Wire choice advice to feed workshop please.

[Graham Orm]

Up to now my workshop has been fed by a heavy extension lead. On the theory that I only use one machine and the lights at once, I've been OK so far.
I'm about to buy some armoured cable what size? How many core? The workshop is 5 metres from the house, the cable will have to go up the house wall and travel round the outside of the house to the front. I already have a duct running the length of the garden for the cable.
I have a table saw, thicknesser router table etc. I've just added an extraction system with 2vac's that run at the same time as the machines, which has prompted this post.
I also use an arc welder and a MIG occasionally.

 

[No skills]

It may help the resident sparks if you can work out what sort of ampage you will be pulling when using your bigger tools plus the dust extraction and lights at the same time. Do you have any big machines or is it all 13a plug stuff?

I have a 32a supply via 6mm armoured, haven't managed to overload it yet but all my tools are 13a or less.

 

[AJB Temple]

Calculate the entire cable length and add a couple of metres for fixing. If your workshop is only 5m from the house then you extra cost for having plenty of spare capacity in the cable will not be enormous. I would make provision for a 13amp ring, lights of course and a couple of 16amp sockets as well (in case you want ta big bandsaw or whatever).

You will struggle to pull even 4mm 3 core armoured through ducting if you ahem any sharp bends. I would probably upscale to 10mm. The cost differential from 6mm to 10mm will be about £30 over a fifty metre run. Much better too big than too small.

Whoever is signing off your Part P will tell you what he / she is happy with.

 

[Graham Orm]

It may help the resident sparks if you can work out what sort of ampage you will be pulling when using your bigger tools plus the dust extraction and lights at the same time. Do you have any big machines or is it all 13a plug stuff?

I have a 32a supply via 6mm armoured, haven't managed to overload it yet but all my tools are 13a or less.

It's all 13a stuff. I imagine the heaviest load will be the lights and the welder or table saw/extraction/lights.

 

[n0legs]

I think A 40 amp supply would be ample for your needs.
But what is the loading of the 2 vacs and the machine you would be using with them?
What size welders do you have?
You could use a 4mm but I would use a 6mm 3 core xlpe SWA cable.
I prefer 3 core so one core can be used as an "earth" (CPC- Circuit Protective Conductor). I've written here before about my attitude to providing the "earth" via the armours.
Do any other services exist in the shed/workshop and does the workshop contain structural steel work or is it substantially constructed from steel?
The reason I ask is because depending on the type of supply you have in the house depends whether you can "transport the earth". Some area electricity boards/DNO's don't like the transportation of the earth to outbuildings on certain services.

Give me some more info and I'll try and advise a little better.
Also total length of the cable run is important.

 

[Graham Orm]

I think A 40 amp supply would be ample for your needs.
But what is the loading of the 2 vacs and the machine you would be using with them?
What size welders do you have?
You could use a 4mm but I would use a 6mm 3 core xlpe SWA cable.
I prefer 3 core so one core can be used as an "earth" (CPC- Circuit Protective Conductor). I've written here before about my attitude to providing the "earth" via the armours.
Do any other services exist in the shed/workshop and does the workshop contain structural steel work or is it substantially constructed from steel?
The reason I ask is because depending on the type of supply you have in the house depends whether you can "transport the earth". Some area electricity boards/DNO's don't like the transportation of the earth to outbuildings on certain services.

Give me some more info and I'll try and advise a little better.
Also total length of the cable run is important.

35 metres run
both vacs 1400w each
welder 130amp
Workshop is concrete panels with steel roof with no other services

 

[n0legs]

35 metres run
both vacs 1400w each
welder 130amp
Workshop is concrete panels with steel roof with no other services

Use 6mm xlpe swa 3 core, you could go to 10mm if you wanted some future proofing, but for a 40 amp supply as I said earlier 6mm will be ample.
In the workshop I would use a 32 amp ring circuit for sockets, it would most likely only be a very short ring circuit, but there's plenty of capacity in it for a machine and the 2 vacs to be used at the same time.
Leave the remaining capacity for a 6 amp lighting circuit.

Using the links below tell me which type of supply you have-

http://www.flameport.com/electric/suppl ... supply.cs4
http://www.flameport.com/electric/suppl ... supply.cs4
http://www.flameport.com/electric/suppl ... supply.cs4

Once you've done that I should be able to tell if you can safely take the "earth" from the house out to the workshop or not.
Is the steel roof fitted to steel rafters and purlins? Is it like a Compton Sectional Garage construction?