Attaching 13A plug on 20A appliance safety

[azengineering]

Hello everyone, I hope this is the correct forum to post this. I am an amateur tinkerer with no formal training in electrical engineering and I’m just looking for some information and advice on how to safely wire up and use some appliances.

I have recently bought a hobbyist TIG inverter welder (single phase) to learn basic DIY welding techniques. It has been supplied with power supply wiring protruding from the back for the unit but with no plug attached to the other end of the bare wires. I was of the belief that I could attach a standard UK rectangular 3 pronged plug with a 13A fuse and just plug it in to the domestic outlet socket in my garage and use the welder with no problems at low power. Doing a bit of research it looks like the input current to the welder is stated in the handbook as 20.7A so I am concerned to just attach the 13A plug.

I do not have 32A sockets in the garage just what I assume is standard domestic duty rectangular 3 pronged outlets. My questions are, is it safe to attach the 13A fuse and plug to the welder and plug it in to domestic socket? If there is no other load on the circuit and I use only the welder at low output current will this be okay? Is the first thing to go the 13A fuse in the plug I installed or will the circuit breaker trip first, will the wiring behind the walls overheat before the fuse in the plug blows? As the property is rented I can’t really fit a 32A outlet in the garage so I’m just wondering what my options are and what solutions other people have come up with to safely overcome similar problems.

Thank you very much for your time it’s greatly appreciated.

Ali.

 

[littlespark]

No. It’s not safe to do as you suggest. The 13A fuse would blow even at a low setting on the welder.
Your only option is to ask the landlord if you can put in a circuit from the CU to the garage just for the welder.
And have an electrician put it in for you. Specialist equipment requires specialist knowledge

 

[Pete999]

No. It’s not safe to do as you suggest. The 13A fuse would blow even at a low setting on the welder.
Your only option is to ask the landlord if you can put in a circuit from the CU to the garage just for the welder.
And have an electrician put it in for you. Specialist equipment requires specialist knowledge

What he said^^^^^^^^^^^^^^^^^^^^^^^^^^^

 

[JOURNEYMAN]

What they said ^^^^^^^^^^^^^^

 

[Pete999]

Welding is NOT a domestic pastime is it? come common sense prevails, most of the time it does anyway.

 

[Toneyz]

What whoever said!

 

[Pete999]

What whoever said!

Well I said what he said.

 

[Toneyz]

Well I said what he said.

Yes you said it well Pete, let's move on.

 

[Pete999]

Yes you said it well Pete, let's move on.

Not up to me Ant

 

[Deleted member 26818]

If the 13A plug will fit the cable, then there should be no problem.
It’s only when you start welding thicker material that you’ll find the fuse blowing.

 

[Ian1981]

I believe that the maximum flex size for a 13amp plug top is 1.5mm

 

[westward10]

Any chance you can post a pic of the rating plate?

 

[Deleted member 26818]

I purchased a Clarke mig welder 155T in 1994.
Supposed to be on a 20A supply, but it has always been on a 13A plug.
Not once have I had to replace the fuse.
Most of the time, it’s used on an extension lead, as the lead with the machine is too short.

 

[azengineering]

Cheers guys, that’s sort of what I thought, I think I’ll look into using a different lower powered unit. I’ve tried to attach a picture of the information plate on the back of the welder, hopefully the picture has worked.

What exactly about it would be unsafe, if the 13A fuse would be the first thing to go wouldn’t this ensure that the garage wiring and everything else would be intact?

Ali

 

[westward10]

I1eff=14A is your effective load current so this is excessive for connection to a 13A plug top.

 

[Toneyz]

I1eff=14A is your effective load current so this is excessive for connection to a 13A plug top.

To be honest, that's probably why a 13A moulded plug has not come attached.

 

[Pete999]

If the 13A plug will fit the cable, then there should be no problem.
It’s only when you start welding thicker material that you’ll find the fuse blowing.

If something is

To be honest, that's probably why a 13A moulded plug has not come attached.

anthony is correct I think, most appliances come with a moulded plug attached, when something arrives without a plug it could be the manufacturers are trying to tell you, don't plug this equipment into a 13 A socket imo

 

[Risteard]

If the 13A plug will fit the cable, then there should be no problem.
It’s only when you start welding thicker material that you’ll find the fuse blowing.

Instead of rating all of my posts "dumb" in retaliation, perhaps you should accept that your post actually is dumb.

 

[Taylortwocities]

this is excessive for connection to a 13A plug top.

Isn't the connection made to the bottom of the plug? The top is usually just a safety cover feature.

 

[westward10]

Plug bottom with top

 

[Lucien Nunes]

What exactly about it would be unsafe, if the 13A fuse would be the first thing to go wouldn’t this ensure that the garage wiring and everything else would be intact?

Marginal overloads do not usually blow the fuse, but experience shows that they can stress the contacts and connections in sockets etc. Prolonged load just over 13A is a known cause of burnt electrical accessories. The fuse is primarily there to protect against fault conditions, not incorrect usage, although it acts as a backstop to avoid wiring overheating if the plug is overloaded. In the case of the welder, because the load is intermittent, damage is unlikely, but you can't assume that modern accessories made down to a price with withstand even 13A for long.

As it is an inverter welder, you might find that the current is comfortably within 13A on lower output settings. Plugging it into an energy monitor that has a current display mode might confirm, if you can keep the current steady enough. But if the flex is 2.5 sqmm, it may not be possible to make a safe termination into a 13A plug anyway.

 

[westward10]

I am pretty sure BS1363 restricts the maximum size of cord to 1.5 so I would not suggest the OP attempts connecting a 2.5

 

[Lucien Nunes]

Indeed - if the current were within 13A I would terminate it to a 16A and use a jumper.

 

[Deleted member 26818]

Instead of rating all of my posts "dumb" in retaliation, perhaps you should accept that your post actually is dumb.

Strange how I’ve posted the same advice on the Screwfix Forum and the IET Forum, yet it’s only you who thinks it dumb?
Like, I’ve said, I’ve been using the same 13A plug with the same fuse for over 20 years on my mig welder.
Unlike a tig welder, the mig also has a wire feed motor.

 

[telectrix]

as spin says. should be OK.try the bugger on a 13A plug. worst thing is the 13A fuse will blow.

 

[Risteard]

as spin says. should be OK.try the bugger on a 13A plug. worst thing is the 13A fuse will blow.

The worst that will happen is that it won't blow with a small overload of long duration.

 

[Deleted member 26818]

The worst that will happen is that it won't blow with a small overload of long duration.

Sorry, but that is rubbish.
The very nature of welding, means that there is no long duration.

 

[Risteard]

Sorry, but that is rubbish.
The very nature of welding, means that there is no long duration.

No point trying to dress it up - it's very poor advice to give that this could be an appropriate way of connecting it up. It's wholly inappropriate. There's a reason it doesn't have a BS 1363 plug (aka plug top) on it.

 

[Risteard]

Strange how I’ve posted the same advice on the Screwfix Forum

LOL. And you think that enhances your argument? Let's be honest - that forum is largely inhabited by the clueless and the clinically insane.

 

[Deleted member 26818]

No point trying to dress it up - it's very poor advice to give that this could be an appropriate way of connecting it up. It's wholly inappropriate. There's a reason it doesn't have a BS 1363 plug (aka plug top) on it.

I and many others disagree.
This is not an oven or tumble dryer that will be on for hours at a time, often at full load.
This is something that while it may be on for a long periods, will rarely (if ever) be at full load.
The only constant load will be for the fan and perhaps a neon to indicate the machine is on.
There will only be high load for short durations, the magnitude of the load depending on the thickness of the material being welded.
The duration of the load is restricted to the length of the filler rods being used and the duty cycle, which on higher loads can be as little as 30%.

 

[Deleted member 26818]

LOL. And you think that enhances your argument? Let's be honest - that forum is largely inhabited by the clueless and the clinically insane.

You are not the only member there.

 

[Deleted member 26818]

You are not the only member there.

True though.

 

[Risteard]

the IET Forum

"LoL - Diversity in action - or possible small overloads of long duration, depending on your viewpoint

Regards

OMS"

So the small overloads of long duration scenario has actually been raised to you before, ergo I am not the only one to ever question the practice.

 

[Deleted member 26818]

No, that was just a comment made by OMS, not a response to anyone in particular, and not even a factual statement.

 

['mr2'gd4u]

Alright agree to disagree, not worth an argument is it.

 

[alasdairp]

I believe that the maximum flex size for a 13amp plug top is 1.5mm

where is that stated? Manufacturer data sheet or some BSI or similar document? Thanks.

 

[alasdairp]

I have used a similar welder (with c. 2.5 mm^2 stranded wire) with an old strong MK 13A plug on it since the mid-1970s in a variety of places, thin and thick welding rods, and sockets. It has always worked and neever blown the (correct 13A) fuse in the plug. The high-current loads do not last for long. I would just do that - BUT - I would also weld for say 10 minutes and the unplug it and feel the plug legs to see how warm they have got. You need a solid plug and a quality socket or they could easily overheat.

 

[Risteard]

where is that stated? Manufacturer data sheet or some BSI or similar document? Thanks.

BS 1363

 

[LeeH]

If the 13A plug will fit the cable, then there should be no problem.
It’s only when you start welding thicker material that you’ll find the fuse blowing.

Give me enough time and incentive, I’d just about squeeze a 4mm2 into a plug top.

It’s not the rule of thumb I would recommend personally.

 

[tudore]

I also have a welder that can draw up to 30Amps. As it was only required for thin (vehicle) welding I fitted a 13A plug, and have used it without a problem for several years. It is always used on a long extension so there will be lower voltage and subsequently higher current than a direct feed.
I have been a qualified spark for 10 years, but prior to that I had experience in electronics / medical sciences / tinkering for 2 decades. I also did a welding course 30 years ago, which is something you probably haven't considered. Provided you don't try welding angle iron, I doubt you'll have a problem with the electrical supply. But please do remember to clear the area of any combustible material, and preferably have a fire extinguisher (CO2) handy, or at very least an old towel in a bucket of water!

 

[Deleted member 26818]

Powder extinguishers make a right mess.

 

[tudore]

Powder extinguishers make a right mess.

Exactly why I only mentioned the alternatives, but it is probably a good idea to state they are a bad idea. I don't believe that there is a risk of the wiring catching fire: the socket will be fed by 2.5mm, and the lead is 4mm, so a 13A fuse will blow well before either of these melts. The precautions against fire were for the benefit of a first-time welder, who may be so concerned about the fuse blowing that they forget the second main danger is from sparks setting fire to the place. (The main danger being electrocution by simultaneous contact with work-piece and feed).