my garage, being separate from the house, is supplied by armoured cable to it's own consumer unit. The sockets are protected by a 13A MCB which only trips if I forget to switch off my fan heater and halogen heater before welding.

This has happned to me several times...

However I am safe in the knowledge that the MCB will trip before I overload the cable. You should be fine.

As said, granted you can fit the wires into a standard 13A plug it will be fine. As the fuse is there for protection.

If you have availiable space in your diss board it would be better running some heavier cable from a 20Amp MCB to a blue 16Amp socket specially for your welder.

Will