Electric disconnect when tack welding frame?

[jon carpenter]

I need to have several small steel clips tack welded onto the steel frame of our Casita. Does the battery, any of the 12 volt, the convertor or any other electric devices need to be disconnected before welding? Don't want to fry any of the electric system. I tried a search and came up empty handed.


thanks....jon

[Casita Greg]

I do a lot of welding on my trailer frame and I never disconnect anything electrical, either 120 volt or 12 volt. Never had any problems. Your circuit path is from your welding electrode back through your welder's ground clamp. A few pics of my welded rear bumper, cross brace, and 2" receiver just for examples.

[jon carpenter]

Thank you Greg for the speedy reply. That's what I assumed but just wanted to double check because I'd hate to fry a convertor or anything electrical. I want to run a quick disconnect from the gas line and need some way to mount the clips for the copper tubing.



Nice welding job. If you were closer I'd pay you to weld on the clips.


jon

[Dennis mn]

The biggest risk when welding on a vehicle is damaging wheel bearings if you ground clamp is not securely fastened to the frame. If it,is; no problem.

[TomE11]

There are two issues. One is that the electrical spikes from welding can damage sensitive electronics. The second is if something is in the current return path to the ground clip. Like wheel bearings, as one poster mentioned.

When welding on cars, I disconnect the battery negative and have never had a problem. I also keep my welding ground clip near the work, something that makes sense anyway.

That inverter.... I would tend to disconnect your electrical ground just because it might, one time in a hundred, make a difference. And it only takes a moment.

[Phil 4500]

My 3 way fridge hasn’t worked on 110 ( it still works on propane and 12v) since I welded up some holes on my trailer frame last year.. I don’t know if it’s related or not.

[jon carpenter]

Dennis, just curious.....how what can happen to wheel bearings if the ground clamp isn't securely fastened?


jon

[Steve Carlson]

I imagine the current will seek the actual ground (via the wheels) if it cannot return to the welder because the circuit is not complete.

[Casita Greg]

Through the rubber tires? Sorry, I'm just not seeing that happening to the wheel bearings.

And especially if your trailer is plugged into your shore power outlet, you already have the chassis grounded when you are hooked up to the incoming power service, (aka path of least resistance.)

Not that it would have any effect on any welding done to the trailer. There has to be a complete circuit, which has to come from and return back to the welder in order to weld. Like all electrical wiring, if you don't have a complete circuit you don't have electrical flow, so if your welder's ground clamp isn't making good contact, you won't be doing any welding.

[TomE11]

Right. I can see the bearings having trouble if you put the welder ground clip on the wheel hub and weld elsewhere on the trailer. That's really the only case.

[Doug Arthurs]

I wouldn't bother disconnecting. I have welded on many a car and trailers and never had a problem with voltage damaging anything.

[Dennis mn]

Originally Posted by Steve Carlson

I imagine the current will seek the actual ground (via the wheels) if it cannot return to the welder because the circuit is not complete.

Absolutely correct. The current will damage either the bearing rollers or races.

I worked for a company that built rail cars. Weldors grounded to the rails. The company built the cars on junk trucks then changed them before shipping.

[Casita Greg]

Originally Posted by Dennis mn

Absolutely correct. The current will damage either the bearing rollers or races.

I worked for a company that built rail cars. Weldors grounded to the rails. The company built the cars on junk trucks then changed them before shipping.

Sure, if you are grounding through the rails and then welding on the frame you're routing your welding current path from the rails and up through the wheels to the frame. I agree that setting up your welding ground in this manner will result in running the current through the bearings, but if you are welding on your trailer's frame and have your ground clamp attached to the frame, there is no way that the current will run through the wheels and the bearings. And, just my opinion, but any welder that grounds his work in that manner should go back to school and learn the basics of proper welding and grounding of their work.

[Casita Greg]

Originally Posted by Steve Carlson

I imagine the current will seek the actual ground (via the wheels) if it cannot return to the welder because the circuit is not complete.

And just how does that happen when it is sitting on rubber tires? Electricity will take the path of least resistance, and since the welder isn't grounded to earth, this statement makes no sense.

[ntsqd]

It isn't just the direct welding current that can be a problem to electronics. Stray and eddy currents can also be detrimental to any electronics not well shielded and filtered. Disconnecting the ground cable is only partly successful when welding on late model vehicles. There are special suppressors made to combat the problem. A shop owning friend has one of these and when I asked about it he told me that clamping the suppressor onto the battery terminals is better at protecting the vehicle than totally disconnecting the battery. It is also faster and doesn't trigger the ECU having to re-learn the engine.


With a trailer those electronics aren't nearly as common. I'd think that disconnecting the battery ground should be sufficient. If you're concerned about any of the electronics then disconnect them and make sure that their housings are well bonded to the chassis.

[Eyeball]

Originally Posted by Doug Arthurs

I wouldn't bother disconnecting. I have welded on many a car and trailers and never had a problem with voltage damaging anything.

Well...there is the possibility of a current spike which can energize anything connected to the frame for less than a millisecond, enough time to do damage to any semiconductor or similar components. Current is equivalent to Amps and Amps love semiconductors 'cause they fry real quick like and stink, snap and crackle, even pop!...fun!
There is a reason why "they" always nag you to disconnect anything electronic before doing any work on stuff the electronics are conected to, in this case welding on a frame.
But no worries, only Rebels will ever experience these spiked fry sessions if they happen, and although I am a Rebel myself (my ex says I am too) and never had any problems, I am still taking chances, it's somewhat like Russian Roulette, and once reality has made an entrance and wasted an irreplacable item, it will make more sense.
But as a newby to the forum I should be careful to not say too much, so that's it.
Cheers.

[stevebaz]

Disconnect the battery and unplug the shore power cord if plugged in. That way any stray, if, or, ands and buts crop up they wont befall your trailer. Better safe than sorry. And please have a live garden hose near buy and or fire extinguisher near buy. And if you love your home don't weld in the garage move the process outside if you can. In the right circumstances one small mistake can lead to a very bad day.