New welder on the way

[Dev]

I've taken the plunge and ordered a SWP 220. I see from the specs it's fused at 16 amps.

My ring mains supply in the garage is 2.5 twin and earth cable with a 32 amp mcb.

I'm just wondering if I need to run a dedicated heavier cable or would it be safe to connect a 16 amp socket to the existing cabling.

Anyone know if the swp comes with a plug attached and of which type so I can get the wiring done in advance of it arriving?

 

[bigtip]

if the welder is fitted with a 16a 'industrial' type plug it won't have a fuse in it. you could fit a 16a socket from a fused spur but i think the biggest fuse that you can fit in the spur is a 13a so it will be safe but you won't technically have a 16a supply so you might as well put a normal 13a plug on the welder in that case.
ideal solution: no need for a heavier cable but run separate circuit in 2.5mm2 or even 1.5mm2 cable (subject to routing of cable etc) supplied by a 16a mcb.

having said all that, french regs don't require fuses in plugs and a 2.5mm2 cable supplied through a 20a mcb would allow a big or small appliance to be plugged in and it is in theory safe, so it should be safe to drop the mcb of your garage ring main down to 20a and fit the 16a plug/socket but someone else, maybe brightspark will know if that meets uk regs or not.

 

[Dev]

I do have a 16a mcb, 16a draw won't burn out 2.5 then?

Something like this on the wall http://www.ebay.co.uk/itm/NEW-240V-..._Supplies_ET&hash=item3371090c29#ht_600wt_689 back to the 16a MCB for protection?

 

[brightspark]

I do have a 16a mcb, 16a draw won't burn out 2.5 then?

Something like this on the wall http://www.ebay.co.uk/itm/NEW-240V-..._Supplies_ET&hash=item3371090c29#ht_600wt_689 back to the 16a MCB for protection?

2,5mm will be well fine on a 16 amp mcb as said u can go up to a 20amp on a radial supply that socket will be ok to use . it doesnt need an isolator switch near it as the plug and socket IS the isolator

 

[W.olly]

So this is the same as what i wanted to do from my old cooker point...i think, i thought i could fit a 16amp MCB in the workshop fed from the old cooker point then to the blue 3 pin plug. I havnt measured the cooker feed cable yet but i am sure it will atleast 2.5.
Only thing is though is the consumer has a 30amp fuse, spose i should fit a RCD then

Sorry to hijack Dev but i am in the same situation as you for when i get my new welder soon.

 

[bigtip]

w.olly, your cooker point should be 6mm2 cable, any circuit fused at 30 amps needs to be at least 4mm2 cable unless its a ring. if it's not then change the fuse/mcb.

just to clarify, a 2.5mm2 'ring main' type circuit fused at 30 or 32a is technically using 5mm2 as each socket is supplied from both directions with 2.5 making effectively a 5mm cable.
2.5 is just easier to work with than thicker cable sizes for these long and sometimes convoluted cable runs but the ring main's days may be numbered.

 

[madkayaker]

Rings don't quite work that way as the current flowers through the lowest resistance path. So would only flow through both in the electrical mid point. I would advise against running a welder from a cooker point (unless you want the welder in the kitchen!) as the additional cable will add to the earth loop resistance and lower the fault current that is required to operate your fuse or MCB and may not disconnect under fault.

 

[Dev]

I have seen a cooker socket where it was a spur off the ring mains. I did wonder at the time what was the point of the heavier cable when it went back to std mains but I guess that explains it.

 

[bigtip]

Kayaker, the current will flow more through the path of least resistance, but in the case of a household ring circuit the flow from both sides of the ring would be the same pretty much. like resistors in parallel, the current is inversely proportional but the difference in resistance of the cable is not much on runs that are regulated by room size.
don't wanna get too technical but the earth loop impedance would be 'improved' by the bigger cable size of a cooker circuit and wouldn't affect the operation of your mcb anyway as that is an overcurrent protection device.

 

[Dev]

Fingers crossed I get the call today to say its arrived.