Welding on TT

have never damaged anything on trlr or trk. Keep the grd as close to the work as possible. The current is gonna flow between the two, not running all over the rig.

If stray welding voltage does find its way to an electronic component it can't flow through it because there is no longer a complete circuit with the battery neg. lead disconnected. And if the current can't flow through it the component it is much less likely to be damaged by it.

Anytime you do anything electrical on a vehicle these days it is standard practice to disconnect the battery. Not every wire sees voltage, some see only data signals, and accidentally applying voltage to the wrong wire can toast a circuit board. I know my burb has 5 separate computers in it and they are connected by their own on-board LAN.

I know TT's are much simpler, but you still have circuit boards in the fridge and furnace, along with a radio, TV, etc.

Theory is that the current has a harder time traveling through electronics.Standard practice in welding shops.

How exactly is removing the ground from or disconnecting a battery going to prevent any damage?

In all my years spent in machine\welding shops no one has ever explained why taking battery cables off serves any purpose.

The only story I've ever heard was a welder got a pretty good thump when a spark bounced of something in an engine compartment and lit up a gassy battery that had been covered with a board.

I used to be a certified welder at a nuclear plant. I have wore digital watches since the early 1980s. Some folks would wonder why. It doesn't take long for welding current to ruin a regular mechanical watch by magnetizing it.

I was welding a small project on the bench one day. I was using an AC "buzzbox". probably a Lincoln, IIRC. Even using standard leather welding gloves, my wedding ring heated and deformed from the the stray current. Those electrons can be slippery little bast&^ds. IMO, there's no reason to not err on the side of caution and remove the battery and electronics from the steel being welded. Besides, it gives a guy an opportunity to clean and renew the terminations.

I would agree, ground placement protects the electronics...in theory. If for some reason your ground isn't as good as you thought it would be, for the 5 mins it took to disconnect the negative battery cable and unplug shore power, you don't risk damaging pricey things like the circuit board in the fridge.

69 Avion wrote:
I have seen people building trailers and they were lazy and used the steel jig for the ground. It made it easier to move the trailer because they saved a few seconds that it took to move the ground when flipping the trailer over. Once the axles were installed they would flip the trailer back, right side up and finish some welding. The trailer was grounded, from the jig, through the steel hubs to the trailer. The new owners couldn't understand whey the bearings didn't last long.
As far as disconnecting the battery, it is just a precaution that I take. If you don't have any sensitive electronics then it probably isn't an issue. I would rather give advice using caution instead of costing someone a lot of money because they took a short cut. YMMV

Wasn't on a trailer, but a buddy wasn't really thinking when he was doing some welding building a smoker. never though about the ground, left it on one place while welding everything, including welding the common bullet like hinges to the frame and moveable cover and some 1" flat stock to the opening door and likewise to the firebox. then came the suprise. Doors would barely move. Humm... then it dawned on him, got the hinges to move, seperated them and the were gaulled to almost destruction. All that welding current going through the hing joint ended up with a bunch of "spot welds" on the hinge posts from the high current and heat buildup.

Always THINK when you attach the ground clamp. Where is the current going?? It will keep you from damaging stuff, either mechanical or electrical.

personally, I turn off the propane, use the battery disconnect switch and disconnect shore power. Is it needed?? probably not, but it is really easy to do, especially turning off the propane.

69 Avion wrote:
I have seen people building trailers and they were lazy and used the steel jig for the ground. It made it easier to move the trailer because they saved a few seconds that it took to move the ground when flipping the trailer over. Once the axles were installed they would flip the trailer back, right side up and finish some welding. The trailer was grounded, from the jig, through the steel hubs to the trailer. The new owners couldn't understand whey the bearings didn't last long.
As far as disconnecting the battery, it is just a precaution that I take. If you don't have any sensitive electronics then it probably isn't an issue. I would rather give advice using caution instead of costing someone a lot of money because they took a short cut. YMMV

I believe this is good advice. I would unhook battery and any electronis especially ones with boards in them. Risk is not worth the reward.

I have seen people building trailers and they were lazy and used the steel jig for the ground. It made it easier to move the trailer because they saved a few seconds that it took to move the ground when flipping the trailer over. Once the axles were installed they would flip the trailer back, right side up and finish some welding. The trailer was grounded, from the jig, through the steel hubs to the trailer. The new owners couldn't understand whey the bearings didn't last long.
As far as disconnecting the battery, it is just a precaution that I take. If you don't have any sensitive electronics then it probably isn't an issue. I would rather give advice using caution instead of costing someone a lot of money because they took a short cut. YMMV