UK mains supply question

C

Chris

Guest
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.
 
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).

David
"Chris" <chris@chriswilson.tv> wrote in message
news:121wgkrvqlycn.6jc0kd4lkvxq$.dlg@40tude.net...
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.
Click to expand...
 
"Chris" <chris@chriswilson.tv> wrote in message
news:121wgkrvqlycn.6jc0kd4lkvxq$.dlg@40tude.net...
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.
Click to expand...
But are you sure you would ever want to use it at full power?

Alan
 
"Alan Holmes" <alan.holmes@virgin.net> wrote in message
news:agCpf.39898$7p5.1916@newsfe4-win.ntli.net...
"Chris" <chris@chriswilson.tv> wrote in message
news:121wgkrvqlycn.6jc0kd4lkvxq$.dlg@40tude.net...
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.

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

Alan
Click to expand...
Oh, and 50 amps is rather a lot, are you sure it pulls 50amps or is it rated
at max 50amps ?
 
Marky wrote:

"Alan Holmes" <alan.holmes@virgin.net> wrote in message
news:agCpf.39898$7p5.1916@newsfe4-win.ntli.net...


"Chris" <chris@chriswilson.tv> wrote in message
news:121wgkrvqlycn.6jc0kd4lkvxq$.dlg@40tude.net...


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.


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

Alan



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




50 A is not a lot for a large TIG welder. These also have an ATROCIOUS
Click to expand...
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
 
On Fri, 30 Dec 2005 17:19:22 -0600, Jon Elson wrote:

Marky wrote:

"Alan Holmes" <alan.holmes@virgin.net> wrote in message
news:agCpf.39898$7p5.1916@newsfe4-win.ntli.net...


"Chris" <chris@chriswilson.tv> wrote in message
news:121wgkrvqlycn.6jc0kd4lkvxq$.dlg@40tude.net...


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.


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

Alan



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




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
Click to expand...

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.
 
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