Welding (arc) what to disconnect to prevent damage

[Bikersmurf]

I've got some cracks in the cross-member near the lower rad mounts on my 97 E350. If I dont just pull it out, what should I disconnect to avoid damaging electronics/electrical stuff?

On older trucks, I've disconnected the alternator... if I bothered at all.

I know there are fancier welders, but I'll most likely use my 100A/110v NAPA stick welder with some 5/32 Farmers rod. At +/- 70 amps, I've had good luck on thinner sheet metal. The steel of the cross=member is much heavier gauge so I'm sure it'll get the job done. Once welded, key stress areas will likely be reinforced.

Thanks

 

[IdaSHO]

I wouldnt worry about anything. At the most Id simply remove the ground cables from the batteries.

Just put the ground clamp close to where you are welding, and you should be fine.

 

[Herbie]

Can't help with your original question but wanted to offer an extra bit of advice since you'll be stick welding in an unconventional position: SILICONE EAR PLUGS.

Not just the little foam disposable ones. My welding teacher is deaf in one ear after slag burned through the foam and his eardrum while he was welding in an awkward overhead position.

 

[luthj]

For safety (more than to prevent damage) disconnect the battery negative.

Make sure you are well grounded close to the weld area. Directly to the cross member works. Then go at it. I would not weld within about 24 inches of a sensitive component such as the ECU, or other electronic module. That is about it though.

Since all the electrical potential is between the ground and electrode, there is no potential across any of the other electrical parts in the vehicle.

 

[philos]

I use one of those surge protectors like the muffler shop uses. Protects both batteries without disconnecting.
Found mine on Amazon a few years back.


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[bajarat]

Disconnect Pos and Neg battery terminals and zip tie to each other.

 

[Bikersmurf]

Good to know... I think in this case, disconnecting the 4 batteries would be a bigger PITA than just removing the crossmember I need to weld up... Next time may be a whole different story.

I had been on the fence. But, as always, doing it the right way will likely be best. At this point, I wish FORD hadn't hung the rad on sheet metal, but instead had it mounted to the truck frame. Now to find a day which I can spend on this repair... Or find a crossmember that's not fracked. This is the downside to a rig with 200k miles and 15k hours on it.

 

[threej97]

I would disconnect the computer as well. We had an old dodge that an employee did some welding on a hitch mounted receiver vice. After that our fuel milage went from 12 to 8.

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[IdaSHO]

That must have been one heavy hitch :sombrero:

 

[madmax718]

Can't help with your original question but wanted to offer an extra bit of advice since you'll be stick welding in an unconventional position: SILICONE EAR PLUGS.

Not just the little foam disposable ones. My welding teacher is deaf in one ear after slag burned through the foam and his eardrum while he was welding in an awkward overhead position.

OMG.

 

[luthj]

Can't help with your original question but wanted to offer an extra bit of advice since you'll be stick welding in an unconventional position: SILICONE EAR PLUGS.

Not just the little foam disposable ones. My welding teacher is deaf in one ear after slag burned through the foam and his eardrum while he was welding in an awkward overhead position.

OMG.

If welding out of position, a nomex or splash proof head covering is advised. Scary to think about.

 

[broncobowsher]

I leave the battery connected. That is a huge capacitor, absorbs spikes very well.

 

[tgreening]

Electricity loves path of least resistance. Make sure your welder has a good ground, as close as practical to your work, and have at it.

You ever see those movies where someone dies because some baddie tosses something electrical like a radio or blow drier into the bath tub/swimming pool/jacuzzi, etc? It's complete bunk.

 

[Bikersmurf]

Electricity loves path of least resistance. Make sure your welder has a good ground, as close as practical to your work, and have at it.

You ever see those movies where someone dies because some baddie tosses something electrical like a radio or blow drier into the bath tub/swimming pool/jacuzzi, etc? It's complete bunk.

Other than pure HOH being a poor conductor of electricity and HOH with salt in it (ie our bodies) being a much better conductor... And if the tub is enameled or Acrylic the electricity will take the path of least resistance to the grounded brass drain pipe.

I'd not bet the house on surviving. Chances are you'd not be fried before the GFI trips though.

 

[luthj]

Other than pure HOH being a poor conductor of water and HOH with salt in it (ie our bodies) being a much better conductor... And if the tub is enameled or Acrylic the electricity will take the path of least resistance to the grounded brass drain pipe.

I'd not bet the house on surviving. Chances are you'd not be fried before the GFI trips though.

Mythbusters (and other scientific studies) show that stray electrical current in water can be deadly. This is why building codes require GFCI protection near water sources. It only takes 50mA or so across your heat to cause it to stop. 10mA across muscles is enough to cause temporary paralysis. Look up electroshock drowning.

Electricity doesn't just take one exclusive path. Assuming the dielectric value of the media is below the the voltage potential, current will flow through the media (water etc). The current flow/distribution will be proportional to the resistance. With only 50mA needed for the risk of death, it doesn't take much stray current in water to cause issues.

Because welders use a fairly low voltage, and because the voltage differential is almost exclusively across the arc itself, there is only a few volts of potential in the frame or weldment body. This means getting shocked (or damaging equipment) due to stray electrical current when welding, is highly unlikely. This is assuming a good ground contact to the weldment/part.