What Size KVA Generator for MIG Welder

[Tony Smith]

Originally Posted by Lionelgee

The welder's specifications are:

Input Current: 16A

Originally Posted by Lionelgee

The grand plan is to get the shed hooked up to mains power - with 15 amp circuits

I see a problem here, do you?

[rob love]

I have always been surprised that so many of the welders (and other shop items like chop saws etc) require more than 15 amps yet only have 15 amp plugs on them. The threat of fire aside, it is very annoying when you are laying a nice bead of weld to have the machine suddenly shut down.

[Lionelgee]

Originally Posted by Tony Smith

I see a problem here, do you?

Hmmm 15 amp circuit and a 16 amp input. I just checked and Hayman's sell RCBO C Curve Type A 1P 16A 240V 30mA 6kA 1MOD DIN Mount
Brand Hager
Range onekombo
P/N HAGADC316T

Therefore an upgrade in the future wiring specifications from the first thought of 15 amps up to 16 amps. As I am not an electrician would this change in wire specifications cover the difference?

The blurb states: Input Power: 115-230/1/50/60
Power Factor Correction (PFC). More Welding Power, Energy and Cost savings, Generator Compatible

Would the PFC make up for the missing amp?

Kind regards
Lionel

[Tony Smith]

Originally Posted by Lionelgee

Therefore an upgrade in the future wiring specifications from the first thought of 15 amps up to 16 amps. As I am not an electrician would this change in wire specifications cover the difference?

Kind regards
Lionel

If they tell you it needs 16A to run, then make sure it gets all that and more.
Why dance around on the threshold and risk poor performance?

If the shed is not yet wired, just put in 2 20A circuits, one each end of the shed and be done with it. The labour will be exactly the same and the difference in wire price will be neglible for the few metres required.

If you can fit it in the budget now, even installing 3 phase will be cheaper at this point in time than in the future.

There may come a time when you might be expanding your workshop and be looking at a mill or lathe, that's not the time to be forced to rewire the shed because you didn't allow enough capacity.

[Lionelgee]

Hello Tony,

As previously mentioned - I am not an electrician. If fitting 15 amp circuits is one amp too few; then using my basic mathematics - would getting 20 amps circuits fitted be 4 amps too much?

Or does the welder regulate itself via some internal mechanism and only utilise 16 out of the 20 amps? With the four extra amps is there a risk of burning or overloading the welder with too many amps?

Go back to the "I am not an electrician" part...

Kind regards
Lionel

[Tony Smith]

Yes, in exactly the same way that you can plug a 2400 watt heater or a 5 watt phone charger into a regular household 10A powerpoint, the device (or "load") will only draw the current it needs.

But if it needs more current than any part of the circuit can supply (any part = supply cabling, circuit breaker/fuse, power point, plug, power lead to device), then you are going to either trip the circuit breaker or blow the fuse, or cause overheating to wires or plugs that can lead to fires.

A 20A circuit will be sufficient to allow a total of 20 Amps of current for all devices connected to it to flow through it safely, it will not "pump" 20 Amps into anything that can't handle it. In fact you could still plug in a 40watt light globe into it if you wanted to.

[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