Mig welder power supply

tr250

Member
Location
Northants
I’ve just bought myself a mig welder having never had one before I’ve bought an Rtech 250 amp single phase machine and running it off a 16amp blue socket my trouble is it keeps tripping out if I turn it up much more than half or weld for prolonged periods I’ve been trying to do continuous welds 1m long today. Firstly to mig welders take more power than stick inverters as I could weld pretty big stuff with the stick without problems on the same supply?
secondly can I run a single phase welder from a 3 phase supply perhaps in hindsight I should of bought a 3 phase machine but I wanted the ability to move it to other places on the farm not just the ones we have 3phase sockets in?
 

Phil P

Member
Arable Farmer
Location
North West
I’ve just bought myself a mig welder having never had one before I’ve bought an Rtech 250 amp single phase machine and running it off a 16amp blue socket my trouble is it keeps tripping out if I turn it up much more than half or weld for prolonged periods I’ve been trying to do continuous welds 1m long today. Firstly to mig welders take more power than stick inverters as I could weld pretty big stuff with the stick without problems on the same supply?
secondly can I run a single phase welder from a 3 phase supply perhaps in hindsight I should of bought a 3 phase machine but I wanted the ability to move it to other places on the farm not just the ones we have 3phase sockets in?
What’s tripping? The welder or the supply RCD?
I run a 275a mig on single phase no problem even on long welds like bucket blades etc.
 

ACEngineering

Member
Location
Oxon
I’ve just bought myself a mig welder having never had one before I’ve bought an Rtech 250 amp single phase machine and running it off a 16amp blue socket my trouble is it keeps tripping out if I turn it up much more than half or weld for prolonged periods I’ve been trying to do continuous welds 1m long today. Firstly to mig welders take more power than stick inverters as I could weld pretty big stuff with the stick without problems on the same supply?
secondly can I run a single phase welder from a 3 phase supply perhaps in hindsight I should of bought a 3 phase machine but I wanted the ability to move it to other places on the farm not just the ones we have 3phase sockets in?

You need more amps to weld with a mig to weld the same bit of steel you do with a stick.

250amps is probably going to weld 10 or maybe 12mm thick max imo, you just wont get the penetration like a stick using less amps!
And more passes with a mig isnt the answer like multiple passes with a smaller than ideal rod on thick stuff using a stick which is slow but you can get away with if needs must.

Maybe need a less sensitive RCD trip? Or upgrade wiring?
 

dave mountain

Member
Livestock Farmer
Thats a fault not a power issue. May be a fault on the welder if the fault is only causing the RCD to trip over half power, or could be one of the supply cables getting to hot. If it was a power issue the MCB would trip, not the RCD.
could you take a picture of the consumer unit?
 
Last edited:

tr250

Member
Location
Northants
You need more amps to weld with a mig to weld the same bit of steel you do with a stick.

250amps is probably going to weld 10 or maybe 12mm thick max imo, you just wont get the penetration like a stick using less amps!
And more passes with a mig isnt the answer like multiple passes with a smaller than ideal rod on thick stuff using a stick which is slow but you can get away with if needs must.

Maybe need a less sensitive RCD trip? Or upgrade wiring?
Yes that’s what I’m finding where I needed 100 amps with the stick I need 150. The wiring is pretty good I’d say it’s a newish 5years maybe board and is a 3phase supply having 3 phase red plug, blue 16amp and normal 13amp sockets coming off of it. I think the rcd is a C so shouldn’t be over sensitive
 

tr250

Member
Location
Northants
Thats a fault not a power issue. May be a fault on the welder if the fault is only causing the RCD to trip over half power, or could be one of the supply cables getting to hot. If it was a power issue the MCB would trip, not the RCD.
Should a 16 amp supply run a 250 amp mig then? I’m fairly confident the wiring is good
 

mar

Member
I’ve just bought myself a mig welder having never had one before I’ve bought an Rtech 250 amp single phase machine and running it off a 16amp blue socket my trouble is it keeps tripping out if I turn it up much more than half or weld for prolonged periods I’ve been trying to do continuous welds 1m long today. Firstly to mig welders take more power than stick inverters as I could weld pretty big stuff with the stick without problems on the same supply?
secondly can I run a single phase welder from a 3 phase supply perhaps in hindsight I should of bought a 3 phase machine but I wanted the ability to move it to other places on the farm not just the ones we have 3phase sockets in?
I have an Oxford 330A on single phase, I got a 32 amp blue plug installed and heavier fuses. When I put her up to the highest setting the fuse kept tripping, I had to drop her down a notch to get by, the electrician installed a heavier fuse but I didn't get to try her yet as I have nothing heavy to weld. Get your electrician out and see if he recommends putting in a 32 amp plug and heavier fuses
 

dave mountain

Member
Livestock Farmer
Yes that’s what I’m finding where I needed 100 amps with the stick I need 150. The wiring is pretty good I’d say it’s a newish 5years maybe board and is a 3phase supply having 3 phase red plug, blue 16amp and normal 13amp sockets coming off of it. I think the rcd is a C so shouldn’t be over sensitive
i think you might be meaning the MCB if its type C, if its tripping the MCB then you just need to change to 32A breaker 4mm T+E and a 32a socket. i would have thought the 16a supply would be good for at least 200A (i could max out my old 180a mig no problem on a 13a plug) but it may not be depending on your wiring. it is possible (and actually legal) that the socket is wired from the 16a breaker to the socket in 1mm T+E which would give you big power loss through heat in the cable and it would trip sooner.
 

tr250

Member
Location
Northants
i think you might be meaning the MCB if its type C, if its tripping the MCB then you just need to change to 32A breaker 4mm T+E and a 32a socket. i would have thought the 16a supply would be good for at least 200A (i could max out my old 180a mig no problem on a 13a plug) but it may not be depending on your wiring. it is possible (and actually legal) that the socket is wired from the 16a breaker to the socket in 1mm T+E which would give you big power loss through heat in the cable and it would trip sooner.
Could well be I’ll look when I go round later
 

tr250

Member
Location
Northants
i am almost certain you mean the MCB not the RCD, you dont get 16a RCDs unless its an RCBO but they are still uncommon. what size/type is the cable to the socket? is there anything else running off the same MCB?
No just a single blue plug runs off of it. The electrician put it in as a welder socket.
 

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HSENI names new farm safety champions

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Written by William Kellett from Agriland

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The Health and Safety Executive for Northern Ireland (HSENI) alongside the Farm Safety Partnership (FSP), has named new farm safety champions and commended the outstanding work on farm safety that has been carried out in the farming community in the last 20 years.

Two of these champions are Malcom Downey, retired principal inspector for the Agri/Food team in HSENI and Harry Sinclair, current chair of the Farm Safety Partnership and former president of the Ulster Farmers’ Union (UFU).

Improving farm safety is the key aim of HSENI’s and the FSP’s work and...
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