What Size KVA Generator for MIG Welder

[Grant Bowker]

Think of the circuit size as "maximum capacity". More capacity doesn't hurt, too little can be a problem (just like my paycheck). You can plug a tiny incandesant (eg. 40W) light bulb into the same circuit that will run a toaster (eg. 1500W), each will run without problem.
Taken to extremes, more capacity can be a problem. There is a bit more cost due to cost of wire. At least in North America, there can be different shape plugs and outlets for different capacities that may limit what can be plugged into the outlet. If a short should develop, the larger wire and breaker means there could be a lot of power (creates more heat and shock hazard) flowing in places you don't want it (including through you).
In general I agree with the idea if having some surplus capacity on every circuit in case you should ever buy something that needs a bit more push. Just don't go crazy....


On edit, Tony posted as I was still typing (slowly). Funny that we both chose the 40W bulb as an example.

[Lionelgee]

Hello Grant and Tony,

Thank you for your patience and explanations. They are greatly appreciated.

Kind regards
Lionel

[Paul Singleton]

In addition to Grant’s post, when I was working my employer purchased a plasma cutter for use in the shop. An electrician was called to install a second 230 volt 50 amp circuit to feed the new plasma cutter. When checking the specifications the plasma cutter was rated at 230 volts and 30 amps, but had a 50 amp plug on it. The electrician was concerned because if the plasma cutter rated at 30 amps was powered by a 50 amp circuit there was a risk of the plasma cutter catching on fire if it developed a short as it may not trip the circuit breaker. On further reading of the manual it was found that the manufacturer used a 50 amp plug for convenience to the user so it could plug into a standard welder receptacle, but the machine itself had an internal 30 amp fuse on the power supply. The electrician had not heard of this before and thought it was unusual.

Paul

[rob love]

Another thing that is commonly done here is that when you wire a shop, although you may be putting in 15 amp circuits (which will use 14 gauge wire) you use 12 gauge wire. That way, if (and usually more like when) the time comes that you need to increase the capacity of a circuit, you just have to change the receptacle and breaker. If your wiring is inside the walls you can leave it alone.

[Grant Bowker]

I believe household voltage in Australia is 230V 50Hz like much of Europe rather than 110V 60Hz like Canada/USA so the wire gauge required may be different (same wattage, smaller wire gauge required with higher voltage, again - no harm in more capacity than the minimum).

[chris vickery]

It is the inrush current that trips the breaker.
If you device is hovering around 16A a 15A breaker may or may not hold it. A better choice is to use a 20A circuit.
As it is not being used continuously at the 16A level, not really a concern.
Now that being said, as in the above post, placing a device such as the plasma cutter on a 50A circuit is just plain dangerous. Upsizing the breaker for a device meant to run 30A is a fire waiting to happen or at the minimum, potential damage to occur in your equipment during an overload situation