Unplugged welder: Possible fire Hazard?

[Parm]

Trouble is, after I've finished concentrating on laying down that nice tidy bead while trying to ignore the flickering orange light coming from somewhere, the flammable thing turns out to be me...

Yep, ive had that encounter too, but only when using the angle grinder

I can confirm that the flame proof overall are indeed flameproof, but they dont half smoulder

 

[premmington]

On inverter machines, and talking about the ones I've looked in - usually the input plug goes to a AC filter board, then to a bridge rectifier and then onto a capacitor bank - sometimes 4 or more 400uf caps - big buggers holding 400V. Essentially all welders do is convert wall power (high volts, low amps) into welding power (low volts, high amps) - just like how a gearbox might change engine RPM into wheel RPM. In the absence of input power from the wall outlet, It's the residual voltage stored in capacitors on the input side of the transformer that will be most dangerous.

Some machines will discharge these big capacitors as a shut-down procedure (fan may run for an additional few seconds, machine lights may flicker), and other times, these capacitors can drain over time. To test, carefully put a multimeter on the capacitor terminals, and you'll see if they hold voltage. If they do and you want to discharge them, short the two capacitor terminals thru a 100W lightbulb, or other large, reisistive load. Do not put your fingers near these caps - 400V is not pleasant.

In a perfect world, the un-initiated will not be poking about inside welders, nor would they have them to the point that they are in pieces and exposed to poking fingers etc... but as a device, they are perfectly safe to have in storage when assembled. The electrical standards applicable to the country they were manufactured in / sold in, would ensure this is the case.

Both invertors I have do this.