Question on 300 amp class AC/DC TIG machines and single phase

So, I just got done posting a rant in the general section on used equipment prices and I forgot to mention that if you're looking for a heck of a deal, go ahead and score yourself a 3 phase unit. They're actually usually realistically priced, but good luck powering them:P:P:P. But seriously, what's the deal with what I call "the 300 amp barrier" Almost nobody out there is offering a 300 amp inverter capable of being powered by single phase electric. Case in point are the 315 EX and EXT. Given that 250EX draws an inrush max of 45 amps on single phase input, it would go to surmise that the 315, if configured for single phase would theoretically need a max of only 56.7 amps to allow full output. Lacking an electrical engineering background, I'm curious what it would take to produce a single phase 315, and why it hasn't been done here. 3 of the big 4 manufacturers out there have offered 300 amp inverters at one time or another, recently. But they haven't been marketed nearly as agressively as the 200 amp machines. In fact, one brand opted to leave their 311 amp inverter out of their product catalog for a year or 2, while another brand discontinued it's 300 amp inverter altogether, leaving people needing that class the option of their 350 amp machine which enters OBSCENE price levels. One of the big 4 has never offered a 300 amp inverter unit while the last has offered theirs, albeit quietly, for a good number of years. Everlast has had the 315 in 3 phase-only, at least since I've known of them.

So what is it? Is it a durability issue? Is there some kind of threshold reached at 300 amps? Is it production costs? I guess I don't get it.

The reason I ask this question (besides it being on my list of things to talk about on this forum to keep it INTERESTING and alive), Is that when I struck the deal for my 250 EXT, I was informed that there was a possibility that a 315EXT could be delivered (at the time) immediately, but I needed 3 phase to hook it up to. I asked the cabinet shop 2 doors down what it would run me to get 3 phase (which he has) run over to my building. He figured in the ten grand range....probably not this week:P

doesnt the electric company charge like a lot more if you want to be hooked up with 3 phase

if your shop doesent have 3 phase already wired in, yes it is expensive to put 3 phase in. i asked my elertician buddy and he said depending on the job, anywhere from 2000 and up. and thats just for the converter thing to go from single to 3 phase, wouldnt even want to guess labor on that.

Charges depend on how far away the 3 phase has to be run. If you live close enough to its path, its not too bad, if you are serious about it....But it costs major money to rewire.

There are some downsides to 3 phase, I have it in my shop, first is the cost, a local welder just built a new shop 1/2 mile from mine, his cost for a pole, transmformer and shop wireing, $25,000. Next is supply voltage,,, 3 phase is 208 volts when using single phase out of it,,,,that kept my 250EX blowing the 40 amp breaker,,,others can run a 40 amp breaker on single phase with 230/240 volts. Took me a while to figure that out....Then there is the plug versus hardwireing, single phase you can use a plug ,,,,3 phase welders etc are gennerally hardwired to a single location in the shop...3 phase is good for stationary large users like compressors or milling machines with large motors etc...for most people a single phase welding unit is more practical.

In the US, three phase typically comes in 208, 220, and 460. Then you have Delta and Wye systems...which even confuse me. Delta will typically have one leg though that when measured from pole to pole will give the nominal voltage...but when used to ground/common as you would for single phase gives a much higher reading. Wye, will typically give the same reading on all legs to ground/common so that any leg can be used. MOST of the time Wye systems are 208, and give roughly 110V to ground, but 208 to any given hot leg. 240 Delta, will give 240V between give 240 Volts between any given hot leg, but one leg will be in excess of 200 Volts to ground/common. I like 240 Delta because it is fairly common around many rural and agricultural areas around here, but you do end up with several "high leg" circuits if you are running a bunch of single phase circuits. There are some products that can utilize the high leg voltage though like light fixtures (special ordered). 208 is slowly disappearing...Yes, some of you may have it, but 240 Delta is being offered by many more EMC's and local power companies than ever....And 460V is the one being installed in most newer industrial parks and factories. There are a couple others, but rarely found or supplied.

All the delta systems I have seen use a ground...I think...never paid attention to it, but the ones I have particpated with do. Most of the 460 installations are delta as well. I am not a industrial electrician, but I have one as a friend. :P But dealing with customers all the time, all across the country, it seems 208 is silently slipping away and new installations are 240 or 460 Delta.

However, most items I have seen don't care what that third leg is doing, including electrical motors and welders that I have fooled with. I do know that there are some things that do...But never ran across them in my experience. Ken, which "loads" are you referring to?

As I mentioned, most all I have come across don't mind either if it can operate on 208, including our welders.

Thanks all for the info. As far as I know the electrical service on my small town (Rockville, MN) is OLD. I don't know if that means it's delta or wye, or 208, 220, 460. I do know that when I put a volt meter across each leg of my 30 Amp outlet, I get about 123 volts per leg. I will be in contact with the local utility company in the near future, as it looks like a Bridgeport mill (complete with prototrak cnc capability) may be in my near future:D:D. But one question remains unanswered. Does Everlast have plans to offer either of the 315 Amp TIG welders (or an altogether new 300 Amp model) with single-phase input, as an option in the near future? This won't change my mind as far as getting my 250EXT, just wondering.

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Originally Posted by hooda

Thanks all for the info. As far as I know the electrical service on my small town (Rockville, MN) is OLD. I don't know if that means it's delta or wye, or 208, 220, 460. I do know that when I put a volt meter across each leg of my 30 Amp outlet, I get about 123 volts per leg. I will be in contact with the local utility company in the near future, as it looks like a Bridgeport mill (complete with prototrak cnc capability) may be in my near future:D:D. But one question remains unanswered. Does Everlast have plans to offer either of the 315 Amp TIG welders (or an altogether new 300 Amp model) with single-phase input, as an option in the near future? This won't change my mind as far as getting my 250EXT, just wondering.

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On some of the older cnc mills, the only thing 3-phase is the motor. Very easy and affordable to convert to single phase with a VFD.

I would say that is wye 120 volts to ground 208 across phases. Most power companies will build what you want its all about the transformers and way they are wired as long as there is three phase primary in area.

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Originally Posted by geezer

3 phase is 208 volts when using single phase out of it,,,,that kept my 250EX blowing the 40 amp breaker.

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kinda off topic, but why didnt you just wire your 250 to 3 phase if you had it instead of single phase? im sur eyou got it all figured out now, but kinda curious.

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Originally Posted by jerky

kinda off topic, but why didnt you just wire your 250 to 3 phase if you had it instead of single phase? im sur eyou got it all figured out now, but kinda curious.

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No advantage to 3 phase on the 250EX, for me,cause my shop has 2 plugs one at each end and I didn't want to have it hardwired in one location, plus I have another welding plug on a pole 60 feet from the shop for outside welding,,I could have wired the 250EX and my PP80 to 3 phase but I like the portability,,,single phase plugs let me use my IMIG 205 or MY PA 200,,,,saving the 3 phase part for when I upgrade my compressor,,,,If I was a pro welder earning a living at it I would probably use the 3 phase more,,,,but being just a hobby type guy,, single phase gets me by.