Welding brackets on tractor frame

[LouNY]

I had been told to lift the battery ground connection before welding on any vehicle long before the internet was even a dream.
I have usually lifted the ground cable(s) and have seldom ever had an issue. I did lose a generator one time, was that coincidence or not no clue but it was working before I started the repair and wasn't when I finished the initial repair. Replace the generator and the system worked again.

 

[rScotty]

Seems like there are several opinions. Here's mine:

It doesn't take long to disconnect the battery.

 

[ruffdog]

My Bobcat manual says to disconnect the battery AND unplug the computer before welding.

 

[rScotty]

My Bobcat manual says to disconnect the battery AND unplug the computer before welding.

Good on them.

 

[5030]

I never do but again, I keep the current path as close to the weld point as possible. 20 years and no issues but then my units aren't electronic controlled either. If they were, I'd probably unplug everything anyway.

Welding current will always take the shortest path and least electrical resistance, no exceptions.

Only takes me a second to disconnect them anyway. I have battery isolators on all of them as a theft deterrent when I leave them in the field. Insert key, turn and pull and no circuit.

 

[SylvainG]

And if your FEL and implement isn't on the ground, then there is no current. Tires are pretty good insulators.

 

[Sberry]

What? Feel free to explain that and any real explanation as to how unhook helps anything would be read.

 

[Sberry]

I think some simply put that in manuals as a disclaimer and the guy wrote it doesn't know any more about it than the janitor does.

 

[Sberry]

Think about how a car or truck is wired. If welding current could go thru a battery it would need to be shorted. The world would come to a stop if everything with electronics had to be disconnected.
Couldn't use trucks for welding platforms, the guy with the big Cat service truck has a weld vise on the bumper. Look at all the pipeline rigs, brandy new 1T, north of 70k and welding on the beds. My own, welding work lead bolted to the frame/body bumper.

 

[rScotty]

What? Feel free to explain that and any real explanation as to how unhook helps anything would be read.

I think what he is saying with the tires as insulators and potential paths through FEL and 3pt attachments touching the ground you have a real situation.
I agree, and here is why:
The ground clamped on the welder frame and the electrical supply ground SHOULD be at the same potential if all the grounds and neutrals in the supply circuit and in the welder are connected correctly - but that doesn't mean that they are.
And if they are not, then the potential to ground is not absolute, it is relative. And we know that current can flow between two dissimilar "grounds".

 

[Sberry]

Welding voltage is so low and the earth such a poor conductor this is moot. Earth won't even pass enough current at 120v to trip a breaker.
Secondly sort of the weld work or ground isn't really a ground but a work lead to the transformer or weld side of the machine and has absolutely nothing to do with the supply current,,, and the ground in the equipment conductor got nothing to do with any of this and the connection to earth got not much to do except for lightning and minor step potentials between the ground/floor you stand on and the equipment
Welding circuit and supply not at the same potential, come from separate systems. Leave the work lead open, take stinger to neutral bar and nothing.

 

[Sberry]

If the loader was insulated it would mean no pathway for current. When you get a shock from a welder it's not welder to ground but from secondary lead to lead. If the ground was wet and the loader grounded the ground or earth would be a pathway not a destination.

 

[Sberry]

What would and is a concern is welding current being passed thru a hi resistance connection or small wire. Work lead connected to body and weld on engine or thru parts. I try to have both pieces grounded on a car, think someone mentioned this earlier. I hook ground to engine side and tailpipe by rubber hanger on the other. Essentially forces the arc to the well grounded part.
This is involved in special circumstances around cranes in shops. Got to make sure cables are not used as welding pathways. Same for bonded interconnected benches, not such an issue with single and with some feed 2 wire gfci to prevent building wire ground being used as pathway and have bench "electrically" grounded using the common welding ground which is a rather poor term.

 

[grsthegreat]

I think your absolutely right about ground clamp and welding not going to affect the electronics. its probibly just a old wifes tale.

but, I Wasnt going to risk my friends newer $70k truck when i was welding on rig. I unhooked the battery and made him reprogram his radio later.

 

[Sberry]

I am distracted but I am very deliberate at some specific tasks. My trade is welder but I am pretty crafty with a grinder, I consider which way the dross is going at every turn. I remember the welding instructure in one of his lectures mention a bit about current pathways and it kinda stuck as habit. He wasnt much of a welder but he was a smart sharp guy/mechanic type had been around a little. He worked on equipment over the years more than a true welder and true talent was sending people out where they belonged.
Anyway,,, I thought I might have to pick up a lunch box and panic and almost got a job. I am super glad one of my deals fell thru as it all turned out.
The ultimate gravy job was riding a pickup between a couple local plants Still might be but was thinking a good sized outfit was losing a bunch of opportunity work to other trades and the simplification of structural steel over a bunch of bolt together **** saves a lot of juice.
I dont give a dam about all the frickin wires where they go or what they do.

 

[Sberry]

So, the point of it was babble and back to experience with the direct issue. As I mention,,, 1000's and a big reason I dont do it is the additional work. The increase exposure to collateral damaged due to additional connections, r and r and a job now takes me 10 minutes takes additional hard work of who knows. Most of my own is in pretty good shape but when I was a busy mechanic working overtime might weld on several different things in a day on occasion and a small steady stream right along.

 

[Sberry]

I have the work bonded to the body and vise of my service truck, a Y in the cable and want it so never got to move lead back to the truck, have a poor connection from a clamp. Only potential scenerio is a grounded tool laying on a metal structure and disconnected welding ground, could make the grounding conductor a welding pathway. Feed 2 benches 120V and not move welding ground from one to the other, welding load across ground wires. This happens with welder thaws in the winter also but its another road.
But basically the solution was to bold big ole copper wire between benches. I plug benches in to a circuit with hospital resept, says, no equipment ground, gfci. Should it ever become energized from another source it is electrically grounded thru the welding connection in the floor

 

[Sberry]

My friends 70K new truck with the welding bed on it aint gonna get disconnected every time he hooks a fitting on the pipe vice and welds on it. The experience isnt once or even twice but that every day and same for the muffler guy. Probably more damage to other equipment from this than cars. Easy to forget something in lots of sceneries.
I can say this. I do consider jump start and reverse polarity a potential problem and almost and have done it. I consider it a high risk thing. I rarely consider the potential risk to this particular aspect to potential damage to the car,,,,, its way down my list. Fire is king, cutting, weld and grinding. All this time and I use the blaster once when I shot fire with the plasma inside the door jamb and caught trash and insulation on fire.

 

[Sberry]

So my bud comes over well in to the secod 12,,,, I was sober, but wants a frame fix and I did it crawl under. Calls me up about 30 minutes after he peels out,,,, corksucker, ya set my car on fire. Was burning in his driveway, he manages to get it out. Calls me the next day,,, ****, I messed up and had hanging wires cause the fire.

 

[Sberry]

I guess my point is I would have had to disconnect and reconnect 1000s of batteries and electrical connections to feel better about something I NEVER had a problem with and cant recall anyone I actually know ever did.
I am sure someone somewhere has had, would be surprised or it would be a stretch or assumption, speculation that disconnecting would have helped. It's not insurance, certainly not absolute. Not a guarantee.
Might not mean much to a part time but to someone does this several times a week would be significant

As to a 70k truck I ain't getting under the hood and pulling all kinds of connections, outer connectors, some have multiple batteries and dozens of connectors and in lots of cases wouldn't have a clue where they even went.