Running 120v Mig Welder on 220v Outlet  - Page 1
Forum section: electronics / beginners

author: electromateria
author_rank: Regular Contributor
timestamp: March 31, 2023, 01:54:51 pm
content: My mig welder requires 120v and pulls max 25 amps. I want to run it off my dryer outlet power source. My plan is to run a regular dryer plug in the outlet and wire it into my mig welder, using only 1 of the hot connections. I asked chatgpt about the plan and it said:QuoteTo me it just sounds like it's talking a bunch of nonsense, so I figured to be safe I'd ask the real experts before moving forwardWhat you guys think?

author: langwadt
author_rank: Super Contributor
timestamp: March 31, 2023, 03:58:37 pm
content: is the wire size for the neutral smaller than for the hots?

author: electromateria
author_rank: Regular Contributor
timestamp: March 31, 2023, 05:05:41 pm
content: Quote from: langwadt on March 31, 2023, 03:58:37 pmIt's standard 10/3 electrical wire. Pics attached.The black 10/3 wire is from an old dryer. The orange is new 10/3 romex.

author: paulca
author_rank: Super Contributor
timestamp: March 31, 2023, 07:14:54 pm
content: Given this is the beginners forum and we talking about fatal voltages...If you have any doubts about your wiring >100V, you need a local professional. Not nerds on the internet.The best part is... if anyone is going to get electrocuted it will be them and not you.If you feel studied enough that the above does not apply, then why are you asking?

author: jonpaul
author_rank: Super Contributor
timestamp: March 31, 2023, 07:17:38 pm
content: try a professional electricians forum, Mike Holt forum.Use of one side,of 240 V connection is poor practice.A welder on any household circuit will induce,severe flicker and transients on the same line and breaker panel bus.Jon

author: jpanhalt
author_rank: Super Contributor
timestamp: March 31, 2023, 07:32:25 pm
content: Quote from: electromateria on March 31, 2023, 01:54:51 pmIt's not nonsense. From a block diagram point of view, your welder will have the welder circuit, and a circuit for everything else. Is the welder portion a heavy duty transformer? Will it survive 2X the current, which equals roughly 4X the wattage (i.e., W = I^2R for purely resistive loads). The everything else, includes controls and so forth. If they are not designed for 220V, they will pop. Do you have an electric clothes dryer or stove? The heater part is 220V, everything else is probably 110V. The light bulbs in each would burn brightly but not last the night if fed 220V (credit to Edna St. Vincent Millay, 1920).Your error in buying a 110V welder based on sales videos won't be fixed by plugging it into 220V. Remember, most Asian imports are stressed even at their published ratings. Going beyond that present real risk. At a minimum, you will destroy the unit.

author: Jwillis
author_rank: Super Contributor
timestamp: March 31, 2023, 07:52:57 pm
content: The following instructions are based on the ability and competence of end user. If you feel you don't have the competence or knowledge then do not attempt procedures on your own. Please consult a professionally electrician for guidance.Nothing personal.Are you competent enough to add a 20Amp circuit to your breaker panel? I added one and run my MasterCraft wire feed MIG on that without any problems. My friend operates his Lincon Wire feed as well without any difficulties.If you can't install a 20 amp circuit then there is no regulation that states that you can't draw 120V 30amps from a dryer plug. NEC regulations and recommendations End at the outlet. What you plug into that outlet is up to you and at your own risk.With that being said all you need is the following information.The minimum requirement for dryer plug and wire is 30 Amps at 240V.Each 10 Awg wire is rated for 30 amps.The dryer plug has 2 Lines(live) 120V each , One Neutral(common) and one Earth ground. Connecting line to line is 240V 30 amps. Common is not used. . Connecting any One of the lines to Neutral(common) is 120V 30 amps .You cannot use both 120V lines at full load of 30 Amps each since you only have one Neutral(common) wire rated for 30 Amps.It's unorthodox to used only one 120V line from a dryer plug but not restricted as long as the load does not exceed 30 amps.In fact there are no regulations dictating that you cannot draw more amps on a circuit of a specific rating. It is recommended that you don't increase breaker amperage rating because of potential risk of fire.But I your case you will be OK as long as you use Only One of the 120V Live Lines and the Neutral Common.Consult the pinouts of the cord and plug and check continuity of each wire and label accordingly.If your using a ready made cord. the unused Live wire needs to be terminated and insulated from all other wires and chassis. A simple crimp termination or marette would be fine. You can tape the crimp or marette for added insulation. Be sure to connect the earth ground to the chassis of the welder.Hope that helps. And be carefull.

author: jonpaul
author_rank: Super Contributor
timestamp: March 31, 2023, 08:42:44 pm
content: Please see NEC and local electrical codes, most mains connectors, and breakers are de rated eg à 20 A,circuit should not have over 17A loading.Overloaded electrical are fire hazards.Your insurance policy may be invalided if an incidents or loss occurs, due to modification of the systems that is not by a liscenced electrician, or that violates NEC or NFPA code.Jon

author: Jwillis
author_rank: Super Contributor
timestamp: March 31, 2023, 10:47:53 pm
content: Quote from: jonpaul on March 31, 2023, 08:42:44 pmTrue that breakers are rated at 80% of listed value, but will not break instantly at that 80% value. You can operate a 30 amp breaker for limed time at over 80%25 amps on a 30amp circuit is 83% . It will work fine without over heating the 30 amp circuit. I can weld just fine on a 20 amp circuit at 120V with no heating of circuit or breaker.Since the plug is modified by only using 2 of the three lines and not the outlet then no regulations are broken. As said before the NEC recommendations stop at the outlet. NEC regulations and recommendations do not apply to loads that are not permanently connected to a circuit. This includes appliances and welders.In Canada you do not need a licensed electrician to install a circuit. Only an inspection may be required if they show up.

author: electromateria
author_rank: Regular Contributor
timestamp: April 01, 2023, 02:20:27 am
content: Quote from: Jwillis on March 31, 2023, 07:52:57 pmHuge help! Appreciate ya!! The chatbot threw me off with it's nonsense and I needed to make sure.Don't worry, I'll be very careful and take my time.. plus it's a relatively simple job. I understand the risk involved.Any time I don't feel confident, or understand at a level that will keep me safe, I won't move forward.I'd love to install new breakers and circuits, I'm sure I could do a very clean job, but the forum already made me realize that's a bad idea because of insurance / liability issues.

author: tychob
author_rank: Contributor
timestamp: April 01, 2023, 04:25:40 am
content: Quote from: Jwillis on March 31, 2023, 07:52:57 pmThis is not necessarily true, there's a concept called a MultiWire Branch Circuit. Seehttps://twielectric.com/national-electrical-code-multiwire-branch-circuit/Because of the fact that the two 120V hots are 180 degrees opposed phases, the currents on the neutral from the two lines (mostly) cancel, so each hot can be used up to the full 30A rating, even though there is only a single neutral is only rated up to 30A. You still need a common trip breaker though like a 240v circuit. However its not useful for a single device, because you can't use two hots without a transformer anyway.So long as the dryer outlet is a correctly wired 14-30, and not a 6 or 10 series or something else with a messed up ground, the neutral load shouldn't be a problem to wire up a plug with one hot just not connected.

author: Jwillis
author_rank: Super Contributor
timestamp: April 01, 2023, 07:51:37 am
content: Quote from: tychob on April 01, 2023, 04:25:40 amThat configuration does not apply to a dryer nor a electric stove outlet on a split phase system. Regulations dictate that a dryer outlet can be no less than 30 Amps and range outlets are no less than 40 Amps , The outlets described in the link you provided is for 120V 15 Amp outlets. Dryer and stove wiring is 10 AWG not 14AWG.On a split phase system the transformer outside has a primary with Hot and Neutral . On the secondary has Three wires Hot neutral hot , exactly the same as a transformer with a single coil primary and a centre tapped secondary. Yes relative to neutral or centre tap each 120V winding is 180o. But the two taps from either end of the secondary coil is 0ophase 240V.

author: Jwillis
author_rank: Super Contributor
timestamp: April 01, 2023, 07:53:48 am
content: Split phase to a residence is set up exactly like the diagram below.

author: james_s
author_rank: Super Contributor
timestamp: April 01, 2023, 07:56:17 am
content: Quote from: jonpaul on March 31, 2023, 07:17:38 pmThey won't help you. That forum is for professional electricians only, nobody else is welcome and giving advice to us ordinary serfs is strictly forbidden.

author: langwadt
author_rank: Super Contributor
timestamp: April 01, 2023, 09:10:41 am
content: Quote from: Jwillis on March 31, 2023, 07:52:57 pmtwo 30A 120V load are the same as a single 30A 240V load, no current in the neutral

author: EPAIII
author_rank: Super Contributor
timestamp: April 01, 2023, 09:42:55 am
content: I don't understand. You seem to be showing coils of wire on a workbench. The question is what is the wire IN THE WALLS between the breaker box and the dryer outlet. That is what counts, not some extra wire you have sitting around.This is not a shock hazard situation. It is a FIRE hazard. If the neutral conductor is too small, it can heat up and start a FIRE inside the walls. You don't want that. There could be a delayed reaction. It may work OK for minutes, hours, days, weeks, months, even years and then, ONE DAY you are standing on the curb looking at the smoking ashes that the fire trucks are hosing down. And wondering if your insurance payments are up to date.You obviously do not know the issues involved. If you want to do this, get a qualified electrician to inspect the wiring. But I would just have a new circuit installed for the welder. Money well spent!Quote from: electromateria on March 31, 2023, 05:05:41 pm

author: sokoloff
author_rank: Super Contributor
timestamp: April 01, 2023, 11:18:43 am
content: Quote from: Jwillis on March 31, 2023, 07:52:57 pmYou can use both simultaneously at the rated amperage. If you use both at once, there is current in both line wires and none on the neutral. If you use only one, there is current in one line wire and on the neutral and none on the other line. Pulling 25A @ 240V causes the same amount of heating in the supply wires as pulling 25A @ 120V or as pulling two different 25A @ 120V loads on opposite legs. (Imagine a massive 10 ohm resistor with a center tap. Connect the ends across the 240V supply. Everyone agrees that 24A will flow through the resistor and each of the supply lines. Now, connect the center tap of that resistor to the neutral. Nothing changes.)Quote from: Jwillis on March 31, 2023, 07:52:57 pmThis is true but slightly misleading. As above, you would also be safe if you used both 120V lines with the full rated amperage at the same time.Quote from: tychob on April 01, 2023, 04:25:40 amThis is overwhelmingly correct, except for a small detail in the part I added italics to. You only need a common-disconnect breaker, not a common-trip breaker. (Two single breakers connected with an accepted/recognized handle tie will suffice; those will be commondisconnectbut not commontrip.)Quote from: EPAIII on April 01, 2023, 09:42:55 amThe dryer outlet is on a 30A breaker and fed with 10/3 wire in the walls (assuming the building was built to code). The duty cycle on a small mig welder is so low that there is no fire hazard here. I wouldn't be surprised if the welder's power cord had 14 or even 16 gauge wire.

author: sokoloff
author_rank: Super Contributor
timestamp: April 01, 2023, 11:22:22 am
content: If you've got a lot of shop type projects coming up, I'd recommend having a look at garagejournal.com. They have a lighting/electrical forum that is filled with the typical mix of people who know what they're talking about and people who distinguish themself as not being those people, but it's way more friendly to DIYers than Mike Holt's or HeatingHelp.

author: jonpaul
author_rank: Super Contributor
timestamp: April 01, 2023, 12:33:37 pm
content: .... a 240V outlet is not designed for 120V unbalanced load. Neutrals may be same or smaller guage wire than the L1, L2.James,we have used Mike Holt and electricians forums for years with fine advice and research.No requirement for professionals only.https://www.mikeholt.com/has seminars, courses, products and a forum.Mike is a scion of electric safety and compliance.Jon

author: barshatriplee
author_rank: Regular Contributor
timestamp: April 01, 2023, 02:21:40 pm
content: I think you have to use a 3000 Watts AC Voltage Converter Transformer 220v to 110v.

author: tychob
author_rank: Contributor
timestamp: April 01, 2023, 02:58:31 pm
content: Quote from: jonpaul on April 01, 2023, 12:33:37 pmFor a feeder this is allowed to a certain extent, but this is a branch circuit. If the circuit is to code (which may be an unreasonable assumption) then by my understanding the neutral wire is required to be equal to the maximum branch ampacity, specifically in case the user plugs in an unbalanced load in future. Seehttps://forums.mikeholt.com/threads/neutral-of-a-branch-circuit-be-reduced-in-size.149599/

author: Jwillis
author_rank: Super Contributor
timestamp: April 01, 2023, 05:35:43 pm
content: Quote from: langwadt on April 01, 2023, 09:10:41 amYes you are correct . My mistake.

author: james_s
author_rank: Super Contributor
timestamp: April 01, 2023, 06:30:10 pm
content: Quote from: EPAIII on April 01, 2023, 09:42:55 amThis should never happen. You will never find a 240V outlet with neutral (in the USA at least) where the neutral conductor is smaller than the live conductors. The two hots are 180 degrees out of phase so they can't be used together to power a single 120V load and the load on the neutral wire can never be higher than that carried by one of the hot wires.I have never seen a 120V-only welder that draws 25A though so I'm skeptical of this whole deal. The biggest standard 120V receptacle is 20A, there are 30A and larger sizes used for boat and RV shore power but that would be a strange choice for a welder. Are you sure the welder isn't dual voltage? I had one that could be set to 120 or 240V.

author: Monkeh
author_rank: Super Contributor
timestamp: April 01, 2023, 06:30:53 pm
content: Quote from: jonpaul on April 01, 2023, 12:33:37 pmThe NEMA 14-30 is in fact designed to handle full load current on all contacts, and 10/3 wiring will provide the same gauge wire for both lines and neutral.

author: Jwillis
author_rank: Super Contributor
timestamp: April 01, 2023, 06:59:18 pm
content: Quote from: james_s on April 01, 2023, 06:30:10 pmThey're light application welders with a 20 - 30% duty cycle. They can be either stick or wire feed . Wire feed come with flux core wire but can be outfit with regulator for CO2or Argon . Depends what your welding steel or aluminum.https://ch-delivery.lincolnelectric.com/api/public/content/6962ab0875394b6983c4ee36019ec119?v=6827a082orhttps://ch-delivery.lincolnelectric.com/api/public/content/607c8be3007042339a4707f1571b9907?v=303b9338Some are convertible to 240V some are not. Not sure what brand the OP has but he should check to see if his is convertible to 240V. That would be the easiest most logical solution.

author: Stray Electron
author_rank: Super Contributor
timestamp: April 01, 2023, 11:26:48 pm
content: Quote from: langwadt on March 31, 2023, 03:58:37 pmNot in the US. If he's using commercially made cable (Romex or something similar) it will be the same size. IIRC the ground conductor is allowed to be one size smaller since it's not normally a current carrying conductor. Canada probably has the same rule but you'd have to check.I agree with James, I'm skeptical that the OP's welder only draws 25 Amps. My small welder draws up to 33 Amps at 120 VAC.I've said it before and I'll say it again, if you want to weld, get a 220 VAC welder and run it on a 220 VAC 50 amps circuit (minimum). 110 VAC welders are nothing but toys.

author: Stray Electron
author_rank: Super Contributor
timestamp: April 01, 2023, 11:37:33 pm
content: Quote from: jonpaul on March 31, 2023, 08:42:44 pmYou're wrong about that. There's no such rule in the NEC (U.S. National Electrical Code) and in fact, the NEC allows welders (specifically) to be run on circuits that are slightly smaller (up to 10% IIRC) than the circuit rating since they don't run continuously.There is no de-rating of at any voltage or current in the NEC that I've seen. EVERY circuit constructed in accordance with the NEC should be able to carry it's full rated power. Otherwise, what would be the point of setting requirements if the circuits couldn't meet their specifications.

author: Stray Electron
author_rank: Super Contributor
timestamp: April 01, 2023, 11:44:46 pm
content: Quote from: james_s on April 01, 2023, 07:56:17 amGo ask on some of the welder forums such as Miller Welds. They cover stuff like this all of the time and many of those folks make their living with AC power so you'll get a lot more knowledgeable answers there than you will here.

author: sokoloff
author_rank: Super Contributor
timestamp: April 01, 2023, 11:58:26 pm
content: Quote from: Stray Electron on April 01, 2023, 11:37:33 pm210.19 covers conductor sizing and over-current protection devices.For continuous loads (loads that can persist for more than 3 hours), the default is that the circuit must be sized to 125% of the continuous load. There are other factors which apply, but this is the source of the often quoted “80% rule”.It obviously does not apply here for a welder. (And you’re right that every circuit is rated to carry a certain ampacity, but there are cases where that is then de-rated to 80%.)

author: Stray Electron
author_rank: Super Contributor
timestamp: April 02, 2023, 12:15:31 am
content: Quote from: jonpaul on April 01, 2023, 12:33:37 pmWrong and Wrong. It depends on what kind of 240 VAC outlet you're using (and assuming that you're using the proper breakers and wiring for that outlet). Some 240 VAC outlets such as Nema type 6 are 240 volt only and only connect L1 and L2 (and the safety ground) and can only supply 240 VAC circuits. Other outlets supply (NEMA type 14) both L1 and L2 and also have a Neutral (and the safety ground). Those outlets and circuits can and routinely DO, operate 120 VAC circuits. It's quite common in large appliances for the heating elements to run on 240VAC but the control circuits to run on 120 VAC. Many of Miller's large welders do the same.Neutral wires are not allowed to be smaller than the L1 or L2 conductors in the NEC. Period. Neutral wires by definition are current carrying conductors and have to be able to carry the same current as L1 or L2. If neutral isn't needed (such as a purely 240 VAC circuit) and all of the current is carried in L1 and L2 then the neutral wire is usually totally absent. There is simply no case for having a neutral wire smaller than L1/L2.The OP should be using a NEMA type 14 plug and socket to safely tap 120 VAC from his 120/240 VAC circuit. I haven't seen what plug and socket he's attempting to use but from his description it's probably a NEMA 14-30, either R or P. Seehttps://acupwr.com/pages/nema-chartZoom in so that you can see the circuit designations for each contact in the outlet. X,Y, W, G = L1, L2, neutral (White wire) and ground respectively.

author: james_s
author_rank: Super Contributor
timestamp: April 02, 2023, 01:37:23 am
content: Quote from: Stray Electron on April 02, 2023, 12:15:31 amIt used to be permissible to use the safety ground as neutral for small loads, my clothes dryer is set up this way, the timer motor and drum light are 120V and my house built in 1979 has no neutral on the dryer circuit. At some point this changed though and isn't allowed any more, modern dryer installations have a 4 wire receptacle.

author: tychob
author_rank: Contributor
timestamp: April 02, 2023, 10:20:02 am
content: Quote from: james_s on April 02, 2023, 01:37:23 amIts actually the opposite. It used to be legal to use the neutral as a chassis potential for ovens and dryers specifically. This setup used a NEMA 10 connector and had the chassis bootlegs at the appliance. This was an exception put in place first to allow use of cable stocks without a ground and then grandfathering 3 wire setups. At no point has it been legal to use a ground as neutral. (The logic was since these appliances don't move often, proper grounding wasn't important). If you had a NEMA 6 and uninsulated ground wire, that wasn't to code to attach a 4 wire dryer. It was also never to code to use a NEMA 10 and call it a ground, but pre-2020 meter-main bonding, the difference between a neutral and an insulated ground wasn't always easy to tell.There is a completely separate exception that is still allowed that allows electric lighting control switches to use ground as neutral for up to 0.5mA of current, in order to allow for installations in switch loops where no neutral is available. However, that is much smaller loads.

author: Jester
author_rank: Frequent Contributor
timestamp: April 02, 2023, 04:12:34 pm
content: Quote from: Stray Electron on April 01, 2023, 11:26:48 pmI'm going to disagree with this statement. Sure if your a welding shop. For home use my Hobart MIG 240V on 30A circuit deals with everything I throw at it and has for years. Never tripped the breaker.

author: electromateria
author_rank: Regular Contributor
timestamp: April 02, 2023, 04:57:38 pm
content: Quote from: EPAIII on April 01, 2023, 09:42:55 amStandard 10/3 in the walls, similar to whats in the images.Thinking logically here, if my mig welder pulls MAX 25 amps @ 120v (says 20-25amps) and my dryer can pull closer to 30 amps @ 240v, how is it that my welder is a concern based on the size of the neutral wire? If the dryer doesn't burn the house down how's the welder going to when it's drawing even less power? I'm not understanding the point of concern from that angle.Quote from: Stray Electron on April 01, 2023, 11:26:48 pmI have a large tombstone stick welder that can draw 50 amps at 220v. I need to setup the mig welder because I'm doing autobody work with 18g steel. With stick I'm having blow through issues, even at lowest setting, reversed polarity, 1/16th rods, etc. Mig is better for what I'm doing, don't care about pushing amps and penetration since I'm working with thin material. That would actually be a problem for me.

author: electromateria
author_rank: Regular Contributor
timestamp: April 02, 2023, 05:02:25 pm
content: attached images

author: james_s
author_rank: Super Contributor
timestamp: April 02, 2023, 06:50:01 pm
content: Quote from: Jester on April 02, 2023, 04:12:34 pmI also use a MIG welder on 240V 30A and it's fine, but I agree that 120V is insufficient, at least it is if it's only a 20A circuit. I used to have a stick welder that was dual voltage and on 120V it could only weld thin materials using those piddly little scrawny rods, it was an exercise in patience too, stick welding is tricky enough as it is, but it gets more difficult to strike and maintain an arc at lower currents.

author: james_s
author_rank: Super Contributor
timestamp: April 02, 2023, 06:54:08 pm
content: Quote from: electromateria on April 02, 2023, 04:57:38 pmIt's not. People are getting confused because there are situations where the neutral can be smaller than the live conductors, this is not one of those situations.There has also been some confusion around the unusual nature of the 240V split phase topology used in North American homes. You cannot put both hots in parallel, draw double the current and overload the neutral because the hots are 180 degrees out of phase. If you load up both hots the load cancels out, the neutral carries ONLY any unbalanced load that is present.Just use it, it's fine, you can pull 30A at 120V by using one hot wire and the neutral. Do not do this if you have one of the old 3 prong dryer sockets where there is no neutral, only two hots and ground. It will work, but it's not safe.