I’m no electronics expert, but my understanding is that most such devices operate in the 1 to 2 volt range, and with current in the milliamp range - that’s 1,000th of an amp. So you can see that if the welding current was occurring near the connection points for the “ground”, housing, or operating devices, there would be a risk to the electronics just from the massive size of the nearby current and associated voltage - kind of like a mouse playing with an elephant !
More likely, I think, are stray currents and voltages that are induced into the metal carbody by the magnetic field from that heavy current of the welding. Each time the arc is made or broken, the current starts or stops, and a magnetic field is created or collapses, respectively. When that happens, the field induces or ‘reflects’ a current in anything metal nearby, and that could be enough to fry the delicate circuitry. Here’s a little test: Put a portable radio playing an AM station right next to a welding operation some time, and see if static can be heard when the arc is struck and broken. If it can, that proves my point; if not, then it’s bogus. Note: I’m not responsible for damage to the radio !
I’d be more concerned about the induced voltages from breaking the arc than from making the arc - the spark from the mechanical ignition systems on older cars was created when the points were opened, not closed. If the current path is close enough to the electronics and the break generates significant high frequency components (order of 1 MHz or so), then it is possible to fry electronics. If the distance between the point being welded and the ground clamp is small compared to the distance to the “sensitive” electronics, then damage is unlikely.
I’d be REALLY surprised if arc welding didn’t cause interference to a nearby AM receiver. One point - cable layout will make a difference in the amount of interference, keeping the two conductors as close as possible to each other will reduce the amount of interference. Another point - much of the interference from DC welding will come from the diodes (reverse recovery).
FWIW, I am an electrical engineer and one of my specialties is RF circuitry.
Electricity does NOT take the “shortest route”, it takes ALL routes, with the amount of current in any part of the routes in inverse proportion the resistance of that part of all of them.
With large multi-part rivited equipment, if the parts the electrodes are connected to (the so called “Ground Clamp” and the welding rod) are not just one part, then there exists the possibility that the resistance between the two parts is high due rust and corrosion and thus current might flow to other parts that might put current into other connections to electronic components (so called “stray currents”).
In addition, when the arc is struck there is also an electromagnetic pulse (EMP) given off that can induce currrents in anything that will conduct electricity, such as metal panels,wires, and electronic circuitry. It is quite possible for the EMP to fry a digital wristwatch on the operator of the welding equipment, or even someone standing nearby (rare, but possible!).
I am not a welder… I am the poor sap that has to go repair the result of someone welding on something without taking into consideration what WILL happen if things are not quite as they assume.
It was really hard to convince a fellow that his battery powered, (even turned off) laptop PC needed $$ repair (took out the touch pad, audio amp AND speakers) because it was on the shelf next to the work bench where he was doing TIG welding. Well… At least not until he discovered that his pocket calculator in his shirt pocket no longer worked either.
I have seen and repaired the results of someone welding on something that should have been consulted with before. We once had an outside contractor (certified bridge and highway welder) come in and do some repairs on one of our jaw crushers. No one noticed where he put the ground clamp. When it came time to start the crusher the bearings in the pitman were welded together from the current passing through. It only cost $12,000 for the six bearings and a weeks down time with over one hundred man hours labor and a crane rental. It turned out he attached the ground to the flywheel. That was the last time we hired an outside contractor. It turned out to be cheaper to pay the overtime to the employees to do maintenance.
Another time was when a plant foreman was fabricating crusher parts on the tailgate of the service truck/welder. When it came time to leave it would not start. The engine computer was fried. He did have the ground attached directly to the pieces he was welding and it still fried the computer.
So don’t tell me its ok to weld on something with and without electronics without taking precautions first.
Several excellent and expanded explanations above that directly address the questions raised by the Original Post - from those who are technical experts and/ or experienced in the subject. [tup] I rest my case. [swg] Thank you. [bow]
We are just going to have to agree to disagree on this one. I think it is hard for people to understand welding unless you have been the person doing the welding. In my case I have not only welded as a career on locomotives and railcars but I have also welded on amusement park rides,ship yards cranes,automobiles,trucks and trailers,and as a contractor for the US Army. I also spent 3 years working with robotic welders in a factory. In that 25 plus years of all those jobs I have yet to fry any electronics of any kind including the computers on the 3.5 million Army Strykers.
What you people are failing to understand is many things and one of them is the basic principles of electricity and grounding. When you ground a locomotive or rail car or any piece of metal the entire object is grounded. It doesn’t matter where the ground is located because you can strike a arc anywhere there is steel. Electricity will always travel the path of fastest and least resistance to the ground. In welding that ground is always the ground cable coming out of the welder which is typically no more than 6 feet away. If the electricity was traveling anywhere else you wouldn’t be able to weld anything because you wouldn’t get a arc to begin with. If you are getting a arc then the electricity is flowing from your rod straight to the ground creating a controlled short circuit resulting in a electrical arc and heat. It is doing exactly what it is supposed to be doing. It’s not going anywhere else including taking paths of more resistance including computers.
This idea that when you try to strike an arc and the positive electricity can somehow travel through the grounded metal into a computer or other electrical device and fry something is just not possible. Every theory regarding electronics is working against you. The electricity has already found the path of least resistance and made contact with the ground and has nowhere to go nor does it want to go anywhere else. It’s simply impossible to have a steel plate that is
Thomas 9011 - I’ve done a small amount of arc welding, and managed others, so I understand most of what you’re saying, and not disagreeing with it. But it’s not just the principal flow of current that could cause a problem. It’s what I’ll call the secondary effects - the magnetic field, which can’t be measured with ordinary instruments - and the small and random voltages that it could induce in the random shapes of steel - “eddy currents” and the like.
I wonder if this little experiment would illustrate the point: Sprinkle some iron or steel filings on a piece of white paper. Carefully lay it on a piece of sheet steel. Strike a couple arcs next to it - just far enough away to not set the paper on fire. See if the iron filings move and arrange themselves in some kind of pattern - probably circular, centered around the arc. I’ve never done this, but it seems like it might illustrate the effect. Then there’s also the radio static test I suggested above, which erikem also seems to believe would demonstrate the effects.
In the end, this question is not really about what you or I think or know, or even what the actual facts are. Instead, it’s that the Herzog people are conerned enough about the potential risk to put that warning on their car.
I was pulling a Reefer Trailer in 99 with a Computer Contorlled Reefer Unit. Well I got backed into at a Truckstop in AZ with a Frozen load that damaged the Trailer and needed it repaired before I could move. The area to be repaired was 52 feet away from the Reefer Unit. Repair required TIG welding. The Welder they hired said I could stay hooked up to the Trailer I did since I had to leave as soon as the repairs were finished. The Welders Currents took out a total of 5 EUC’s on the Trailer and Tractor of the combo Combined. It took out the ABS computers on Both the Tractor and Trailer the Engine ECM which was a TEST one for Detroit that made them REAL HAPPY also took out the Reefer Units and the Trucks body Control Computer. The Repairs to replace the Computers came to over 25 Grand that were billed to the Insurance company of the Welding company Shop. We had even removed the ground Wires form the Batteries of the Truck and Reefer Unit Prior to the Repair being Started.
Our Volvo haul trucks have 5 computers in them. Volvo states in all the repair manuals and decals on the machines warning to unplug the 5 computers before welding on the machine. As an aside. Trucks and trailers and for that matter autos are not grounded to earth. A man I knew for many years got killed when his dump body hit some high tension lines while dumping a load of gravel. The resulting jolt set all 18 tires ablaze and melted every piece of aluminum on the truck and trailer. The current was so massive it welded the steering linkage together and melted the oil pan. His body was found in the cab with his hand on the dump lever.
One small loss of contact with ground will force current to find the next available path That next path will be anywhere you don’t want it to. Ask any welder with more then a month of experience what happens if his feet are damp and he tries to change a rod. Even though he is grounded he will still get that twinkling in the toes. Every welder I know always has dry socks.
The welding arc can even provide interferrence to FM radios. When flying in the northeast sometimes you could hear a welder breaking up the squelch. Another item would be either subway cars arcing over or the GG1s arching over on the 12KV lines.
And thanks once again, Ed [tup] - for the quite evident time and thought that went into this comprehensive reply (and others). You must love the business, too - why else spend this much time on it ? [swg]
[:-,] What I’d really like to see from this effect is some kind of electronic field interference gizmo to remotely and quietly ‘toast’ into an enforced silence those overbearingly loud ‘thump-thump’ car stereo boom boxes . . . [swg]
Our company has worked on a couple of projects that had the potential to be very disruptive to toast the car stereo boom boxes - however the toasting would not have been quiet had the stereo been on at the time.
It seems to me that for the most efficient use of the device that the boom box be on–so you will not waste energy while waiting for one to come by. Perhaps the device could have a loudness detector which turns the blaster blaster on when a certain level is exceeded. Of course, there would be the danger that the driver would be so frightened by the sound of the blast that blasts the blaster that he/she loses control of his/her vehicle, with subsequent property damage.
It is a shame that the people who believe that everyone else likes what they like has to continually increase the sound level of their blasters as they gradually lose their hearing.
I have been tempted, when a blaster has stopped by my car to tell the blaster operater that I do have my own sound system, so he does not need to supply me with entertainment.[:D]
Actually the technology would be put to better use as a ‘cell phone blaster’. Triggered against those who prowl the highway with the cell phone at their ear and their attention on their converstion rather than the events of the highway. 10 seconds of 150db noise blasted at their eardrum from close range ought to cure them…