Oxford 180A 3ph socket

  1. Rig Pig

    Rig Pig Member

    Messages:
    3,755
    Location:
    Narrwich! U.K.
    Just about to get a 3ph welding socket put into my garage for a 180A oilcooled Oxford, anyone using one on a 16A socket or will it need a 32A?
    I don't plan on getting anything larger so a 32A is pointless if I don't need it.
     
  2. hotponyshoes Member

    Messages:
    3,399
    Location:
    Somerset. Uk
    Unless you are fitting it yourself the cost of fitting is probably going to outweigh the cost of the cable and socket by some margin so I would be tempted to just fit 32a anyway!

    Not sure if you mean 3 phase or 3 pin but if 3phase then that's 3x16a so should be plenty for a 180a welder
     
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  3. brightspark

    brightspark Member

    Messages:
    31,762
    Location:
    yarm stockton on tees
    if its 3 phase a 16 amp socket wired in 2.5mm will be ok if its single phase a 30 amp socket wired in 4.omm
     
  4. Rig Pig

    Rig Pig Member

    Messages:
    3,755
    Location:
    Narrwich! U.K.
    Cheers, it's 415V 3ph, I've got a roll of 2.5mm SWA and spare 16A MCB in the board so happy days, the welder trips the single phase 32A supply, I'm hoping the upgrade will stop this.
     
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  5. timgunn1962 Member

    Messages:
    128
    Location:
    Lancashire UK
    Could be I'm being dense, but...

    What is tripping, and when, on the single-phase supply?

    What is the breaker marked as? It may have a letter to denote the tripping curve. Usually this is a "B", but there are also "C" and "D" curves.

    If the breaker is tripping on power-up, it is likely to be because the inrush current exceeds the instantaneous tripping current of the (type B?) breaker. Going to a breaker of the same current rating, but with a different curve may solve the problem. It should be an easy change if the board is one of the bigger names and the breakers are still available.

    If it's fine on power-up, but tripping after a period of use at high current, it suggests you need a bigger supply.

    Going from 32A, 230V to 16A, 400V should actually be a reduction in the supply, not an increase if the welder only uses 2 legs of the 3-phase supply (which I am pretty sure is the case). 32A x 230V = 7360 VA, 16A x 400V = 6400 VA

    For a bit of an explanation of tripping curves:

    https://www.voltimum.co.uk/articles/selecting-right-mcb-or-rcbo
     
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  6. 8ob

    8ob Forum Supporter

    Messages:
    6,724
    Location:
    moscow on thames
    I am not sure this is correct Mr Pig but I ran five core ( included the neutral } swa to a bodge box and mounted both sized plugs for future proofing. I am glad I did because they both get regular use.

    Bob

    [​IMG]
     
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  7. brightspark

    brightspark Member

    Messages:
    31,762
    Location:
    yarm stockton on tees
    are you using them on single phase. if so are you using 2 of the cores to a 16 amp breaker and the other 2 on a 30 amp breaker ??separated or if 3 phase have you just looped the wires across to feed both if so the breaker would be either 32 amp or 16
     
  8. Rig Pig

    Rig Pig Member

    Messages:
    3,755
    Location:
    Narrwich! U.K.
    It's currently on the workshop 240v 32A ring, on start-up the in rush pop's the MCB sometimes, I will have a look and see what curve it is.
    My plan is to put a welding socket in off a spare 16A 3ph MCB and just connect 2 phases and earth in the Oxford's plug and move the jumpers to the 415V position on the machine, hopefully it will stop the annoying start-up trip, I'm also going to put a couple of 16A single phase 240V sockets in for my mig, it occasionally pops a fuse if I turn it up.
    It's strange that the 180A mig is more gentle on the supply than the 180A Oxford.
    If the 16A 3ph supply isn't big enough to supply the Oxford I could put hunt down a 32A MCB and put that in feeding a 32A socket. The incoming supply is 60A 3ph so I have a bit of grunt to play with.
     
  9. Rig Pig

    Rig Pig Member

    Messages:
    3,755
    Location:
    Narrwich! U.K.
    I like that idea.
     
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  10. 8ob

    8ob Forum Supporter

    Messages:
    6,724
    Location:
    moscow on thames
    I only mentioned the neutral Mr Pig because my Esab mig uses two phases and a neutral ,there are some weird configurations out there :dontknow:

    Bob
     
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  11. timgunn1962 Member

    Messages:
    128
    Location:
    Lancashire UK
    The initial surge is largely magnetizing the iron in the transformer. There's a lot of iron in an oil-cooled Oxford.
     
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