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Solutions Needed Please (Running 40 Amps on 20 Amp Circuit)

Solutions Needed Please (Running 40 Amps on 20 Amp Circuit)

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  #1  
Old 08-26-06, 06:50 AM
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Solutions Needed Please (Running 40 Amps on 20 Amp Circuit)

Hi all, I am wondering about a stoopid solution I have to getting power to a welder in my outer shop area 125 feet from the house...... the welder is a hobby welder 110 volts 40 amps I think. It uses 1/16 size rod, short use 1/4 to 1/2 inch long bead at a time. Now for the question, if I string two 100 foot extension cords 16 gage in parallel and cut a 50 footer and wire it to the ends of the 100 footers that would make the 125 foot length, the wiring would be no problem for me but I am wondering if the voltage drop would be enough to actually run the welder and if so, would I have a hot wire fire line between the house and the welder??? this would only be a temporary use application untill I can afford the big bucks for the " right way" .... so can it work or am I asking for a lot of problems??? thanks for your tolerance. Brian...
 
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  #2  
Old 08-26-06, 07:16 AM
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check that name plate again, or post the configuration on the end of the cord. 40 amps is kinda odd for a 120 volt circuit.

On the cord cap you may see the name nema followed by some letters and numbers. that would be the nema configuration of the cord.

Or check this web site and see if you can find the configuration there. http://www.elec-toolbox.com/usefulinfo/nema1.htm
 
  #3  
Old 08-26-06, 07:35 AM
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amperage

hello, well I did find the manual and actually looked at it he he .
input power 115/230 ( currently wired for 115V)
Max Amp output: 120 Amps
Amperage Draw: 42 Amps

It is a little hobby welder from Harbor Freight, Chicago Electric brand, I had to supply the plug to wire it up for 115 so I have no numbers there..........

I have all the extension cords allready, 16 gague tho. do you think it would reasonably work as a temporary use??? thanks for any input Brian...
 
  #4  
Old 08-26-06, 07:48 AM
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I bet it was fun finding a breaker. Just curious why you did not choose to wire it 230 volt. You could cut the needed wire size down.

For 42 amps you need at least a number 8 wire that is before any voltage drop. If you change to 230 volt you would need at least a number 10 wire.

If you allow for voltage drop at the 120 volt setting you will need to go up to number 6. If you change to the 230 volt setting you will not need to upsize the wire.

To answer your original question. I do not think that it is a good idea from the start. lol.. but even then two number 16 is no where near the required size of a number 6.
 
  #5  
Old 08-26-06, 08:07 AM
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Breakers and such.......

thanks for the inputs... Right now I am running it off of a outlet I wired from the backdoor porch light through the wall,, covered by a 20 amp breaker, it tripps if I try to weld the full length of the electrode, so I only make short welds... I have had my main circuit breaker panel changed out from an old Stablok brand to a square d ( gawd do not get me started on StabLok) I had a subpanel mounted outside the wall wired for future use of 220 V and as yet havent the funding ( LOL ) to accomodate the required wiring run out to the shed from the far side of the house........... so I have been welding out on the back patio,,, well....... the ole lady has so far been accomodating untill I melted the back sliding door with shards from the grinder... the dog house has so far been comfortable but.............. so just out of curosity, how many runs of 16 gague would equal #6 or # 10..... the doghouse does have fleas......... Brian...
 
  #6  
Old 08-26-06, 08:13 AM
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STOP RIGHT NOW RUNNING A 40 AMP DEVICE ON A 20 AMP CIRCUIT BEFORE YOU, YOUR WIFE AND YOUR DOG DIE IN A FIRE.

This repeated misuse of that circuit WILL cause damage to the circuit.

It is not a good idea to parallel extension cords. If you must, make a cord of the proper guage wire, and use cord ends with the proper nema configuration so that the welder cannot be plugged into a recepticle of the wrong rating.
 
  #7  
Old 08-26-06, 08:25 AM
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Thanks.

I guess I had that comming..... I DO appreciate your knowledge.. I didn't realize what I was doing to the house wiring.. and I will not persue the parallel idea, fires arent a good thing...... ( I did have the feeling it was not a good idea) well its probably for the best to quit welding from there and wait for the proper wiring to the shed......... that will most certainly get me out of the doghouse....... Thank You, I really do appreciate your inputs... Brian...
 
  #8  
Old 08-26-06, 09:23 AM
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You could look arround for a used generator. you need about 5000 watts. I got a 5550 at the big box store for under 600 dollars. You could then rewire the welder to 230 v and be all set to go.
 
  #9  
Old 08-26-06, 10:48 AM
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generator

that is an idea, but I have to eventually supply the shed with buried wire service as well.... in the long run wire would probably be better, just have to wait for it......... thanks for the suggestions and info Brian...
 
  #10  
Old 09-16-06, 12:32 PM
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dog

Originally Posted by nightwalker
thanks for the inputs... Right now I am running it off of a outlet I wired from the backdoor porch light through the wall,, covered by a 20 amp breaker, it tripps if I try to weld the full length of the electrode, so I only make short welds... I have had my main circuit breaker panel changed out from an old Stablok brand to a square d ( gawd do not get me started on StabLok) I had a subpanel mounted outside the wall wired for future use of 220 V and as yet havent the funding ( LOL ) to accomodate the required wiring run out to the shed from the far side of the house........... so I have been welding out on the back patio,,, well....... the ole lady has so far been accomodating untill I melted the back sliding door with shards from the grinder... the dog house has so far been comfortable but.............. so just out of curosity, how many runs of 16 gague would equal #6 or # 10..... the doghouse does have fleas......... Brian...
i hope the dog has been some where else while your welding ? nbr 10 wire handles 30 amps nbr 8 handles 40 amps 125 ft is a long ways to go. I suggest if your going to do much welding that you step up to a used miller mig welder & get rid of the thing your using
 
  #11  
Old 09-17-06, 07:10 AM
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Red face

As Jwhite said, what you're doing now is not safe and something will ultimately fail, and may start a fire, maybe in the wall of your house, or someone will get electrocuted.

Since as you say, you've already got a 240V panel on the outside of your house, this is what I would do if it was my shop.
It's only my opinion, and I'm not responsible for your installation or the safety of you or others. You be the judge. If you can't do the work safely, get someone who can to do it.
Electricity can kill! Quick!

I would go to The big Orange store or the Big blue one that's usually next door and buy enough (150'?) of #2 aluminun mobile home feeder. It's 4 conductor wire (2 hots, 1 neutral and 1 ground) and good for 100 amps when used as a feeder. It's rated USE/RHH/RHW. If I could trench 24" deep from the house to the shop I would bury it directly in the earth without conduit. If I could only get 18", I would put it in 1 1/4" PVC conduit or cover it with 2" of concrete under the dirt. If I could only get 6" I would put it in rigid or IMC steel conduit. I would feed it with a 100 amp breaker from my backporch panel. I would make sure that the backporch panel has capacity to supply 100 amps, if not then I would use as large a breaker as it could safely feed (up to 100 A max.). In the shop I would install a 100 amp 12 space main breaker panel and install a 50A breaker to supply my welder receptacle. I would then have extra power and breaker space for lights and other loads. I would drive a (5/8" diameter x 8') ground rod at the shop and bond it (to the shop panel grounding bar, panel enclosure and the green grounding conductor run with the supply cable) with a #6 copper conductor. I would keep the neutral (white) wires seperated from the ground and isolated from the ground rod and panel enclosure.
My estimated material cost would be:
Wire 150' #2 aluminum cable @ 1.85/ft............$270
100 amp 2 pole breaker =...............................$40
125' 1 1/4" sch 40. pvc conduit @ $.050/ft. =....$62.50
100 amp 12 space main breaker panel =.............$60
50 amp 2 pole breaker =.................................$10
50 amp welder receptacle...............................$15
Misc PVC fittings and glue =............................$30
Ground rod, 10' wire and clamp =.......................$2
Total estimated material.............................$489.50
 
  #12  
Old 09-17-06, 10:31 AM
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Originally Posted by mrputz1
...nbr 10 wire handles 30 amps nbr 8 handles 40 amps 125 ft is a long ways to go.
What is the duty cycle of this welder? I'm betting it's between 10 and 20%, which means you can take its input amperage and multiply it by 0.45 to find the needed ampacity of the input conductors.

While this is not often done in residential settings and there are other considerations (labeling, etc.) that should be taken into account before doing so, it at least helps to show that smaller wire is not as dangerous as you first might think.
 
  #13  
Old 09-17-06, 10:36 AM
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Mac, Are you saying that the nameplate data from the welder. which is 42 amps, does not take into account the duty cycle of the welder?
 
  #14  
Old 09-17-06, 12:33 PM
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Originally Posted by jwhite
Mac, Are you saying that the nameplate data from the welder. which is 42 amps, does not take into account the duty cycle of the welder?
That is correct. The duty cycle will be listed somewhere else on the nameplate, as well as the "rated" output amperage used to calculate that duty cycle.
 
  #15  
Old 09-17-06, 12:43 PM
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For example, take a very popular welder class, like the Millermatic 135. It has a maximum output of 135A, but has a "rated output" of 90A. At its rated output, it's duty cycle is only 20%. It's even less at its maximum output. Its input amperage at its rated output is 20A. While it needs to be on a 20A dedicated circuit for best results, it can also safely be run with #14 wire, as long as nothing else gets used on that receptacle. This is a hard example to justify, because of little savings and the ease at which it can be misused, but you get the idea.

Another example would be the very popular Lincoln Electric AC225 Stick welders, commonly called "Tombstones." These things are found almost anywhere and have been mainstays for several decades. They, too, have a 20% duty cycle when they are drawing close to 50A. This is why they have been used on #10 wire in many, many installations. Here, the savings are much more pronounced and since they were dedicated welder receptacles (NEMA 6-50R, usually) there was little chance of other things being plugged into the circuit.
 
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