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UK mains supply question

I have bought a TIG welder that will run off UK 240 volt single phase 50 hertz AC supply, but on full power can draw up to 50 amps. I want to wire this off the house incoming mains distribution board, to a spur in my worksshop, about 30 feet away. The mains supply from the road is on a 100 amp fuse to the meter. The meter then feeds straight to a fuse switch with an 80 amp fuse in it. If I can get an extra pair of tails into the outlest of this switch fuse i was going to run armoured cable to a 60 amp switch fuse in the workshop, with the welder hard wired into that. Can anyone see a problem with this? I live in the sticks, and although the mains is fused

100 amp the incoming armoured cable form the pole looks quite thin...

What core size armoured do I need to be looking at? BTW, a pic of the welder load plate is at ftp://ftp.chriswilson.tv/mig/mig.jpg

Thanks.

Reply to
Chris
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Without going through the full voltage drop and diversity calculations which you should be able to find in the wiring regs, I would estimate that you'll need 10mm or 16mm conductors (which is probably quite a bit fatter than your incoming mains supply which is intended to handle domestic draws, not the industrial type of draw you are talking of). Given that, I strongly suggest that this should be surveyed and installed by a qualified electrician.

This is particularly so now as rules in the UK have changed, and you are not allowed to do your own electrical wiring any more (or if you do it must be checked and certified by a "competent person" as defined by the law).

In this particular case, I would suggest that you either:

a) Get a qualified electrician to do it.

b) Get the books and do the calculations properly to determine if this is viable given your incoming supply and only do it if so, and then get it checked by a qualified sparks (preferably get one to check your proposal b4 doing the work).

Reply to
David C. Partridge

But are you sure you would ever want to use it at full power?

Alan

Reply to
Alan Holmes

Oh, and 50 amps is rather a lot, are you sure it pulls 50amps or is it rated at max 50amps ?

Reply to
Marky

50 A is not a lot for a large TIG welder. These also have an ATROCIOUS power factor, so they generally have a huge phase angle correction capacitor bank in them. My Lincoln Square-Wave TIG 300 (at the upper end of the size range) supposedly draws 67 A of leading current when idling, due to the huge phase correction bank. The power factor gets better in the middle of the range. I have it on a 70 A breaker right now, that is the smallest one that holds on.

If that 100 Amp supply is for your entire house, as well as the shop, you are getting close to the limit, I'd think. You might have a problem with tripping the main service entry breaker if too much gear is running in the house when you use the welder. If you can arrange that all the major appliances are kept off when you use the welder, you can probably get away with it. I have a 200 A 240 V single-phase service at my house.

Jon

Reply to
Jon Elson

Thanks Jon, now installed and working up to 150 amps off a 60 amp fused switch, with dedicated wiring back to the supply meter tails. I would rarely want to pull more current than that, if so the wife wil have to read by candlight for an hour!! :) Happy New Year.

Reply to
Chris

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