Thread: Welding out on site ? ? Generator? My Mig

Hi ,
Ive got an older , 8 to10 Years old, BOC 250 C Mig welder .

I will be needing to weld out in the paddocks on a farm . Im thinking of a roof over 2 x 40' shipping containers with a 8 Meter space in between them .

Carting a Mig and bottle around in the ute with a generator will be my first choice but that depends on the generator I will need .

If its to big I may go back and buy a smaller arc welder , a CIG 170 or Boc 170 and a generator for that and the other tools I want to run while doing this work. Cut off saw drills and angle grinders .

so question is , what size generator for running the 250c Boc Mig .

This is a later machine but the specs should be the same ?
BOC Smootharc Advance II MIG 250C Welder | BOC Australia

I rang BOC and was played an earfull off adds and music while being placed on hold, and the nice girl got back to me and said 30 to 40 KVA ?? sounds way to big or is she right ?

I saw a post here on a generator for the 170 arc welders ,and I think someone here said 7 KVA . Id have to go check .is that right ?

Thanks Rob

I run my 250 transmig off a 6.5kva generator. Of course that is just at about 2/3rd of flat out setting. It would not run it flat out, need 12KVA for that according to the plate on the welder.

So an 8kva would do what you want easily.

Not sure what drugs they were on to say 30 to 40 KVA, unless they were meaning a 3 phase generator which each single 240V outputs (it would have three of them) is usually only 1/3rd each of the total three phase output.

I bought a 5 kva get set to run a 140amp welder. Sales bloke in Karratha assured me that it would easily run the welder. (wrong).

Gen set on full noise and using the smallest electrodes on the stick welder, barely able to strike an arc. Might be different these days if you use an inverter welder on that size Gen set, certainly not big enough for the old Transarc 140.

DD

Sounds like you have experienced the same lack of knowledge from the BOC muppets that I have.
The 250C has an inbuilt wire feed I believe. That in itself could be a bit of an issue if you are working off a ladder when building your roof. You may need to look at self shielded wire if there is too much breeze blowing.
As others have correctly said, it will take a fair size generator to run your welder at full noise, but at more realistic amperages, an 8kVa will probably be adequate.
To be honest, I don't usually picture mig welders as site machines, they can do the job provided you can address the portability and wind issues.

I once tried my little BOC Smootharc 130 stick machine off a cheap-arsed Bunnings 2kVA genny (which, despite assuming it'd be a cheap POS, has proved to be an excellent machine - starts every time first pull and just runs). With a very careful striking technique (any sticking would kill the genny), I was just able to run a 2.5mm rod at about 80A from very dim memory. Which wasn't that useful for what I needed to do at the time, but may get me out of trouble at some point in the future.

Originally Posted by Karl Robbers

To be honest, I don't usually picture mig welders as site machines, they can do the job provided you can address the portability and wind issues.

Looking into it a bit more , some of those generators at 8 to 10 KVA Ive seen are heavy 5 to 600 KG . It looks like the smart way to do what I want is just to weld the brackets that tie the roof to the containers edge and weld any thing else up on the ground and assemble and bolt from there rather than welding up higher. Just like shed roofs are done .

What is a good way to go with site work ? just a 170 amp arc and generator?

Or one of those arc , mig tig packs and generator ? are they the inverter ones ?


Rob

Originally Posted by auscab

What is a good way to go with site work ?

I've seen welders on site with big generator combinations (welder integrated into the set up) and with the small lunchbox inverters if power is on site. Can's say that I've ever seen someone arrive with a separate genny and plug a welder in. It is suggested that my 200A inverter needs a minimum generator of 6kVa, so as you have said, you are looking at a heavy box if you go the separate unit way.

Michael

I've found a 6.5-8kva generator to power your power tools and an inverter is a good site set up.

long heavy duty leads are necessary if stretching your work distance.

allows you to run a 3.2 mm rod at good heat.

Originally Posted by Dingo Dog

I bought a 5 kva get set to run a 140amp welder. Sales bloke in Karratha assured me that it would easily run the welder. (wrong).

Gen set on full noise and using the smallest electrodes on the stick welder, barely able to strike an arc. Might be different these days if you use an inverter welder on that size Gen set, certainly not big enough for the old Transarc 140.

DD

Generators are not all equal.

We have an ye old 5KVa dunlite, it runs a 140 amp stick welder easily.

I have a 6.5Kva miller welder/generator and the generator on it can not hold the voltage levels under load like the 5kVa dunlite can.

I have an old Lincoln 175 Weldandpower AC combination unit driven by a Lombardini single cylinder diesel. I use this for jobs away from power outlets on my 8 hectare rural residental block. Easily runs 3.2mm electrodes and ok for power tools such as grinders and drills etc. Wouldn't try powering any electronic items because 240V ac output voltage is not really stable.
These old type generator/welders should be cheap to buy. Bought mine at a farm clearance about 10 years ago.
Lincoln Weldanpower 175P AC.jpg

Gerry