Wiring for 25a input

[brightspark]

This thread is about runnig a welder though and not a cooker. So 32a and 4mm cable

why mention the cooker then I was giving an example of types of loadings that u mentioned

 

[rikrobson]

I didnt bring the cooker up

 

[Shaunw]

Thanks for all the replies, Ive got it now, makes a lot more sense! The length of cable will be roughly 15m from the fuse box, would you up the size to 6mm or would 4mm be suffice?

 

[WorkshopChris]

Personally I would go 6mm.

 

[daedalusminos]

There are many aspects to consider when sizing cables...cable current handling capability, ambient temperature, acceptable volt drop, installation type run length etc

Use a reliable calculator if in doubt:-

https://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

So for 25A (5.8kW) this suggests a minimum of 2.5mm2 over 15m, however since you're installing a 32A socket then you would want to rate it for 32A which would push it up to 4mm2 minimum.

However, I've just given examples for a basic installation, you need to read the page linked above to calculate correctly for your installation.

Jonathan

 

[rikrobson]

15m will put a voltage drop enought to warrant 6mm cable

 

[bwservices]

, however since you're installing a 32A socket then you would want to rate it for 32A which would push it up to 4mm2 minimum

You dont,its the opposite way .
just because its a 32a socket youre using,you dont have to rate the cable and fuse to 32a.if its 25a you want to draw from it,then its logical to rate the cable and fuse to 25a

 

[rtbcomp]

IMHO is someone buys the house later and sees a 32 A socket he may fit a 32 A MCB and draw 32A. If you fit a 32 A socket make the cabling capable of supplying 32A constantly. He may have an intermittent welder now, but he may have a compressor plus a plasma cutter at a later date.

 

[brightspark]

IMHO is someone buys the house later and sees a 32 A socket he may fit a 32 A MCB and draw 32A. If you fit a 32 A socket make the cabling capable of supplying 32A constantly. He may have an intermittent welder now, but he may have a compressor plus a plasma cutter at a later date.

that would be the responsibility of the new buyer if he were changing the breaker to know what he is doing and why . a lot of people fit larger showers and just up rate thee breakers and not the cable as they haven't a clue and should leave well alone or get someone in that does know

 

[rtbcomp]

^^ true, but some people need protecting from themselves.

 

[Mee]

I understand belt and braces etc but at what lengths of cabling do you hit 4 or 6 mm. Let alone question of price of cable. Just interested.

I would always go oversize just to be on the safe side and think of future use, any workshop wired for a welder will use other loads and these have to be factored in, lighting, sockets, additional feeds for future machinery, and obviously the kettle and fridge to make the coffee.

true, but some people need protecting from themselves.

You mean like a former neighbour of mine who wired his workshop up with whatever bit of free wire he could get from a skip, then wondered why his wiring melted and set fire to his workshop, fortunately he was in it at the time and another neighbour had a fire extinguisher handy.

 

[daedalusminos]

You dont,its the opposite way .
just because its a 32a socket youre using,you dont have to rate the cable and fuse to 32a.if its 25a you want to draw from it,then its logical to rate the cable and fuse to 25a

That wasn't really the point of my post, I was highlighting to the OP that there are many more factors than just length and current to determining the correct cable size. But now you mention it, and considering it'd cost an extra £15 or so (assuming T&E) to upgrade this to 32A during installation, for me it's a no-brainer.

Incidentally, if the OP does go with a 25A breaker then it may be wise to go for a type C if it's supplying a welder.