but the circuit is dedicated for welder use only. It's safer to just make a general purpose circuit using #6 Cu on a 50A breaker with a 6-50 outlet.


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## MrUnix (May 18, 2012)

I just standardized on the 6-50 as that is what my Millermatic welder had on it. My only other 240V tool is the table saw, and I put a 6-50P on it as well. I also made a 40 foot extension cord with 6-50 plug and outlet. And yes, it is a 50A circuit.

Cheers,
Brad


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## Rob_s (Sep 12, 2016)

So if one were guarding against future plans, and planning on installing two 240V circuits/outlets in the shop, how many amps would be suggested? I have a 125 amp panel in the shop but I can't use all of that as it also has to feed the 120v lights and outlets, the pool pump, and two mini-splits in the attached apartment. Would two 30 amp circuits be sufficient for just about any woodworking and/or home-use welding equipment?


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## wapakfred (Jul 29, 2011)

Most likely, yes.


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## coxhaus (Dec 14, 2015)

> So if one were guarding against future plans, and planning on installing two 240V circuits/outlets in the shop, how many amps would be suggested? I have a 125 amp panel in the shop but I can t use all of that as it also has to feed the 120v lights and outlets, the pool pump, and two mini-splits in the attached apartment. Would two 30 amp circuits be sufficient for just about any woodworking and/or home-use welding equipment?
> 
> - Rob_s


You should be covered for wood working with 30 amps. The standard for welding is a 50 amp plug. The little cracker box stick welders all have 50 amp plugs. Like the Lincoln tombstone welders which make an excellent home stick welder.

Just because you have a 125 amp panel does not mean the breakers need to add up to 125 amps. You can easily run a 50 amp breaker on a 125 amp panel. I run a 50 welder plug on a 60 amp panel. I just don't use anything else when I run my welder except for lights and a few small things.


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## TheFridge (May 1, 2014)

I haven't run across a piece of equipment that needed a neutral yet. That's what control transformers are for. It's just as easy to get 208-240v coils and indicator lights. If you run 3c w ground you're wasting money.


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## Rob_s (Sep 12, 2016)

> So if one were guarding against future plans, and planning on installing two 240V circuits/outlets in the shop, how many amps would be suggested? I have a 125 amp panel in the shop but I can t use all of that as it also has to feed the 120v lights and outlets, the pool pump, and two mini-splits in the attached apartment. Would two 30 amp circuits be sufficient for just about any woodworking and/or home-use welding equipment?
> 
> - Rob_s
> 
> ...


i've actually been having a hard time finding the amperage requirements for the Lincolns. They're so busy bragging about their amperage output.

That's a good point, and i'm mostly aware of it, but I do need to make sure that the pool equipment and the mini splits don't conflict with anything. Those have to get priority since I can't be turning them on and off all the time. so my thought is that 
[welder outlet] + [min-splits] + [pool equipment] + [lights] <125>ve been eyeing
http://store.lincolnelectric.com/webapp/wcs/stores/servlet/en/leesite/equipment/mig-welders/power-mig-reg%3B-210mp-multi-process-welder-p-k3963-1


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## TripH (Feb 26, 2016)

I have always pulled 10/2 for woodworking tools and 6g for a welder. I used 6g for my compressor because I had enough left on the spool.

However, I'm still noodling the 5HP issues raised above.

If future-proofing includes 5HP tools, then I'd consult a local electrician or your township compliance department before pulling anything. It would be such a pain to pull 10/2 to a 5HP saw only to replace it with 8g.

As a side note: I did find my NEC and there's a caveat to the 28a table value * 125% that drives a 40a/8g branch. NEC-430.6-exception3 states that if the motor has a plate that lists HP and amps, you ignore the HP and table values in favor of the plate's FLC to size branch conductors. I assume the 125% still applies. I'll have to check each plate, but I'm reasonably sure most of my 5HP motors are sub-5HP (marketing). So, I bet they squeak-by at just under 30a.


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## dddddmorgan (Apr 24, 2015)

Now my head hurts…

The only welder I have is the little H.F. 120v stick welder and it's great for what it is.

My goal would be to one day have a Lincoln "Tombstone."

Gonna call the Nephew and tell him there's a bottle of Bushmills sitting at my house waiting for him if he brings wire with him, that'll get the boy going!


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## wapakfred (Jul 29, 2011)

Well, the Lincoln tombstone I have is 50 amps, as was mentioned above….but I guess when you said "home use welding equipment" I was thinking of a unit like Rob linked above. Since it's convertible between 120V and 240V, I have to think it's requirement is 30 amps at 120V, and it probably runs off a 20 amp circuit on 240V.


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## MrUnix (May 18, 2012)

All the Lincoln welders (and Miller, and Hobart, and….) will have the recommend supply wiring size and circuit sizes listed in the manual. My Millermatic states a minimum of 10ga wire and 30A circuit (@230VAC). A Lincoln Pro Mig 256 lists a 60A circuit. The new Lincoln stick welders (AC-225) specify 10ga and a 50A circuit.

Cheers,
Brad


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## WhyMe (Feb 15, 2014)

> As a side note: I did find my NEC and there s a caveat to the 28a table value * 125% that drives a 40a/8g branch. NEC-430.6-exception3 states that if the motor has a plate that lists HP and amps, you ignore the HP and table values in favor of the plate s FLC to size branch conductors.
> - TripH


 430.6 exception 3 applies to motor operated appliances where the appliance itself has a name plate that list the full load current. Such as a refrigerator, washing machine, etc. The data plate on a motor on the compressor is to the motor only and the compressor in total is not considered a listed appliance and does not carry an appliance data plate.. If the motor data plate has the HP and FLC then the HP is to be used. If the motor data plate only list the FLC then the FLC is used to interpolate the HP.


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## TripH (Feb 26, 2016)

Good clarification. I 'assumed' that since the exception was in 430.6, the 'plate' would be a motor plate. Had the exception been in 420, I would have 'assumed' it applied to overall appliance. Live and learn…

As for why I passed inspection on 10/2 Romex and 30a breakers-- maybe you're right and the inspector might not have the nuances for residential. Or maybe he just used FLC (I can't remember if he looked at the motors or not). Or maybe because it's a hobby shop, he applied continuous duty to the DC and intermittent duty to everything else? He did ask if it was a hobby or home-based business… Just don't know what logic he applied… I just wanted the ticket. I will say, he looked-over my 3-phase setup at some length… I started to get rather nervous…

I'm very tempted to call the compliance dept and ask-but what a potential can of worms. Maybe I'll just get that burn phone first


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## dddddmorgan (Apr 24, 2015)

Well I messaged the nephew and he said pull 10/2 for the outlets if you want, 12/2 for my run would work fine also, and he said he had enough 6 that he could run my welder outlet.

I told him "ok, but if I have to get in the attic I'm drinking the whiskey!"


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## WhyMe (Feb 15, 2014)

TripH, I wouldn't worry about it. If your setup passed inspection then you're covered. The NEC in a lot of cases is overboard on the side of extreme safety.


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## TripH (Feb 26, 2016)

It's not about worrying about my wiring. It's inspected and certainly safe. In almost twenty years, I've never popped a 30a breaker with 5HP tools - and I've processed a lot of 12/4 rock Maple in my time…

It's more about my curiosity (I'm just built that way-I just like to know the 'why')-- and that I've been endorsing 10/2 for 5HP for years. I'm sure it's safe in a hobby environment, but I don't want to continue with that recommendation if it's against code. I get the nature of woodworking tools rarely approach even ½ FLC, so it's not really a safety thing. It's more about endorsing 10/2, then some poor guy gets inspected and has to rewire. That would suck.


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