Concrete shed supply...

[willy1984]

Hi there,

I'm planning a shed supply project in order to get my part p...

The concrete shed is going to have 3 double sockets and 4 strip lights. There is a spare way in the house CU.
The shed is roughly 50 metres along from the house CU.

Here is my plan...
From the spare way in the CU, 6mm SWA cable fixed to the garden fence (or underground) on a 40A RCBO supplying a garage consumer unit with 30mA RCD. From here, a 1mm cabled radial lighting circuit on 6A breaker and a ring circuit for the sockets using 2.5/1.5mm cable on a 30A breaker...


Does this sound any good?!?!

Willy

 

[Hawk81]

if you are fitting a 30mA rcbo in the house then there is no need to fit an rcd in the shed. You need discrimation between them.

 

[m4tty]

The socket ring will be on a 32a breaker and how have you come to 6mm have you done load calcs etc?

 

[willy1984]

I worked out that the total power of the circuits would be around 7232 watts or 31 amps...
over 50 metres it looked like a 6mm would suite best ... ?

 

[nrgmark]

Hi

Theres a cracking little volt-drop calculator on the TLC-Direct website here Voltage Drop Calculator

I personally would use a 10mm 2 core SWA fed from the consumer unit from a 40A MCB (no rcd required due to earthed armour). Earth the armour at the house consumer unit end, but NOT at the garage end.

Then use an RCD protected consumer unit in the garage and install an earth rod at the garage end to make the garage a seperate equipotential zone.


nrgmark

 

[Hawk81]

Hi

Theres a cracking little volt-drop calculator on the TLC-Direct website here Voltage Drop Calculator

I personally would use a 10mm 2 core SWA fed from the consumer unit from a 40A MCB (no rcd required due to earthed armour). Earth the armour at the house consumer unit end, but NOT at the garage end.

Then use an RCD protected consumer unit in the garage and install an earth rod at the garage end to make the garage a seperate equipotential zone.


nrgmark

why does he have to put a separate earth to the garage?

 

[nrgmark]

@Hawk81

Well yes, he could use a 10mm 3 core SWA and extend the house equipotential zone. I am just saying what I would do personally, based on the fact that the NIC guy who comes and inspects me prefers that outbuildings have their own seperate equipotential zone. But I do find that a few of them have conflicting ideas about things.


nrgmark

 

[davelerave]

it's preferable to have the rcd at the shed end-50m is a long walk back

 

[GStueyXR]

it's preferable to have the rcd at the shed end-50m is a long walk back

Deffo agree with this. Imagine the RCD tests LOL, 600 meters to run for resets

 

[m4tty]

Deffo agree with this. Imagine the RCD tests LOL, 600 meters to run for resets

Not if he's using a megger mft with Auto rcd tests

 

[willy1984]

so with the change of the rcbo at the house board, my planning sounds ok?

Thanks so much for the help! This is my first install alone!

 

[jase]

excuse my 2 pence worth, but why a 32A ring in the garage for 3 sockets? 2.5mm radial on a 20A breaker would be ok wouldnt it?

 

[Spudnik]

No reason why not, depending on load.

 

[sootyfire]

if PME sorry TN-C-S supply then you have to provide seperate earth for garage ie rod and RCD

 

[WayneL]

if PME sorry TN-C-S supply then you have to provide seperate earth for garage ie rod and RCD

No you don't

http://www.electriciansforums.net/e...ectrical-forum/15577-supply-outbuildings.html


A good diagram from GN8 at Post 15



.

 

[sootyfire]

if PME sorry TN-C-S supply then you have to provide seperate earth for garage ie rod and RCD

re yesterdays post
have contacted NIC tech help and verdict is to use rod and RCD at garage end
this is to prevent the extension of the equipotential zone and any problems bonding now or in future
and is to comply with the esqc regs which i wiil check and post back findings

 

[WayneL]

re yesterdays post
have contacted NIC tech help and verdict is to use rod and RCD at garage end
this is to prevent the extension of the equipotential zone and any problems bonding now or in future
and is to comply with the esqc regs which i wiil check and post back findings

The NIC need to read GN8 and probably the Regs while they're at it.

They also need to realise that they don't make the rules.

They are annoying when they come up with their own regulations that are in contradiction with BS7671