Garden shed cable size

[clematis432]

Hi, I,m running a supply to my neighbour,s new garage and would appreciate advice on cable size. It will be 3 core SWA running underground. The max load will be around 8A and that only for small periods(power tools) other than that only lighting,and total run will be about 30mts from house DB. I advised him to get 4mm but now think 2.5mm would do. I,m ex maintenance and retired so am very rusty regarding design calcs.
Sorry to ask further, but if he decides to take his supply from ring main to avoid approx 15mt run under floor boards will same cable size(2.5mm) be adequate if I spur it via FCU
Thanks

 

[LankyWill]

what does the regs say mate? Im not getting paid to design your install?

 

[clematis432]

You want paid ? Thanks for your help mate.

what does the regs say mate? Im not getting paid to design your install?

 

[telectrix]

download cable calc from coopersoft to your smartphone.

 

[Octopus]

Hum...are you looking for a cheap design or a proper design?

 

[clematis432]

Hum...are you looking for a cheap design or a proper design?

Proper design please, I,m battling a bit with Coopersoft calculator but thanks Telectrix

 

[Spoon]

What is the earthing system of your neighbour's house?
Does it have RCD protection?
What breaker size are you thinking of using? Or fuse if coming off a FCU?

Who is doing the install?
Do they have proper equipment to fill in the cert?

 

[LankyWill]

run it in bellwire and save yourself some cash!

 

[clematis432]

What is the earthing system of your neighbour's house?
Does it have RCD protection?
What breaker size are you thinking of using? Or fuse if coming off a FCU?

Who is doing the install?
Do they have proper equipment to fill in the cert?

TNS/Yes/B20/13A/Me/Do you need to certify in Scotland ?
Lanky Will trying hard for attention
Is it too much to ask for advice on this forum, to help an ex leccie who is a bit rusty with design ?
Not really asking for much, and attention seeking Lanky willy wants paid as well !

 

[Spoon]

Is it too much to ask for advice on this forum, to help an ex leccie who is a bit rusty with design ?

We do like to help people out on this forum mate. We just like to make sure we have all the info first, and whoever is going it will not harm themselves doing the job.
How are you running the armour?
What are you thinking of putting in the shed (like a new CU)?

 

[clematis432]

I,ve given most of the relevant info Spoon, I,ve already mentioned the cable is going underground and the expected load of the garage. Disappointed with some replies though think I,ll just go forget it now. It was not a complex thing I asked, the protection side of it was not an issue just wanted simple yes or no to 3core 2.5mm SWA.

 

[GMES]

I,ve given most of the relevant info Spoon, I,ve already mentioned the cable is going underground and the expected load of the garage. Disappointed with some replies though think I,ll just go forget it now. It was not a complex thing I asked, the protection side of it was not an issue just wanted simple yes or no to 3core 2.5mm SWA.

The Members are sometimes hesitant to give out a step by step guide of how to carry out an installation, it may seem like they are having a pop but they're just being weary.
If you look at the bit of your post that I have highlighted, this is what causes the issue, because if it isn't complicated then it shouldn't need explaining and please don't take that the wrong way I am merely trying to show you why it causes a bit of friction, But having said that can we all keep it civil and sensible please.

 

[davesparks]

TNS/Yes/B20/13A/Me/Do you need to certify in Scotland ?
Lanky Will trying hard for attention
Is it too much to ask for advice on this forum, to help an ex leccie who is a bit rusty with design ?
Not really asking for much, and attention seeking Lanky willy wants paid as well !

Yes you do need to certify the work according to the wiring regulations using an electrical installation certificate, otherwise your work will not be compliant with bs7671 and then you will more than likely not be covered by your insurance.
What you don't have to deal with is the part P notification nonsense we have on this side of hadrians wall.

As far as the job goes, personally I would not connect it to the ring circuit as it has potential to cause trouble if a fault in the shed takes out the rcd and/or mcb covering the ring.
A seperate way in the CU with a 20A mcb (or fuse if at all possible) and rcd protection fitted at the shed end would be my preferred method.

For that distance I would be inclined towards a 4mm cable as it will reduce volt drop and allow a bit of tolerance if they wish to add a bit more load later.

 

[Spoon]

Sounds like a RCD is already on the house CU dave. If fitting one in the shed the OP will have to apply discrimination.

Sorry dave, that statement is more info for the OP.

 

[Octopus]

I,ve given most of the relevant info Spoon, I,ve already mentioned the cable is going underground and the expected load of the garage. Disappointed with some replies though think I,ll just go forget it now. It was not a complex thing I asked, the protection side of it was not an issue just wanted simple yes or no to 3core 2.5mm SWA.

Hum..... an interesting response..... a bit on the arrogant side IMHO. Me thinks help may be evaporating now.