I don't know if anyone on here can help but a colleague has acquired a three phase 200A Miller tig welder. The question is re. the supply cabling.

There are three wires, one red and two black, in a steel trunking. I'm guessing the three wires are the three phases and the steel trunking acts as the earth. Can anyone confirm or deny this or give us any pointers.

I'm a bit reluctant to 'give it a go' on the current () info so any help would be most welcome.

Thanks in advance,

Mike

I have connected up one of these. Inside the machine the wires are marked L1,L2 and L3. The colours have no significance I can think of. If I were connecting it I would trace them first.

Take the cover off as above, there should be a strapping diagram as it can probably do single, two and three phase.

Are you sure its 3 phase? Red is usually live, and black is usually neg. Our 3 phase MIG welders have 4 cables in armoured cable,

T1 Live
T2 Live
T3 Live
Negative

And the armour in the cable is earthed.

theprisoner is correct, the lives are usually labelled 1, 2, and 3, but are usually all black. Its POSSIBLE they have replaced a black numbered cable with a red blank cable.

Have you got any photos of where the wires join INSIDE the welder, and I will be able to help you out, or a model number so I can pull up a diagram?

FYI, 3 phases are coloured:

PHASE OLD NEW
1 Red Brown
2 Yellow Black
3 Blue Grey
Neg Black Blue

Hope this helps!