Unplugged welder: Possible fire Hazard?

[Norsk]

I hope this is a simple question that someone with the right knowledge can answer. Does a unplugged mig welder store any electrical current that could possibly constitute a fire hazard?

I have a very specific insurance policy on the shed I rent because previously it was used to store motor boats. I have a disassembled mig in there as well as another Mig and Arc welders.

Thankyou in advance

Mike

 

[Toxic_Avenger]

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.

 

[Jack Ryan]

I don't see a fire hazard. There might be some charged capacitors inside but I think they are no more likely to start a fire than a TV set that is unplugged.

What else is in the workshop? I think cheap plug-paks are more likely to start a fire.

The main problem is the lack of a definition of "fire hazard". I look around my workshop and I don't see a fire hazard. If an insurance assessor looked, he's see everything as a fire hazard if it helped with non-payment of a claim.

Jack

 

[voipio]

The bleed resistors across the main capacitors in an inverter type welder will make sure that they are discharged pretty quickly without power from the mains. The caps will be down to millivolts within a few minutes. Even a freshly switched off welder isn't going to be a fire hazard, and a disassembled one even less so. Now weld sparks are a different matter. It's always best to stick around for at least half an hour after stopping welding, just in case.

 

[Jack Ryan]

It's always best to stick around for at least half an hour after stopping welding, just in case.

Hence the need for a fridge in the workshop.

 

[gt6s]

Hence the need for a fridge in the workshop.

WITH BEER IN !

 

[Screwdriver]

I hope this is a simple question that someone with the right knowledge can answer. Does a unplugged mig welder store any electrical current that could possibly constitute a fire hazard?

I have a very specific insurance policy on the shed I rent because previously it was used to store motor boats. I have a disassembled mig in there as well as another Mig and Arc welders.

Thankyou in advance

Mike

No but welding is in itself an extreme fire hazard. I learn almost to my cost that anywhere you're welding, you need to perform a comprehensive fire risk assessment. Get rid of anything flammable. Every time.

 

[colnerov]

WITH BEER IN !

...and a fruit based drink for the ladies.

 

[MetalMonkey]

I hope this is a simple question that someone with the right knowledge can answer. Does a unplugged mig welder store any electrical current that could possibly constitute a fire hazard?

I have a very specific insurance policy on the shed I rent because previously it was used to store motor boats. I have a disassembled mig in there as well as another Mig and Arc welders.

Thankyou in advance

Mike

While some electrical charge may (or may not) be retained in the capacitors, it will not be enough to start a fire if the machine is switched off and unplugged from the mains.

However, when in use parts of it will be hot, along with any welding spatter, and the items you are welding - so in addition to keeping your welding area free from anything flammable, I would suggest you should always conduct at least a standard 30 minute fire watch after using it and before you put it away - just in case anything is smouldering.

 

[slim_boy_fat]

...and a fruit based drink for the ladies.

Some Ladies drink beer too.....

 

[brightspark]

Some Ladies drink beer too.....

i know one that was going to have a contest with my apprentice she said she could drink him under the table any day . her and her hubby 13 pints a nite each 12 pints and 3 shorts when i was a lad and still rode home on my mororbike

 

[slim_boy_fat]

her and her hubby 13 pints a nite each

Do they know there's a shortage of livers?

 

[Hopefuldave]

...and a fruit based drink for the ladies.

Juniper berries are fruit, arent they? And sloes?

Dave H. (the other one)

 

[Norsk]

Really good advice.

Thank you all. With a special mention to Toxic Avenger for his comprehensive reply

 

[Red'n'Black]

No but welding is in itself an extreme fire hazard. I learn almost to my cost that anywhere you're welding, you need to perform a comprehensive fire risk assessment. Get rid of anything flammable. Every time.

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...

 

[Jack Ryan]

WITH BEER IN !

Something else goes in fridges?

 

[Hopefuldave]

Something else goes in fridges?

Superglue... Chemical camera fillums...

Dave H. (the other one)

 

[Jack Ryan]

Superglue... Chemical camera fillums...

Dave H. (the other one)

Each to his own recreational habits.

 

[Screwdriver]

Something else goes in fridges?

Uhm, yeah err, isopropyl alcohol, acetone, meths, toluene and a dash of methylene chloride.

It's an expensive hobby. Luckily I bought that jug of IPA just before the price went ballistic, still using the same bottle now (for handwash!). Though I must admit, I often wonder if keeping that cocktail in there is any sort of health risk. Assuming I don't drink it.

Obviously the low temperature is much better at keeping these highly solvent liquids contained in their respective bottles.

 

[Jack Ryan]

Uhm, yeah err, isopropyl alcohol, acetone, meths, toluene and a dash of methylene chloride.

I don't keep any of those in the fridge - crikey, that's where beer goes!