Electrical question-max “temporary” current on 2.5 T&E?

[mart]

I need to use the arc welder just long enough to weld a nut on a gate hinge (round a friend’s place) using maybe 1.6 rods to keep the current down (max 60 seconds). The welder is 30amp and normally fitted with 30amp round pin plug when used at home in my garage , with a hard wired 30 amp supply.

My intension is to put a 3 pin plug on with a “big fuse” just for this 1 minute blast. The weakest point in the whole circuit will then be the wiring in the ring main. I know it’s not normal procedure, but will it be ok just for 1 minute on low amps, or will I melt the insulation on his wiring?

 

[madkayaker]

bodging the job will damage the wiring and is a fire risk. Just because the welder is 30amp full whack it will be much much less at 60amp. use a decent extension lead keep all fuses proper size and see how you get on

 

[brightspark]

I need to use the arc welder just long enough to weld a nut on a gate hinge (round a friend’s place) using maybe 1.6 rods to keep the current down (max 60 seconds). The welder is 30amp and normally fitted with 30amp round pin plug when used at home in my garage , with a hard wired 30 amp supply.

My intension is to put a 3 pin plug on with a “big fuse” just for this 1 minute blast. The weakest point in the whole circuit will then be the wiring in the ring main. I know it’s not normal procedure, but will it be ok just for 1 minute on low amps, or will I melt the insulation on his wiring?

just what ive head u understand i know someone with a 180amp pickhill oilcooled welder who has a 20 amp fuse wire soldered across the holder in the plug and it welds 2.5mm rods regular at 120 amps and has done for the last 30 years years .if u plug in the ring and the socket u use isnt just spured off it will carry 30 amp no problem

 

[tlovatt]

just what ive head u understand i know someone with a 180amp pickhill oilcooled welder who has a 20 amp fuse wire soldered across the holder in the plug and it welds 2.5mm rods regular at 120 amps and has done for the last 30 years years .if u plug in the ring and the socket u use isnt just spured off it will carry 30 amp no problem

To weld at 120A you do not need 30A, a 13A socket with a standad 13A fuse should be good for welding upto around 150A without a problem.

No need for any daft wiring attempts at all.

 

[brightspark]

To weld at 120A you do not need 30A, a 13A socket with a standad 13A fuse should be good for welding upto around 150A without a problem.

No need for any daft wiring attempts at all.

i dont know what welder u have that will run on a 13 amp fuse at 150 amp output .my oilcooled pulls 35amp input current set on 120 amp output using 2.5mm rods .even aircooled 150amp wont run on a 13 amp fuse for more than a half a minute

 

[neilarmo]

Standard procedure used to be to use the plug socket next to the electric cooker for any heavy jobs, as it was wired to the same supply as the cooker and was 20 amp plus fuse.

Inverters are the best thing for these type of jobs, find another mate with one or just give the hinge top a good pillocking with the hammer to burr it over.

Nothing will stop the cordless grinder brigade anyway.

 

[rich r]

As others have said above, I think you misunderstand the relationship between the current drawn from the mains and the current used by the welding arc. On most ac arc welders, 13A from the mains equates to about 110-150A welding current (depending on whether it's an efficient inverter or a simple buzzbox).

With 1.6mm rods you're probably drawing only 6A from the mains to get 50A welding current - so a 13A plug and extension will be more than adequate. You can probably use 2.5mm rods if you wanted to (though if it's a buzzbox, the initial strike current may exceed 13A)

 

[PTvor]

You shouldn't melt the wiring in the ring main, provided it's properly done and is in good condition, because the ring main should be fused at the fuse box or consumer unit with, (IIRC, a 30 amp wired fuse or 32A MCB). Obviously the purpose of the MCB or fuse is to stop the wiring of the ring main being damaged under any conditions.

If you only want to do 30 seconds of welding with a 1.6mm or 2mm rod at no more than 60A, why not try it with a 13A fuse? Anyway, I think the problem you'll have is the inrush current when the welder is switched on rather than the sustained current draw when welding with rods 2.5mm and less. A welder sitting there connected to the mains and ready to weld should take only a small current.

Better still if you can borrow a little buzz box which is usually run off a 13A plug, to do it.

 

[Robotstar5]

Standard procedure used to be to use the plug socket next to the electric cooker for any heavy jobs, as it was wired to the same supply as the cooker and was 20 amp plus fuse.

Still limited by the 13A fuse in the plugtop though.

 

[madkayaker]

the only approved way to get greater than 13 amp without wiring into the cooker outlet point (which is a really bad idea and has been covered on here many many times) is with properly designed circuit and bs4343 outlets (16/32)

you can get a 20 amp double pole switch but would need hard wiring into

 

[tlovatt]

I have an inverter type MMA welder and it will run happily at 150A using 3.2mm rods without blowing a fuse (other than ocasionally!) A relative has an old oil filled Oxford MMA welder and I have used this at 100A without problem for extended periods via a 13A plug with a 13A fuse fitted

 

[brightspark]

I have an inverter type MMA welder and it will run happily at 150A using 3.2mm rods without blowing a fuse (other than ocasionally!) A relative has an old oil filled Oxford MMA welder and I have used this at 100A without problem for extended periods via a 13A plug with a 13A fuse fitted

it must have been a super 13 amp fuse an oxford oilcooled is made by pickhill the same as mine and input current draw @ 100 amp output is 40 amp inrush current on striking up and 32 amp constant when laying a rod

 

[tlovatt]

A 13A fuse should not blow for any current under 20A and will; normally withstand a 30A current for a minute or so (although you do thermally stress them). the current figures for your welder seem rather high, ignoring tx losses you have an on arc voltage of circa 80V - I would expect it be be more in the range of 30V to 45V