Sub main for garage 80 meters away

[Scott89]

Hi guys iv been asked to put a sub main in 80 meters away!
It will need to have
1 x 32amp with 8sockets on
3 x 10amp with heater on each mcb
1 x 6amp with 8 lights on

Please give me your thoughts on cable size thanks guys

 

[Megavolt]

Sorry but what are your thoughts. What calcs have you done

 

[D Skelton]

Look in BS 7671, all you need to know is in there. Work out your design current, apply correction factors, select appropriate overcurrent and earth fault protection, select appropriate size cable, confirm adequate size CPC (if not rodding), confirm voltage drop is within permitted values, if not, upsize until it is.

 

[Richard Burns]

That is going to be a hefty cable with those heaters on it.
I think you will find your design current will be overridden by the volt drop requirements for the lights.

 

[Darkwood]

Hi Scott think your getting the theme here we don't spend 4yrs in college to give out all the calcs to any Tom, Dick or Harry..... as others have suggested you need to show us your calcs and we will be happy to help, your info given is lacking vital parts to even attempt a calc refer to your notes on cable calcs supply us with all the info and ask where you are getting stuck and help will be here but not as in you OP suggests.... do all this for me please because I either can't or can't be bothered.

 

[Scott89]

Ok I understand where you guys are coming from. My thoughts are my load is going to be 70amps and I was thinking of putting a 25mill armoured 3core cable because of volt drop for lighting ect, I haven't done a proper calcs yet, i was just seeing if anyone had any advice. So looks like ill do my calc when I get home

 

[Darkwood]

I assume a little diversity can be applied as your heating is accounted for and unless your telling us otherwise I doubt the sockets will be loaded 32amps.... also yes do calcs first although your drip feeding us info we now know its a swa .... bt is it buried ?

 

[Scott89]

Thanks yes it will be buried in ducting and they only putting a computer in there all the other sockets will hardly be used

 

[Darkwood]

Now you've been given a few tips ... do the calcs and show us your thoughts when you get time... might seem im been harsh but its best way to learn how to do it yourself if we simply got the info and give you an answer then you will always depend on others in similar situations and never really get a full grasp of it. .....80m is a good distance and at 80amps if you used this in calcs you'll surprise yourself how much larger the cable is required due to volts drop although I assume 1ph? with your random guess of 25mm .... you see now we lack a lot of info'