Mig welding and cable run.

[Hanson]

Some advise or views would be appreciated.

My supply is 100 amp single phase.

I purchased my property 3 years ago or so, the owner prior to the couple I purchased it from had installed a single external 32 amp socket near to the kitchen back door.

The cable to this socket is easy enough to trace, it runs externally from the 32amp socket in 25mm conduit vertically just over 2,5m into the property then under floorboards, ( no conduit ), where I can trace the cable to a 32amp MCB directly from the CU.

EDIT This socket is a blue 32amp socket.

The cable size is 6mm, the total cable run length from the socket to the CU is about 13m.

I now have to embark on learning a new skill, Mig Welding.

My front garden is 50m L x 26m W.

I have to do some running repairs and add to an existing metal palisade fencing some of which is at the furthest reach of the garden.

Having done some extensive reading and viewing I should think a simple 150 amp inverter Mig will do.

I have been able to get hold of 53mt of 3 Core HO7RNF 2.5mm² cable.

My intention is to attach a 32 amp plug to one end of the cable, a single 32 amp socket to the other end, remove any existing fused plug top attached to a new Mig and fit a 32 amp plug instead.

Will I be able to use a 150 amp rated Mig off the existing 32 amp socket in conjunction with the 50 odd metres of 3 Core HO7RNF 2.5mm² cable I have?

 

[westward10]

32A sockets, assuming it is one of the blue ones are not suitable for installation in dwellings.

 

[Hanson]

32A sockets, assuming it is one of the blue ones are not suitable for installation in dwellings.

Yes but realised my error, its blue and 2.5m runs externally in conduit near to the kitchen back door into the property under floor boards to the CU.

 

[Fazz711]

150A MIGs I have used in the past have had 13A plugs.
Only when going to 160-180 have they needed 16A plugs.
I have seen 180A ones on 13A plugs but as soon as you get near the top end of the Amps scale it will blow the 13A fuse.
Check your welder as it will say what the input amps are a d then you can decide which plug is appropriate.

 

[Hanson]

150A MIGs I have used in the past have had 13A plugs.
Only when going to 160-180 have they needed 16A plugs.
I have seen 180A ones on 13A plugs but as soon as you get near the top end of the Amps scale it will blow the 13A fuse.
Check your welder as it will say what the input amps are a d then you can decide which plug is appropriate.

Thanks for the reply.

Almost all the 150amp or lower Mig welders I have seen come with 13a plug tops but it seems to me so light weight and the plug tops are likely to get very hot even if welder is used in short bursts.

But the manufactures are the experts and they fit these 13a plug tops

So the question remains using 50m of 3 Core HO7RNF 2.5mm² cable, essentially a very long extension lead, am I ok to run a 150amp Mig without the risk of tripping MCBs or blowing the main 100amp fuse using the existing external 32 amp socket?

 

[Fazz711]

Thanks for the reply.

Almost all the 150amp or lower Mig welders I have seen come with 13a plug tops but it seems to me so light weight and the plug tops are likely to get very hot even if welder is used in short bursts.

But the manufactures are the experts and they fit these 13a plug tops

So the question remains using 50m of 3 Core HO7RNF 2.5mm² cable, essentially a very long extension lead, am I ok to run a 150amp Mig without the risk of tripping MCBs or blowing the main 100amp fuse using the existing external 32 amp socket?

No way it will trip 32A MCB or the 100A fuse presuming the 32A is covered by 32A MCB

 

[Hanson]

No way it will trip 32A MCB or the 100A fuse presuming the 32A is covered by 32A MCB

Thank you, do you have any advise on using such a long extension lead?

I mean would it be ok to so?

 

[Fazz711]

Thank you, do you have any advise on using such a long extension lead?

I mean would it be ok to so?

Not sure I don't have regs for volt drop with me so if someone can advise on that.
50 M is quite a long way so may have to go up a size in cable

 

[pc1966]

For any outdoor socket you should have RCD protection, that way you still should have shock protection & ADS.

For 32A and 50m extension a quick check is saying 10mm, for 13A it is suggesting 4mm. Generally that won't fit a typical 13A plug/socket but a metal-clad socket and IP68 gland, plus 32A plug, could make up such a lead.

Tested of course...

 

[Hanson]

For any outdoor socket you should have RCD protection, that way you still should have shock protection & ADS.

For 32A and 50m extension a quick check is saying 10mm, for 13A it is suggesting 4mm. Generally that won't fit a typical 13A plug/socket but a metal-clad socket and IP68 gland, plus 32A plug, could make up such a lead.

Tested of course...

Thank you, BIB that's easy enough to resolve, have the existing 32amp socket changed to one with RCD protection.

Not making sense of your last part.

Are you saying the 50m extension cable needs to be 10mm in size instead of the 3 Core HO7RNF 2.5mm² cable I intended to use or are you saying the existing 6mm cable from the CU to the new 32amp RCD socket should be run in 10mm T&E cable?

 

[pc1966]

To meet 5% voltage drop at 32A you need 10mm, for a more realistic 13A load it is 4mm.

There are three sizing requirements for cables:

• Current carrying capacity (CCC) to avoid overheating
• Voltage drop (VD) so end loads are operating within expected tolerance
• Earth fault impedance (Zs) to make sure Automatic disconnection of Supply (ADS) is met sufficiently fast depending on the circuit protection (fuse/MCB, use of RCD)

 

[Hanson]

To meet 5% voltage drop at 32A you need 10mm, for a more realistic 13A load it is 4mm.

There are three sizing requirements for cables:

• Current carrying capacity (CCC) to avoid overheating
• Voltage drop (VD) so end loads are operating within expected tolerance
• Earth fault impedance (Zs) to make sure Automatic disconnection of Supply (ADS) is met sufficiently fast depending on the circuit protection (fuse/MCB, use of RCD)

Thank you

As the new Mig will be rated up to 150amp, if the existing external socket is changed to a 16 amp RCD protected socket and the existing MCB is changed to a 16amp rating would this help me when it comes to the size and length of the extension lead?

 

[westward10]

It is not permitted to have unshuttered socket outlets in a dwelling both 16 and 32A fall into this category.
Does the welder come with a fitted 13A plug?

 

[Hanson]

It is not permitted to have unshuttered socket outlets in a dwelling both 16 and 32A fall into this category.
Does the welder come with a fitted 13A plug?

My error in my original post which I corrected, the existing 32 amp socket is not in the property but externally fitted.

 

[pc1966]

It is not permitted to have unshuttered socket outlets in a dwelling both 16 and 32A fall into this category.

Would that also apply to those outlets with an interlocked switch? I.e. where the contacts cannot be live without the appropriate plug being inserted to allow the switch to be turned to the on position.

 

[Rockingit]

It is not permitted to have unshuttered socket outlets in a dwelling both 16 and 32A fall into this category.

If fitted with interlocks then no problem. It's also back to that classic argument of where does a 'dwelling' end - I've both 16 & 32's in my workshop, at home.

 

[Hanson]

It is not permitted to have unshuttered socket outlets in a dwelling both 16 and 32A fall into this category.
Does the welder come with a fitted 13A plug?

I hadn't answered your question in my previous reply. the new Mig will come fitted with a 13a plug top.

Most I believe do.

 

[Hanson]

If fitted with interlocks then no problem. It's also back to that classic argument of where does a 'dwelling' end - I've both 16 & 32's in my workshop, at home.

My existing external 32amp socket will be replaced with one with RCD protection.

As @westward 10 says it is not permissible to fit an unshutterd socket in a dwelling, I didn't think it possible to buy an unshuttered version for domestic use for inside a property, I've never seen one.

Does the 16 or 32amp external type require an interlock switch?

I have no garage or work shed at the moment but working, using a very large, exposed concrete patio area.

 

[pc1966]

If you are using a welder with 13A plug then a 13A extension lead is practical. You could make one with 2.5mm which is about as much that will squees in to decent 13A plugs & in-line sockets and a quick check says it is OK for VD at 40m length.

Or maybe better, put in a couple of fixed weatherproof sockets around the area so you are never more than 15m from one when you need it! That way 6mm cable could be used, but it has to be UV proof so not T&E !!! (Unless in conduit/trunking)

 

[westward10]

2.5 is beyond the specification for a 13A plug.

 

[Hanson]

If you are using a welder with 13A plug then a 13A extension lead is practical. You could make one with 2.5mm which is about as much that will squees in to decent 13A plugs & in-line sockets and a quick check says it is OK for VD at 40m length.

Or maybe better, put in a couple of fixed weatherproof sockets around the area so you are never more than 15m from one when you need it! That way 6mm cable could be used, but it has to be UV proof so not T&E !!! (Unless in conduit/trunking)

In almost all other circumstances that would be a way forward but not in this instance, for me anyway.

I sought further advice from others and there seems to be a consensus.

As the Mig will have very little use and that use spread over a couple of months while learning how to weld before getting on in earnest and repairing and as the Mig will be used at the furthest end of the garden, (50m) for a short time only my intention is to do below.

Remove the 13a plug top supplied with the Mig and replace with a 16a plug.

Make up 50m of 3 Core HO7RNF 2.5mm² as an extension cable with 16a socket and plug at either end.

Replace the existing mounted 16a external socket with one that has RCD protection.

Incidentally both people I spoke to independently were appalled the original installer of the 16a socket relied solely on a 32a MCB for any kind of personal protection and why they didn't fit a RCBO, I'm grateful you mentioned the RCD.

They did say just for now stick to the 32a mcb but when done with all welding to swap it for a 16a mcb.

The 6mm cable that supplies the 16a socket from the CU would have been better run in 10mm but for my temporary welding needs "should" be ok.

Fortunately most of the welding repairs and metal fence add ons will be within a 25m radius of the 16a socket, still a long extension cable but better by half.

 

[Hanson]

2.5 is beyond the specification for a 13A plug.

It is, I have in the past been guilty of squeezing 2.5 cable in to a plug top but not clever.

Repeating what I have been told and how I understood, manufactures of most electrical items they sell in the UK must fit a plug.

Clearly with items such as Mig welders they wish they hadn't to but UK law obliges them.

 

[nicebutdim]

Incidentally both people I spoke to independently were appalled the original installer of the 16a socket relied solely on a 32a MCB for any kind of personal protection and why they didn't fit a RCBO, I'm grateful you mentioned the RCD.

They did say just for now stick to the 32a mcb but when done with all welding to swap it for a 16a mcb.

Were either of the people you sought alternative views from an electrician?

The reason I ask is it seems highly unlikely they'd be appalled by the original installation's lack of RCD protection, then advise that you go ahead and use the socket with overcurrent protection at twice its rating.

I don't mean to cause offence but, given that you're now pretty much at the plan originally posted, it seems as though you've more interest in seeking affirmation of your own ideas than sound advice.

 

[Hanson]

Were either of the people you sought alternative views from an electrician?

The reason I ask is it seems highly unlikely they'd be appalled by the original installation's lack of RCD protection, then advise that you go ahead and use the socket with overcurrent protection at twice its rating.

I don't mean to cause offence but, given that you're now pretty much at the plan originally posted, it seems as though you've more interest in seeking affirmation of your own ideas than sound advice.

Yes both of them.

The advice, opinion for RCD protection for the 16A socket came from this thread and I mentioned it to both electricians, they didn't say not to, both agreed it a must.

Not seems, I am still seeking sound advise, opinions, further affirmation, are you saying I was told wrong and why?

 

[davesparks]

Will I be able to use a 150 amp rated Mig off the existing 32 amp socket in conjunction with the 50 odd metres of 3 Core HO7RNF 2.5mm² cable I have?

No, the minimum cable size for a 32A supply would be 4mm. 2.5mm is too small to safely be used for 32A.

 

[davesparks]

It is not permitted to have unshuttered socket outlets in a dwelling both 16 and 32A fall into this category.
Does the welder come with a fitted 13A plug?

I thought the regulation said they must not be used for household purposes, not that they cannot be installed in a dwelling or domestic installation?

 

[westward10]

I thought the regulation said they must not be used for household purposes, not that they cannot be installed in a dwelling or domestic installation?

 

[Hanson]

No, the minimum cable size for a 32A supply would be 4mm. 2.5mm is too small to safely be used for 32A.

Thank you.

 

[davesparks]

View attachment 115963

Exactly, household and similar use.

A welder requiring a 32A supply isn't household use regardless of whether it's a domestic installation.

 

[Rockingit]

Exactly, household and similar use.

A welder requiring a 32A supply isn't household use regardless of whether it's a domestic installation.

This is an interesting issue. I agree with you however I took this to task with a scam inspector some years ago and we agreed to disagree that the definition of ‘dwelling’ was the area served by the designated earthing system. On that basis my house has 16, 32 and (1ph > 3) 63/3 outlets for everyday household use - so I call BS on the whole thing!