Single Phase Welders, let's get to the bottom of this

[MikeNZ]

Hi Guys,
As an Electrician, I do testing and tagging in a few places, because I can, it is pretty soul-destroying but it pays the bills.
Now, every time I test and tag a couple of places, the welders (mainly MIG and Stick) have got 15A plug-tops attached to them because the company that services the welders, state they must have
such a plug, if they are going to test and certify their work after they repair them.
So, we now have welders with the 15A plug, there are adapters using a 15A cord connector, a short length of 2.5 mm flex into a 10A plug, so that they can still use the welder.

To be fair, what is the point in using a 15A plug, when everyone knows that the only larger part of the plug is the Earth pin and that only carries Fault current, should there be an actual fault within
the welder, this in itself does not make a lot of sense.
Upon first sight of this going on, I contacted what was then EnergySafe, got no answer, I have spoken to various electrical inspectors since and it seems like no-one wants to "make a decision"
or cover their own arse over something that seems reasonably simple.

The way I see this, all single phase welders are fitted with at least a 1.5mm or 2.5mm flex on them, due to the amount of current they carry when operating, irregardless of wether they are
an inverter type or not.
If any welder was to be connected correctly to a power supply, it would need a 20A 3-pin plug, with the Phase and Neutral pins being larger than the current AS 3112 10A type, however, how many of these socket-outlets have you ever seen installed and the heavier cable feeding them?

I'd really like some guidance on this, because I have had so many arguments with workshop staff and managers over this for at least 3 years.
I suggested they should be hooked up with like a PDL 56 series connection system, that went down like a cup of cold sick, because once they go out to site, there is no means of connection there,
because the customer is not going to have stuff like this installed for possibly a once or twice job.

Can anyone please throw any light on this issue, because, I have exhausted any avenues of information.

Thanks,
Mike T.

[AlecK]

the adapter cords you describe are electrically unsafe; because they can have 15 A pf load applied when the plug is only rated 10 A..
Would be OK if they had an in-line mcb to limit the current.
Which takes care of the issues arising from carrying the welder (or whatever) around a variety of customers' sites.

As for the only difference between 10 A and 15 A plugs / sockets being the size of the earth contact;
yes that difference is obvious but it's not necessarily the only difference.

Fact is that even though the A & N pins of a 10 A rated plug are (probably) big enough to carry a higher load,
the plug has not been tested for running 15 A. If they had been tested (and passed) they would be rated 15 A.
Same for the socket - remember the current doesn't only flow in the pins of the plug; it also flows in the female contacts of the socket.
And you can't make the same simplistic assumption that the load contacts of a 15 A rated socket are identical to those of a 10 A rated socket.

The whole point of having the larger earth pin is to avoid having loads > 10 A plugged into 10A sockets.
The simplest way was to make the earth contact bigger. In fact the while range of "3112" sickest is designed to be down-wards compatible.
Eg you can plug a 10 A plug into a 30 A socket.
Other ranges use different method, eg in the 3123 Standard (most of 56 series is "3123") the difference between 16 A & 20 A is a key; the pins being identical. Yo can plug a 16 A plug into a 20 A socket, bit not the other way around.
And you can plug a 4-pin plug into a 5-pin socket.

Any action that allows excessive load to be plugged in,
be it filing down the earth pin, or using an adapter without current-limiter, or fitting a 10 A plug,
is an unsafe act - and almost certainly illegal.
Not to mention rendering fire insurance invalid.

[MikeNZ]

Hey thanks AlecK,
That has cleared up a lot of things for me.
Being a qualified welder myself, before having got into the electrical trade, I have a single phase TIG welder here at home that draws 23.8A at full noise (200A output), this had a 15A plug on it
when bought from new, 5 years ago, although the nameplate said it only would draw 14.4A, I tested it with a clamp-meter after the supply cord got too hot to touch when welding up some stainless parts
for a mate of mine.
I felt quite ripped off about this and ended up wiring it to a 32A 56 series plug/socket arrangement, as the supplier said they weren't responsible for what people do in their workshops.
So, this sort of thing seems to be based on lies and made up figures to get appliances like this under the radar.
And I suspect it isn't just me with this issue, there are possibly hundreds of welders out there that could be a fire hazard, if used to the 9th degree of their duty cycle.

Cheers,
Mike T.

[AlecK]

I expect that tally-plate rating of 14.4 A will be the max continuous load, ie at 100 % duty cycle.
The unit won't be able to draw 23.8 A continuously.

I don't believe that's valid; should be the actual max load for normal operating.
Excluding inrush /start / arc-striking currents; so equivalent to FLC for a motor.

[PawPatrol]

WorkSafe - Energy Safety did something about this situation in 2021 and issued a prohibition on use of an adaptor/supply lead that allows a higher rated plug to be adapted down to a lower rated plug without inline protection. Sign up to the updates on their website, that's how they advise of things like this.

So simple answer it has been prohibited and they cannot be used. All other arguments are irrelevant.

https://gazette.govt.nz/notice/id/2021-au1309

[Satobsat]

You also see the same thing with caravan plugs and DIY 10A adapters, without overload protection.

One other point about 15A plugs on welders is that they are often used with an extension lead, if used correctly it will be a 15A rated extension cord and quality 15A extension cords are almost always heavy duty 2.5mm ² CSA cable, thicker , tougher, sheath for harsh environments.

You would hope any experienced and reputable welder would always choose the beefier cable, or run their welder off a decent generator.

Although I have seen a crappy warehouse white, 1.0mm² CSA, extension cord used to supply a 15A welder before, which also had a an adapted earth pin. Home gamer obviously.

I'd be advising them to use a generator with a 15A outlet.

[MikeNZ]

I expect that tally-plate rating of 14.4 A will be the max continuous load, ie at 100 % duty cycle.
The unit won't be able to draw 23.8 A continuously.

Yet, that is the input current my welder is drawing, during a steady bead placement, maybe the thing is faulty, but it does good welds.
Also there is no such thing as a welder of any kind that I know of, that gets anywhere near 35-40% duty cycle, no matter what sort of
output current they profess to have in the product literature, there is always a thermal trip/internal overtemp mechanism,
that prevents the weldor ( the person using it) from damaging the welder itself due to the internal current/voltage transformation required
to generate this sort of welding current at the torch, there is no such thing as a welder with a 100% duty cycle even in the largest welding
machine you can buy.

I have since upgraded my own welder to a 32A socket-outlet/plug arrangement, just for use at home, it is fed by a 4mm flex and is protected by a
25A D curve breaker.

[MikeNZ]

WorkSafe - Energy Safety did something about this situation in 2021 and issued a prohibition on use of an adaptor/supply lead that allows a higher rated plug to be adapted down to a lower rated plug without inline protection. Sign up to the updates on their website, that's how they advise of things like this.

I totally understand that things like this should be prohibited, that is just dangerous, even them silly looking 15A - 10A (with a box with a CB in them) adapters.
But, the idea is, should places that might have a guy in their place to do some welding every now and then be required to install a 20 or 25A socket-outlet near the switchboard, it makes sense I suppose, but how many people are going to take that concept on, with the extra cost?
Yes it is downward compatible, so you can fit anything else in there, just not your caravan.
And to be fair, a lot of places I deal with do have the 2.5mm² leads, not the cheap ones that other places management give them.

What are your thoughts?
There are a lot of welders out there that probably don't comply with the Regulations and they work perfectly well, 100% of the time.
However, if someone causes a fire in the wiring of a building due to non-compliant equipment, my question is, who carries the can for that?
And I think you guys already know the answer to that.....