Welding machine extension help

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  #1  
Old 09-28-05, 10:06 PM
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Welding machine extension help

I had a 220v 30amps dryer outlet in my garage NEMA 14-30P 4 prong, and the welding machine millermatic 175 comes with 3 prong NEMA 6-50P that draw 19.5 amps, so the 4 prong one have 2 110v, 1 ground and 1 neutral, the 3 prong one have 2 110v and 1 ground.

So instead of changing out whichever side outlet/plug to make it fit, I just make a 50 ft extension cable, it is a 10/3 with 4 prong male plug that goes to the dryer outlet and female 3 prong outlet for the welder to plug in, also on the 4 prong male plug, since I don't have a neutral wire, I just leave it un-wire, I am using the black and white for 110v and the green for ground.

Did you guys see any problem here?

My second question is--what is the differene between ground and neutral, because they both end up on the ground bar?
 
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  #2  
Old 09-29-05, 06:11 AM
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Yes, I see a problem. The welder needs a 50 amp circuit, and your dryer circuit is only 30 amps. Plus, you are using an extension cord where permanent wiring is called for.

Do this properly, run a new 50 amp circuit to where you need the welder.

The difference between the ground and the neutral is that the neutral carries current, whereas the ground does not (except in the event of a failure).
 
  #3  
Old 09-29-05, 07:20 AM
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I don't have the welder yet, but the online manual sat 30amps, 14 AGW up to 67ft in length. Why 50 amps?
Thanks
 
  #4  
Old 09-29-05, 07:55 AM
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The NEMA 6-50 P is a 50 amp plug. Are you sure that you got the plug information correctly?
 
  #5  
Old 09-29-05, 10:13 AM
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Originally Posted by CBR900RR
I don't have the welder yet, but the online manual sat 30amps, 14 AGW up to 67ft in length. Why 50 amps?
Thanks
Welders are different duck than other equipment. If we size the conductors accorrding to 630.11 for an arc welder (which this is) we could use a minimum of 14 awg copper cable or individual wires in conduit. You sometimes need to be careful between cable (NM-B) and individual THHN wires in conduit due to ampacity differences. Code would allow you to use an inverse time breaker or fuses for overcurrent protection up to 200% of the ampacity of the conductors as calculated in 630.11(a) 2005 NEC. This would allow you to use a maximum 30 amp breaker based on 30% duty cycle. I dont believe your welder has a higher duty cycle if it is typical. What is the welders duty cycle? Do you know what output amperage the duty cycle is based on? You will also have overload protection at the welder, usually there is a reset button on the back of the case.
So in a nutshell you can use your dryer outlet capping off the neutral if your welder falls within the parameters I mentioned above and that outlet is dedicated to the welder. You must change the receptacle to a 6-50R. You cannot modify extension cords in the matter you suggest. Refer to the owners manual for using extentsion cords! Your 10 awg wire is fine if this is a typical dryer circuit. It doenst do harm to have upsized wire from the mimimum required. You can use the 30 amp breaker though I would install a 20 or 25 amp double pole rather than the maximum allowed. You can most likely exceed the 67 feet since you are using 10awg. Verify you have 10 awg before extending past the 67 feet you mention!
I'm not sure what the 30 amps you mention in your post is can you tell us where that comes from? I dont believe it is a specification that would be related to the electrical requirements of your welder.
The use of a 6-50 connector is typical of most 220 volt to 240 volt rated welders with output ratings similar to this millermatic 175.

Your owners manual will give you the exact requirements for the breaker/size or fuse/size and the minimum conductor size. So I would purchase the welder then after reviewing the manual compare it to the above, it should be along the same specifications, that is.... minimum 14 awg, 20 or 25 amp double pole breaker or fuse. Then decide if you can convert the dryer outlet which should be 30 amp and 10 awg if electric 220 volt dryer.

Do not try to make foolish and dangerous modifications to try to make something work.
 

Last edited by Roger; 09-29-05 at 10:32 AM.
  #6  
Old 09-29-05, 03:07 PM
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This welder does not need a 50A circuit and will work very well from a 30A dryer receptacle. The NEMA 6-50P is used on that welder because it is a very typical welder plug, rated UP TO 50A.

You can certainly make an extension cord with 10 AWG SO cord (or even 12 AWG because of the machine's duty cycle), and you only need the two hots and the ground. The MM175 has a duty cycle of 30% at rated output of 130A, even less at maximum output of 175A.

Oftentimes, you can buy the plugs from HD and you make them yourself, so you won't even need to put in the neutral prong, just the two hots and the ground on a 4-wire dryer plug. You put a NEMA 6-50R (female) on the other end of the cord for your welder to plug in.

This is a common question on the welding boards.

Ground conductors are for fault currents; neutrals are for purposely carrying return and unbalanced currents. They are to be bonded only at the main service panel.
 
  #7  
Old 09-29-05, 11:58 PM
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Thanks for all the reply

The is from the owner manual

ELECTRIC SERVICE GUIDE FOR 230 VAC MODEL
INPUT VOLTAGE-----230
INPUT AMPERES AT RATED OUTPUT-----20
MAX RECOMMENDED STANDARD FUSE RATING IN AMPERES
-----TIME DELAY-----25
-----NORMAL OPERATING-----30
MIN INPUT CONDUCTOR SIZE IN AGW-----14
MIN INPUT CONDUCTOR LENGTH IN FEET (METERS)-----67(20)
MIN GROUNDING CONDUCTOR SIZE IN AGW-----14

Label on my cable

Carol 10/3 90c (ul) Water resistant S00w csa (-40c) FT-2 P-7k-123033 MSHA Make in USA 600v
Cable is over 1/2 in in diameter with the insulation, three individual stranded wire, white,black,green.

Both the plug (NEMA 14-30P 4 prong)and receptacle (NEMA 6-50R)are from lowes and rated at 50 amps.

My sub-breaker box in the house has a double pole 30 amps for the dryer outlet.

Reason why I do this and get it so complicated is ,instead of just change out the plug on my welder and make it work which I gain nothing, I just make a gender change extension cable, so now I can drag my welder all the way to the end of the drive-way. BTW I get the 10/3 cable free from the refinery, only have to pay for both the plug and receptacle.
 

Last edited by CBR900RR; 10-01-05 at 11:09 PM.
  #8  
Old 09-30-05, 09:57 AM
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Originally Posted by CBR900RR
I just make a gender change extension cable, so now I can drag my welder all the way to the end of the drive-way. BTW I get the 10/3 cable free from the refinery, only have to pay for both the plug and receptable.
I did the same thing for two years with a MM175. As payment for my services, I'll take all the free 10/3 cable you can send me!!
 
  #9  
Old 09-30-05, 10:02 AM
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You need to change the existing breaker to a 25 amp inverse time breaker, same as in you get at the home centers. This is the maximum as stated by the manufacturer. I do not agree to adapting an extension cord with 6-50R to fit the welder at one end and a 14-30P on the other end to fit the dryer outlet. Either this should be a dryer circuit or a welder circuit. Might work but I believe this is unecessary confusion and not according to the manufacturers intent or instructions. I also dont see where you saved anything other than not replacing the dryer receptacle. My advice is to change the breaker, it is over the max reccommended by the manufactuerer and change out the dryer receptacle to a 6-50R and your extension cord should have a 6-50P on the end where you have the 14-30P. Good Luck
 
  #10  
Old 09-30-05, 09:20 PM
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Originally Posted by Roger
You need to change the existing breaker to a 25 amp inverse time breaker, same as in you get at the home centers. This is the maximum as stated by the manufacturer. I do not agree to adapting an extension cord with 6-50R to fit the welder at one end and a 14-30P on the other end to fit the dryer outlet. Either this should be a dryer circuit or a welder circuit. Might work but I believe this is unecessary confusion and not according to the manufacturers intent or instructions. I also dont see where you saved anything other than not replacing the dryer receptacle. My advice is to change the breaker, it is over the max reccommended by the manufactuerer and change out the dryer receptacle to a 6-50R and your extension cord should have a 6-50P on the end where you have the 14-30P. Good Luck
For the breaker, I think it listed that I have 2 choice, 25 amps time delay or 30 amps normal breaker? The manual also list "AMPERES INPUT AT RATED LOAD OUTPUT 230V, 60Hz,SINGLE PHASE 19.5", So I believe continues draw at rated output is 19.5amps, initial start will be close to 25amps, ?just guessing?

If I change out the dryer to 6-50, how do I hook up the netural on the dryer?

As for the saving part, I did spend more to accomplish an extension cord, verus replace the the dryer plug, dryer outlet to 6-50, all I did was to make it fit and nothing more. Also I don't want to tamper the dryer or the dryer outlet, the house is only 2 years old.

I am not trying to argue with you guys(BTW you guys have allot more knowage than I do), I know I violate the code( I have the black ,and white-netural-wire on 110v and green on ground), but as long as it is save to do, I don't see why not.

Thanks for all who post.
 
  #11  
Old 09-30-05, 10:42 PM
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Originally Posted by CBR900RR
I have the black ,and white-netural-wire on 110v and green on ground)
This is a 230/240V welding machine. The white wire (this is the SO cord, right?) should be taped as a 2nd black or as a red and landed to the other hot leg, or did I misunderstand what you are saying?

This installation is very typical for 30A welders in home shops.
 
  #12  
Old 09-30-05, 11:30 PM
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yep, black on 110, white on 110 ad green on grd.
 
  #13  
Old 10-01-05, 01:06 AM
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The NEC prohibits constructing a cord in this manner, you cannot make a cord with a 30 amp 4 wire plug and a 50 amp 3 wire receptacle, see section 406.7.

The welder and dryer have different requirements and require different circuits.

The purpose of the NEC is to provide a minimum safety standard, to give advice that disregards this standard is irresponsible.
 
  #14  
Old 10-01-05, 08:04 AM
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406.7 Noninterchangeability.
Receptacles, cord connectors, and attachment plugs shall be constructed so that receptacle or cord connectors do not accept an attachment plug with a different voltage or current rating from that for which the device is intended. However, a 20-ampere T-slot receptacle or cord connector shall be permitted to accept a 15-ampere attachment plug of the same voltage rating. Non–grounding-type receptacles and connectors shall not accept grounding-type attachment plugs. (2002 May Meeting Edition)

I disagree with your interpretation. Though I am no kind of authority, nor am I an expert in residential construction, I read this as making a RECEPTACLE that is able to accept a wrong-current plug, not as saying that it is wrong to make an adapter cable for a specific machine, which is a common practice in these situations. He is doing nothing unsafe or irresponsible or uncommon. The machine draws 20A and has its own internal overload protection, as it is designed to operate from UP TO a 50A receptacle. He is not altering the dryer's receptacle or wiring and there is no need to alter the circuit protection accordingly. Would you also consider it wrong to cut off a factory-installed 50A plug and replace it with a 30A plug? Without knowing anything about the machine, that might seem ludicrous at first...
 
  #15  
Old 10-01-05, 09:14 PM
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Sorry, may be I did not discribe my situation good enough.

I have a 2 years old house ,built from 2003, it has 200amps service upgrade, 100 amps going inside the house into the sub-breaker box ,and 100amps for outside use, and on the inside sub-box have a double pole 30 amps 220v breaker for my dryer outlet in the garage, the outlet is a NEMA 14-30R 4 prong, and the welder is a NEMA 6-50P 3 prong, welder draw 19.5 amps and ~25amps at initial start-up, and it call for a 30amps breaker by the manufacture.

I construct an extension cord with a --50amps NEMA 6-50P plug--30 amps 10/3 cable--50 amps NEMA 14-30R receptable.


With the above setup, everything is above the 25 amps requirement.

Only one thing that is in question is the gender change from NEMA 6-50P plug to NEMA 14-30R receptacle.
 

Last edited by CBR900RR; 10-01-05 at 11:10 PM.
  #16  
Old 10-01-05, 09:24 PM
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Originally Posted by CBR900RR
I construct an extension cord with a --50amps NEMA 6-50P plug--30 amps 10/3 cable--50 amps NEMA 14-30R receptable.

With the above setup, everything is above the 25 amps requirement.

Only one thing that is in question is the gender change from NEMA 6-50P plug to NEMA 14-30R receptable.
We need to clarify some terminology. The PLUG is the male end with the prongs. The RECEPTACLE is the female end with the holes. This applies whether it's in the wall or on the end of a cord.

So you want a male NEMA 14-30P on one end of the cord to plug into the NEMA 14-30R in the wall. As you can see, "P" stands for PLUG, and "R" is RECEPTACLE. You won't use the neutral's prong, just the two hots, plus the ground.

Then, you need a NEMA 6-50R on the other end of the cord to plug in the welder's NEMA 6-50P.

Dang, you should be welding by now... But, seriously, take your time, make sure you understand exactly what needs to be done and why, and that you do it carefully, following the stripping directions that come with the cord caps so that there are no bare wires running stray inside the cord caps and the strain relief on the cord cap appropriately tightens onto the JACKET of the cord, not onto the insulation of the wires inside.
 
  #17  
Old 10-01-05, 09:52 PM
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Yep, that how I make the cord(gender change plus extension).

Machine should be here on Monday, I order it thru ebay. I already read thru the on-line owner's manual, get my shield gas, make my extension cord and have the cart ready for the machine, plus collect some pratice metal bar.

Also I have check with a muti-meter and is wire correctly.
 
  #18  
Old 10-01-05, 10:38 PM
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Originally Posted by MAC702
I read this as making a RECEPTACLE that is able to accept a wrong-current plug, ...
“making a RECEPTACLE” ?? Do you make receptacles?
Section 406.2 requires receptacles to be listed and marked with the manufacturer's identification. That pretty much prohibits any homemade receptacles.

Section 406.7 covers receptacles AND cord connectors and plugs. It says receptacles, cord connectors and plugs cannot be constructed in a manner that would make a device interchangeable with one that is different. That is exactly what constructing a cord like this is doing. It is PROHIBITED.
 
  #19  
Old 10-02-05, 08:19 AM
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406.7 Noninterchangeability.
Receptacles, cord connectors, and attachment plugs shall be constructed so that receptacle or cord connectors do not accept an attachment plug with a different voltage or current rating from that for which the device is intended. (relevent part)

This Code is obviously applying to SOMEBODY who is 'constructing receptacles, cord connectors, and attachment plugs....' I respect your opinion, but it does NOT mention end-users with specific equipment making adapter cords, which are industry-common. "Constructing" a 50A plug in such a way (perhaps by modifying prongs, etc) so that it will directly plug into a 30A receptacle would be in clear violation. I would say the Code could be clearer on this point, as it has certainly allowed us to disagree, and I do so respectfully. Does anyone have a copy of the Code HANDBOOK handy? I wonder if it might clarify this issue. All I brought to Colombia is my computer version of May 2002.

Aside from your interpretation of the Code, what do you find UNSAFE about this?

Also, I ask again, would you cut off a factory-installed (on a LISTED machine) 50A plug and replace it with a 30A?
 

Last edited by MAC702; 10-02-05 at 08:32 AM.
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