Question for electrical engineers?

Tracer:

What's the duty cycle of the welder when running flat tack on 230 V? It will be <50%, hence the plug is smaller than the max current draw.

To meet the "Electrically Safe" or "Electrically Unsafe" definition as per the Electricity Safety Regulation (Regulation 5)

Putting a 15A plug on a device which lists the maximum current of 27A would pose a risk of wiring catching fire, significant damage etc.. This would clearly fall in to the category of Electrically Unsafe.

As far as using duty cycle of 50%, unless there is some built in device to limit the duty cycle it would be assumed that the duty cycle is 100%

Ensuring that the circuit is protected by a suitably rated circuit breaker would not solve the problem either, as a 15A circuit breaker does not trip at 15A, there is a trip curve, the higher the current the quicker it will trip, you may find running 27A it may take somewhere in the vicinity of 500seconds, that is around 8min 20 seconds. For this 8mins and 20 seconds 27amps is coursing thru your standard 2.5mm power circuit cable, 2.5mm is simply not rated to pass 27A so it turns in to a big heater, plastic starts melting, the wood in your walls that the cable travels through starts to get hot, you have all the makings for a house fire.

Even if you don't reach the point of starting a fire the wiring in this circuit has now become damaged and unsafe.

It has been brought to the attention (in the past couple of years) of the testing and tagging companies that visit businesses to do the electrical testing and tagging that Welders are a problem, they should check the nameplate specifications and if the plug rating is less than the maximum current draw on the nameplate then it's a fail.

My advice:-

Don't listen to anyone here who is not an electrician.

(Yes I am an electrician)

Do not put a 15A plug on your 27A welder, it is electrically unsafe, regardless of you having a modern fuse board with circuit breakers fitted

Typically the only circuit in a house capable of supplying 27A safely would be your oven.

Ropata

gregmcc