welding lead loss

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any rules of thumb for loss over distance? am working with some fitters who are gonna need 400 foot of weldlead..if they want 75 amps at the stinger, what setting would you start with back at the truck(ranger).?
Reply:Trouble is it's voltage you lose. The resistance in the wire will limit the maximum curent, but it will change the voltage you have for the arc. I would guess you will loose about 1/4 of you arc voltage with 3/0 wire.Here is a calculator that might help.http://www.csgnetwork.com/voltagedropcalc.html 24 volt dc or 1single phase AC should be close.Lincoln PT185 TIGLincoln 175 MIGLincoln 240 amp AC StickLind Needle Arc plasma welderPlasma cutter, soon???
Reply:I've had over 850' of lead on a Lincoln Classic II, the welding was fairly light duty with 1/8" lohi, intermittant.I initially set the machine a bit hotter than normal to compensate, but had to call up on the radio and have them put it about where I normally ran that rod.This was with all good lead and solid connections.JTMcC.
Reply:Multiple problems there.As stated, because of resistance losses over the distance of wire, the voltage at the end drops.And also because of resistance losses over the distance of wire, the wire heats up.General rule-of-thumb for wires is to keep voltage losses below 5-10%.  Which means that for 400 feet (one way) of wire and 75 amps flowing, you need 700kcmil copper wire to keep the voltage loss around 5% for 24V at the machine and that would give you 22.9V at the stinger.Last edited by MoonRise; 09-19-2008 at 03:30 PM.  The best laid schemes ... Gang oft agley ...
Reply:700 is heavier than "standard" welding lead?
Reply:That's 7 'sizes' up from 4/0 wire.  It's B-I-G.4/0 copper wire has a cross sectional area (circular mil area) of 211,600.  For 400 ft one-way at 24V and 75A, the 4/0 wire will drop 17% or 3.66V (out of the starting 24V) and you end up with 20.34V at the stinger.The 700 kcmil copper wire has a cross sectional area of 700,000, over 3x as big around as the 4/0 (which is pretty big to begin with).  At 24V to start with and 75A, over 400 ft one-way you will end up with 22.89V at the stinger (a loss of 1.11V).  The best laid schemes ... Gang oft agley ...
Reply:All theory aside, there are billions upon billions of welds made every year in thei country using 400' or more using regular welding lead.We wouldn't have a powerhouse in this country if it weren't for banks of 8 packs hundreds of yards away from where the welds are actually made.Or a car plant, ect, ect.You can spend half a shift tracing your leads thru several decks, over hill and dale, and by the time you find the machine you are welding off of, turn it up, and return to your work area, someone has done stole it and you have to find another one to use.Don't wory about 400 of leads, it'll work just fine.JTMcC.
Reply:it  sounds like a lot of copper to save 2.5 volts.. i must be missing something  as to what  wouldnt work if  they used 400 feet of 4/0...we are looking at  fairly light welding- 3/32 7018 at 75 - 80  amps..3" sch 80 pipe with socket weld fittings.not  burning too much rod..some hanges, some  fitting and then a bit of arc time..
Reply:2.5 volts doesn't sound like much.Except that it's 10% of your starting 24 volts.And 10% is usually noticable.Run 4/0 and accept and compensate for the losses.  The best laid schemes ... Gang oft agley ...
Reply:I've stumbled across these charts types of charts before. One of these days I'll actually save a link.  Stick Welding 'output' leads are a slightly different creature as compared to input/supply leads. Any input/supply, AC or DC can be critical as mentioned. More so for some things than others. But with SMAW there is this whole volt-amp curve thing going inside the arc that I really don't understand other than you can be a little more stingy with the copper and much of what the final result is lies in the hands of the operator. More of a total wattage thing. This chart shows the recommended sizes based on low loss, staying within normal rod parameters and certain safety factors. Then if you decide to push the limits a bit, well with larger superflex cables, a bit can amount to quite a few feet. http://store.weldingdepot.com/pdf/weldingcable.pdf
Reply:Remember that your SMAW machine tries to be a constant CURRENT device, whereas your house electrical supply is a constant VOLTAGE source.  The machine can compensate (at a voltage loss to be sure) to SOME degree to maintain the current you want at the other end.  It's certainly not an IDEAL machine, but it will try; usually to the extent that you can weld a lot further away with just 4/0 that you probably think you can; as JTMcC has already stated.It will probably be more of an issue if you were running a remote wirefeeder on a CV process.
Reply:75 amps in 4/0 in NEVER going to get hot.  Sure there will be a voltage drop, so kick up the machine a little.  You can compensate with the machine for the voltage drop, but not if the cables heat up.  ONLY 75 amps.....DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:much thanks to all for their h elp
Reply:It's not so much the heating up of the cables, although that does occur and is something to be considered.It's mostly the voltage drop over 400 feet of cable out and another 400 feet of cable back.Yes, it's 'only' 75 amps that he wants to (or needs to) use.  Thank goodness for that low amperage.  But he's only starting with 25-30 volts to begin with, and over that 800 feet of cable with only that 'low' voltage pushing it the voltage drop is a noticable percentage of the 'starting' voltage.And when you ask/tell the machine to give you xxx volts or amps, it doesn't know or care (to the machine) if that power is going to the actual arc or if it is getting lost in cable resistance.And notice in the nice chart that Sandy posted the PDF link for that the distances in the chart are TOTAL distance (there and back).  So 400 feet away from the machine to the stinger is 800 feet of cable (400 feet for the stinger and 400 feet for the work/ground lead).For less than 5% loss in the cable, even at 'only' 75 amps, you need 700 kcmil cable for 800 feet of total cable.Run 4/0 over the 800 feet of cable at 75 amps and you have 17% loss in the cable.  If you can accept and compensate for the loss, run the 4/0 and deal with it.  The best laid schemes ... Gang oft agley ...
Reply:How about this, get 220 volt inverter, run 400' of # 10.....In the owners manual for my V155-S, it says I can run 200' of #12 wire.  I made an adapter and just use 12 gauge extension cords.  I have used up to 125 feet.  Its 100% duty cycle at 100 amps.Cost a lot less than all that 4/0.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:David,I was thinking along the same lines.Remember, if the work is 400 feet away from the machine then you need 400 feet of (heavy) cable from the machine to the work AND another 400 feet of (heavy) cable from the work back to the machine.Is there any way to get the work and (a) machine closer together?  A generator or a loooong extension cord and then a small efficient stick machine like one of the new(er) inverter machines?  Or a no-electricity-needed gas torch?Even if you had to go out and buy those things, I think it would cost less than 800 feet of 4/0 welding cable.  Unless you really have a need for 800 feet of 4/0 welding cable for other things as well.  The best laid schemes ... Gang oft agley ...
Reply:Use the welding chart Sandy gave you. I worked at a papermill and saw some really long runs with 1/0 wire, which is where the chart says you need to be.  If you used anything much bigger than 4/0 it would take a mule team to pull it 400 feet.
Reply:Originally Posted by 6010...If you used anything much bigger than 4/0 it would take a mule team to pull it 400 feet.
Reply:Question 1:  If you are working on a large steel structure  with beams for floors and steel support posts everywhere too, if you attached the ground to the steel near the machine but ran the stinger lead 250 feet to where you're working, would the voltage drop in the ground circuit be more or less than using  a 250 foot ground lead. The resistance of steel is poor, but there is so much more  of it; would the extra mass/large path compensate for the higher resistance? Any extra hazards involved, assuming the leads are all good?Question 2: How else does the photo above figure into welding? (This should be an easy one. No, nothing to do with politics).
Reply:we are working under security conditions and cannot take  electrical power from the facility. must use gas engine welder. actually planning to connect work lead to the pipe we are working on 300 feet from point of welding;using  the pipe for the circuit. probably grind off 20 coats of  paint and if there's any steel weld a lug to it and connect there.structure is concrete. i think the contractor has lots of 50 foot sections of lead .oldiron2--the mule turds look like my welds?
Reply:I think I can help you with the first question. If your ground lead on your welder is as long as the wire going to the stinger then it  would be much better to ground close to where you are welding, since the current return path would be through the steel and then through ground lead. So it would be better to ground as close to the weld as possible. But there is another reason, being an old instrument man, that I would advise such a hook up, close to the weld I am talking about. If there are instruments in the piping system, you want to ground as close to the weld as possible to keep any welding current out of the instruments.As to the second question I haven't got a clue. This could be for two reasons. My age may keep me from understanding, because I am old and out of touch. Or it could be because I have downed about 14 Coors and my comprehension is a little off.Last edited by 6010; 09-21-2008 at 06:28 PM.
Reply:I was just thinking about a new steel structure such as an office building; this is just a hypothetical situation. Just wondering about voltage loss through the steel compared to the copper lead cable. Not concerned with arc blow,  other welders, etc.I won't give the answer to (2) yet.....Think OA  brazing or cast iron welding...
Reply:Originally Posted by Oldiron2I was just thinking about a new steel structure such as an office building; this is just a hypothetical situation. Just wondering about voltage loss through the steel compared to the copper lead cable. Not concerned with arc blow,  other welders, etc.
Reply:I ground at the base of a steel cell tower.  There is no way I am taking the ground up with me.  Never had a problem or noticed a drop in voltage or any kind of welding performance.  I have only done this as far as 150' .I have not tried the V155-S on a cell tower yet.  All I would have to take up is the power supply cord, ground will be near the work.DavidLast edited by David R; 09-22-2008 at 06:37 AM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:ground at the base of a steel cell tower. There is no way I am taking the ground up with me. Never had a problem or noticed a drop in voltage or any kind of welding performance. I have only done this as far as 150'Originally Posted by Oldiron2 ... Question 2: How else does the photo above figure into welding? (This should be an easy one. No, nothing to do with politics).
Reply:Borax is used as a (or part of the) flux for welding and brazing.400 feet of #10 AWG extension cord at ~$100 per 100 ft, a couple of voltage plug/receptacle adapters at $10-$20 each, and then a small efficient stick inverter welder at the end of the extension cords.  Supply power from the engine drive machine, plug in the appropriate adapters and then the 4x100 ft extension cords, and then the inverter welder at the end by the work.  Weld and be done with it.Or haul 400 ft (x2) of 4/0 welding lead around.  Using the 300 ft of pipe as the current return path is maybe possible, but you have to check exactly HOW that 300 ft of pipe is connected and verify electrical continuity and resistance and what else is going on with/on/to that pipe before trying to use it to conduct 75+ amps over its length.  If the pipe is threaded together, you may weld the pipe together if you use it as welding current return.  If there are pipe unions in the path, you may not have -any- electrical continuity.  If there are devices/instruments using the pipe as ground or whatever, you may fry them (and then have to replace them if the wokplace blames you for the instrument failure).  Etc, etc, etc.Oh, and the conductivity of steel is more like 25% that of copper, not even including any possible joints or corrosion in any possible joints, etc.  Aluminum's conductivity for 'common' aluminum alloys is around 30-40% that of copper (42% conductivity for 4043 compared to copper, and 29% for 5356 compared to copper.  Pure (or nearly pure) aluminum has a conductivity of around 60% that of copper.  The best laid schemes ... Gang oft agley ...
Reply:well/ they brought 400 feet of 2/0, did not have problem with machine set at 90 amps, fitter felt he was getting good penetration with 3/32 6010/7018.  we walked the "work circuit" all threaded 3" pipe, somehow got an arc at the work after we ground off the paint and used a magnet to connect.i have learned a lot from  these responses, thanks guys.
Reply:MoonRise has the correct answer above.
Reply:Originally Posted by 6010 ...When I first started working at the paper mill I could go up to the top taking 2 steps at a time with no rest stops.... 16 years later, when I retired, I had to take 2 or three rest stops on the way up.
Reply:ive been walking around jobsites for35 years..high rise, sewage treatment,clean rooms,structural,mechanical..cant remember hardly ever seeing a work clamp near the weld, or ever get moved for that matter..typically welders get wired in and stay put, and "grounded" to the structure for the work lead..and the lead that feeds the stinger goes all over the place..not saying its right but thats what happens..of course thats during new  construction when no instrumentation is installed yet..not for modifications to a working system,..
Reply:Originally Posted by denrepLet's see - Maybe by the time team and teamster crawled out of Death Valley, they felt hotter than flux?
Reply:I have run 7018 and 6010 both through 1000ft of 4/0 off of an 8 bank while doing powerplant construction. I had no problems and all of the welds passed x-ray. Took all day finding enough lead and getting it strung, but there was no other option. Electrodes are designed to work in a voltage range, not a specific.The difference between art and craft is the quality of the workmanship. I am an artist.