Welder requires 230v/50a, what do I do?

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  #1  
Old 05-09-06, 04:31 PM
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Welder requires 230v/50a, what do I do?

Hi all,
So I went on a shopping spree this past week for a couple goodies i've been meaning to get for a while. I got a 60gal 240v 1phase air compressor and a lincoln electric MIG welder.

The air compressor came bare, I was supposed to have a professional wire it up, but i've been a DIY all my life. I went to home depot and bought some 3-wire electrical cable and wired it to the compressor. They didn't have a 240v/20a plug for some reason, so i'm going to check at another home depot today. They sell the twistlock stuff, but my receptable isn't twist lock. Do you suggest I upgrade my wall outlet to twistlock, or just find the non-twistlock 240v/20a plug?

Now... the welder is going to be a different story. It seems I neglected to read the specs because the welder comes with a 230v/50a plug. As far as I know, my garage outlet is only 20a, but I did notice that the breaker box has 2x 20a breakers with a single-throw switch for the outlet I speak of. What's the best way to provide a safe 230v/50a supply for my welder?

Thanks in advance!
 
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Old 05-09-06, 05:07 PM
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Most welders come with a typical plug (NEMA 6-50P) for a standard welder receptacle, which has historically been the NEMA 6-50R. Just because this is a 50A plug, does not mean your machine needs a 50 circuit. The manual tells you what breaker you need; and then wire it accordingly. You can even change out the plug if you want. Which Lincoln did you get? If it's something like the SP-175, you only need a 30A circuit, for example.
 
  #3  
Old 05-09-06, 05:11 PM
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What gauge wiring is on that 20A circuit in the garage? With the duty-cycle limitation on the typical welder, you may be able to use the lighter gauge wire and change out the breaker to a 30A.

This is often discouraged in residential use, and I would only recommend it if you fully understand the duty cycle limitations and that the receptacle and breaker be labeled for welder-use only, and there must be no chance of someone else using it for something else in the future.
 
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Old 05-09-06, 05:38 PM
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Thanks for that info!

After posting this, I had done a little bit of research and my wall outlet closely resembles the NEMA 6-15 or 6-30 configuration. Someone wrote 240v/20a on the wall next to it, but that doesn't sound entirely accurate. If I had to make a guess at the gauge on the outlet, it looked to be around 10-12ish. I also noticed that the breaker box uses dual 20a breakers (both attached by a single throw switch). Does it sound more likely that my outlet is NEMA 6-30? From the pictures, 6-30 appears to be smaller than 6-15.

Oh - and yes, my welder is the SP-175
 
  #5  
Old 05-10-06, 11:15 PM
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For the 175A welder a number 10 wire and a 30A breaker, Lincolns manual leaves something to be desired unless they changed it. That machine uses 20A wide open which I doubt you will ever get to but the recept, a 6-50-R is listed for use with wire down to 10 and you can even do long runs without affecting performance.
 
  #6  
Old 05-11-06, 10:24 AM
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The lincoln manual specifies 75C #8 awg copper and 40 amp breaker or super lag fuse for the 175 welder (mig) using a conduit method.


http://content.lincolnelectric.com//...r/im/IM797.pdf
 
  #7  
Old 05-11-06, 11:02 AM
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Yes it does and we suspect someone was sniffing the circuit board varnish when they wrote that up especially since the 250A machine allows for 10 wire with 50A breaker. In the real world that machine runs about 15A draw running 030 wire about as fast as the machine will handle it and a hobbyist wouldnt likely be able to tune or dial the machine above that. That tech info may have been written before the advent of more modern breakers where they would have likely had to over fuse it for surges and a smaller breaker certainly wont hurt a thing. The 210-215 class machines are rated to run on 10-30 circuits and we run these on the same. I would prefer to run lighter breakers, closer to the real demand of the machine, the other is the max allowable breaker providing you run the number 8 wire, I also like the number 10 for extension cords. I normally follow manuf instructions or beyond but they really goof up on that one considering that it is also a 30% duty cycle machine at best and they got it supplied for a 250 class machine. Art 630 applies to welding machines. That machine or a model similar to it has been around a long time, it is very well proven and considered tops in its class. Hobart and Miller make one similar and their wiring specs are more in line with the demands of the machine but I wouldnt follow the minimums and the manuals are confusing at best, really written for the professional electrician well versed in code and NEMA specs. I would like to see them re-written in common easy to understand language with the minimum wire size upgraded. They list a 30A max breaker but in reality they are allowed for use with 50A circuits,,, but not with the minimum wire size listed. Same with the 175 Lincoln, it comes with number 12 cord and a 50A plug, allows it for use on 50A circuits.
I am going to add one more thing, these little machines come with their own internal thermal protection which covers the cord and the interanls of the machine, the breaker in this circuit is primarily for short circuit interuption which allows for plugging into heavier circuits.
Mac 702 who posted in this thread may want to elaborate further if there is an interest as these machines are becoming so much more common in home shops and Mac is intimately familiar with the requirements of most makes and models which would be found in a home shop.
 
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