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robsparx

I recently picked up a job to install some power and lighting in a new small shed/workshop being built in somebody's garden.

When asking about what was going in there, the builder told me it would just be a couple of small power tools, but on further investigation the customer wants to use an arc welder out there!

I've never installed a supply for anything like this before, and am a bit unsure of the cable size etc i will need to use. In the specs in the instructions for it it says:

"mains outlet maximum duty cycle = 35A"

"recommended fuse size maximum duty cycle = 70A"

"maximum input current = 48A"

Am i right in assuming that i need to install some kind of 70A switch fuse at the mains, which would then feed an isolator and 35A commando socket to connect onto the welder?

And for the cable size, would it have to be rated at the "recommended fuse size" of 70A, or the "maximum input current" of 48A? I would go for 70A to be on the safe side, but not sure if it would need to be rated so high because after startup, it wouldnt be using so much current.

And to throw a spanner in the works, in the specs in the manual it says the mains supply lead size is 4mm, and the mains outlet size for that should be 35A. I have looked at the lead and it looks like a 4mm, but has a label on it saying that the lead is rated for 16A????

Anyone done this before??

edit: the welder is a 'thermal arc fabricator 250'
 
Last edited by a moderator:
Sounds like a mig welder, I installed one of these a couple years ago 45a type D mcb ( check your earth loop ) to 45a isolator .connect manufacturers Supplied cable
 
not just a DIY mig either the m/c is fitted with a 32a delayed fuse and they seem to recomend a 35a supply
35a might trip on heavy use ?think i would fit a 50 type c/d so you would have to go for a 63a commando sw. socket

yours benji
 
something to bear in mind is the welder is a basically a trans former and thus lowers voltage to increase current so the input supply will be much lower current than the welder output. The thing you may have problems with is your RCD protection due to inductive load and you may need a time delayed type. I have had a couple of welders and they have both been on 13A plugs (as supplied).
Maybe if in dought you should contact supplier.
Paul
 
Interesting question.
My Brother has a welder of some sort, which I have to wire in his new garage. I cant remember for sure, but I think it says it's rated at 32amps. Its on a 13amp plug at the minute, which just means he cant whack it up to maximum.

I was going to have a look at the manual, and was hoping to use a 32amp mcb and commando plug.

Anyone with practical experience would be helpfull.
 
cheers guys, just trying to work out what cable to take over to the new workshop. I'm thinking a 16mm to a new CU in the workshop, and have the welder on a 45A mcb.

the only thing is this sticker on the mains lead of the welder saying it is rated at 16A :confused:

this seems to contradict what it says in the manual type c/d

would there be such a thing as a 45A type c/d time delayed rcbo???

Also in the details it tells me 'supply watts at max output = 9450W'

So i guess this would mean that the absolute MAXIMUM amount of current that the machine could pull is about 40A?

that would mean a 45A mcb should be ok, but i'm still confused about this 'recommended fuse size' of 70A, unless this means the internal fuse in the welder itself

referring to the rec. fuse size it says

' motor starter fuses or thermal circuit breakers are recommended for this application. australian standard as3000 permits the rating of the fuse or thermal circuit breaker protecting the circuit conductors, to be double the outlet current rating for any circuit used exclusively for an electric arc welder. check local requirements for your situation in this regard'

sorry to go on and on :(
 
Last edited by a moderator:
Just had a look at the manual online, and it says supply fuse should be 32amp. Dunno about the supplied cable, if its 4mm it should be good for 32amp though.
 

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