(UK context) How can a domestic Mig Welder be 150A, and work fine on a 13A fused, single phase domestic mains electricity supply?

Question

(UK context) How can a domestic Mig Welder be 150A, and work fine on a 13A fused, single phase domestic mains electricity supply?

In: 17

Answer 1

Because welders are very low voltage.

With electricity it is possible to “exchange” voltage for current or vice versa using a transformer.

This is simply because Power In = Power Out, since you can’t make power from nothing, the power that goes in one end of a transformer has to be the same that comes out the other (neglecting losses), and electric power is Voltage x Current.

So if you have a MIG welder running at 150A at 10V that would be 1500 Watts of power, so if the output of the transformer in the welder is 10V and 150A, the input side would have to be exact same power, just at a different voltage, namely 240V. And at that voltage, you only need 6.25 amps to generate the same amount of power, so even though the welder might be running at 150A, the current leaving the outlet is only 6.25A and therefore won’t trip your fuse or breaker