HOW DOES AC WELDING DIFFER FROM DC WELDING

[Shield Arc]

Shield Arc: For the n00bs out here, tell me why DC is safer in that circumstance than AC?

Lets see it rains here about 160-days a year, for an average rain fall of 40-inches per year. When welding in the pouring down rain with a DC welder, and you get shocked it is just aggravating. I would guess, (only guessing because I've never done it) welding in the pouring down rain with an AC welder just might ruin your day!:shocked:

 

[LD1]

Wonder if you could talk these guys into using an AC welder?

I dont see the issue?? They arent in the water or anything:laughing:

As far as ruining your day, not quite. Before we replaced the ground lead on out buzz box, it had a bare spot in it. Every once in awhile, while kneeling down and welding, I would have my knee on the bare cable. That coupled with an arm resting on the work peice:shocked:

Its a tad more bite than DC, but aint terrible cause its still low voltage.

 

[joshuabardwell]

Lets see it rains here about 160-days a year, for an average rain fall of 40-inches per year. When welding in the pouring down rain with a DC welder, and you get shocked it is just aggravating. I would guess, (only guessing because I've never done it) welding in the pouring down rain with an AC welder just might ruin your day!:shocked:

I'm afraid that I still don't understand. Is it just that AC is more dangerous than DC?

 

[Shield Arc]

Wonder what would happen if you were soaking wet?

 

[LD1]

Wonder what would happen if you were soaking wet?

I dont know. I never tried it.

But I am afraid that I probabally wouldnt want to try DC welding soaking wet with poor leads either

 

[Shield Arc]

I probabally wouldnt want to try DC welding soaking wet with poor leads either

Been there, done that, even got the T-shirt.:laughing:

 

[k0ua]

let me try to answer that I found this on a welding forum and I believe it to be true

Assuming you are creating a good ground (damp feet, wet soil, standing in water, etc.), you can get shocked equally well with either AC or DC. The difference is, AC has the ability to freeze up your muscles, working with DC you go "Ow", and drop whatever hurts. AC you have the very real possiblility of freezing up, and hanging onto the stinger, ground, or whatever.

 

[Shield Arc]

I didn't see it, but I was on the job not to far away when it happened. At the time there was so much work around here, you couldn't get enough weldors, or welding machines. We were building a big cofferdam with tie backs. The company rented a small engine drive I don't remember what it was, because I didn't want any part of it, I had a brand new Lincoln SAE-400, and no body was getting that thing away from me! Anyway this new hire came out to work, forgot his rain gear at home. In no time at all he was soaking wet. He and another guy had to roll his little welder to another location through the mud, the new hire rolled up his leads on the handle bars, and grabbed both handle. Well I guess the fool grabbed the stinger and ground clamp one in each hand. The guy helping him couldn't hardly stand up straight when telling us the story later! I guess the weldor went to his knees convulsing! Scared the helper! At first he couldn't figure out what was happening! Then he seen the guy was holding the stinger, and ground clamp. The helper reached around and shut the welder off. The weldor was so shaken up he had to go home!

 

[Soundguy]

i have a buddy that does underwater salvage. they use stick welders dc, reverse polarity.

 

[Shield Arc]

i have a buddy that does underwater salvage. they use stick welders dc, reverse polarity.

He also has someone top side who controls a knife switch who only gives power when told to.

 

[Soundguy]

cutting torch work too.


He's told me some neat stories. he gets to do fun stuff.

tanker hull inspections.. open see diving.. salvage and recovery... worked off the coast of texas a while before moving back here to fl...

 

[Shield Arc]

I've worked with lots of divers over the years, on one project I had 8-divers and tenders working for me. We had 2-decompression chambers on board. Deepest dive was 215-feet. But they were on gas, at that depth. Spent most of their day staging up and down. Then hours in the chamber. 3 of the divers had worked in the north sea. Yep great stories they have!

 

[BIG DOOLEY]

Nice brother in law.
If you buy yourself a tig torch set and lease an argon tank you can start learning how to tig weld also.(carbon and stainless)
You won't have the best arc and heat control but you will have fun.
you may never want to stick weld again.
I have several mig welders, stick and tig.
Just me, I prefer to tig most of the time.
Congrads on your new welder.
You need to buy your brother in law a beer.
Tom

 

[oldpilgrim]

I didn't see it, but I was on the job not to far away when it happened. At the time there was so much work around here, you couldn't get enough weldors, or welding machines. We were building a big cofferdam with tie backs. The company rented a small engine drive I don't remember what it was, because I didn't want any part of it, I had a brand new Lincoln SAE-400, and no body was getting that thing away from me! Anyway this new hire came out to work, forgot his rain gear at home. In no time at all he was soaking wet. He and another guy had to roll his little welder to another location through the mud, the new hire rolled up his leads on the handle bars, and grabbed both handle. Well I guess the fool grabbed the stinger and ground clamp one in each hand. The guy helping him couldn't hardly stand up straight when telling us the story later! I guess the weldor went to his knees convulsing! Scared the helper! At first he couldn't figure out what was happening! Then he seen the guy was holding the stinger, and ground clamp. The helper reached around and shut the welder off. The weldor was so shaken up he had to go home!

I was welding at 125 amp Ac, and it was an awful hot humid day. I had to change the ground cLamp positions and left the welder running while I did it. One very sweaty hand on the ground clamp and the rod holder in the other very sweaty hand. There is a hole in the grip of the handle where you can access the set screw that attaches the cable and the handle was also soaking wet with sweat.

I could feel the current going in one hand, across my chest to the other hand. Everything went dark, I shook violently, it melted my wedding ring, burned my fingers, and caused a spasm in my finger muscles that dislocated a finger. I could not move, let out a loud "aaaaaaaàhhhhhhhhhh", my wife heard me,ran into the garage and flipped off the breaker but not before I fell backwards reaching the length of the cables, pulling them out if my hands
I fell to the floor unable to talk shaking like crazy for several minutes. I felt a quivering thru me for hours.

I went to the Dr as my heart seemed to be skipping for several days. He said it would. I've had skipper beats ever since.

With the current going thru me I couldn't see and kept thinking that I was going to die..
I since fixed the hole in the handle and do things much differently now.

Would the same amps with DC have been any different?



.

 

[k0ua]

I was welding at 125 amp Ac, and it was an awful hot humid day. I had to change the ground cLamp positions and left the welder running while I did it. One very sweaty hand on the ground clamp and the rod holder in the other very sweaty hand. There is a hole in the grip of the handle where you can access the set screw that attaches the cable and the handle was also soaking wet with sweat.

I could feel the current going in one hand, across my chest to the other hand. Everything went dark, I shook violently, it melted my wedding ring, burned my fingers, and caused a spasm in my finger muscles that dislocated a finger. I could not move, let out a loud "aaaaaaaàhhhhhhhhhh", my wife heard me,ran into the garage and flipped off the breaker but not before I fell backwards reaching the length of the cables, pulling them out if my hands
I fell to the floor unable to talk shaking like crazy for several minutes. I felt a quivering thru me for hours.

I went to the Dr as my heart seemed to be skipping for several days. He said it would. I've had skipper beats ever since.

With the current going thru me I couldn't see and kept thinking that I was going to die..
I since fixed the hole in the handle and do things much differently now.

Would the same amps with DC have been any different?



.

Wow, that didn't sound like much fun. I have never been bitten by a welder, but I have had a few hits from old tube type TV's back when I worked on them. One was near lethal. 330 volts from a supply capable of at least 1/2 an Ampere. The good news was the path was in a finger and out my forearm.. NOT across my chest..Thankfully. It still took a lot of starch out of my 19 year old body. But I believe your NDE (Near Death Experience) sounds about 10 times worse than mine.

 

[Shield Arc]

Would the same amps with DC have been any different?

WOW, oldpilgrim that is a horrible story!

Working marine construction here is the North West we get hit all the time with DC welders running wire feeders, in the 300 to 400-amp range. Its more of a oh **** kind of thing:shocked:. 30-seconds later you have already forgot about it.

 

[skyhook]

Here's my understanding ( and I could be wrong ), AC goes from a negative value to a positive value, doing so, it crosses the "zero value" line, making poorer welds than a DC welder which has a "steady" value of current. Expert welders compensate for this constant change in voltage/current drop on AC. Personally, I use my machine on DC only, I like the welds better.

 

[Ed of all trades]

WOW, oldpilgrim that is a horrible story!

Working marine construction here is the North West we get hit all the time with DC welders running wire feeders, in the 300 to 400-amp range. Its more of a oh **** kind of thing:shocked:. 30-seconds later you have already forgot about it.

I was working in a shop building stairs and railings. I was welding a couple big pieces of channel together with a DC stick welder and saw a symbol on the prints that I did not know and asked the bosses son what it was. We were leaning on the grounded welding table looking at the prints. I still had the stinger in my hand and he reached up and grabbed me by the front of my shirt and pulled me down closer to the prints. The end of the rod hit him between the shoulder blades and He started side stepping across the shop waving his arms up and down and shouting WOOOOP WOOOOP WOOOP. He did that about 15 feet across the shop and ended up between the pipe bender and a table and started cussing. After a bit he asked "How did I get over here?". That has been over 30 years ago and I bet he has not forgotten it yet, I know I never will. Ed

 

[DXN1EL]

Not all the time, but sometimes I can feel the current when I touch the electrode and the grounded table.

 

[DXN1EL]

Here's my understanding ( and I could be wrong ), AC goes from a negative value to a positive value, doing so, it crosses the "zero value" line, making poorer welds than a DC welder which has a "steady" value of current. Expert welders compensate for this constant change in voltage/current drop on AC. Personally, I use my machine on DC only, I like the welds better.

I thing i read somewhere that it does this 60 times a second and the DC if IIRC is like 60,000 but not sure probably need to look on that