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cable size for 300amp welder

  • 03-11-2014 3:46pm
    #1
    enricoh
    Registered Users, Registered Users 2 Posts: 5,082 ✭✭✭


    lads i just bought a 300 amp single phase oil cooled welder and want to run a cable to a shed for it 30m away from my fuse box. what size cable would i need for it? i've an unused hydrodare 1" pipe that i'd rod it through to save on getting swa. want to put a cut off switch on it too. i've lights n a few sockets out to shed already but cable out is too light for this beast!
    i'd doubt if i'd ever use the highest setting so would only ever use 3/4 of the available power
    the welder came with a 32amp big blue plug on it if that helps at all?


Comments

  • #2
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    enricoh wrote: »
    lads i just bought a 300 amp single phase oil cooled welder and want to run a cable to a shed for it 30m away from my fuse box. what size cable would i need for it? i've an unused hydrodare 1" pipe that i'd rod it through to save on getting swa. want to put a cut off switch on it too. i've lights n a few sockets out to shed already but cable out is too light for this beast!
    i'd doubt if i'd ever use the highest setting so would only ever use 3/4 of the available power
    the welder came with a 32amp big blue plug on it if that helps at all?

    The 300 amps that you refer to is on the secondary side of the welder.
    This will be a far larger current than on the primary side.
    What you need to do is see what the welder is rated at (in terms of kVA).

    If the 32A single phase plug on the welder has been sized correctly then the welder will draw no more than 32A from the mains. The smallest cable size that can feed a 32A socket is a 6mm^2. As your cable run is long this may push the cable size to at least 10mm^2, perhaps even larger. This will depend on other factors. This will not fit into a 1" hydrodare!

    An SWA (steel Wired Armour) cable is generally best for this type of application.

    Remember an undersized cable has a number of disadvantages, apart from the safety implications it will result in less power output from the welder.


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