garage cu advise please No main power switch

[Yam man]

hi newbie ere so go easy on me. We are getting new lazy spa hot tub and it's going to be semi permanent fitted into our outbuilding in a wetroom separated from my workshop.We have been advised to have new mini consumer unit fitted into our loft space fed from 12m max of 10mm t&e from unused mcb 40amp protected by 80amp 30ma rcd in main c/u. Then from the newly fitted unit with 63amp 30ma rcd using the 6 amp mcb for 3 light fittings and the 16 amp mcb to run 2.5 t&e through conduit in wall and supply 3x double switch sockets. There will be 1400w heater on most of cold days whilst I'm in working and the 2.3kw hot tub always running although once heated doesn't use as much. Then if I have compressor on that circuit and 2 cordless tool battery's on charge and music also laptop is used in there off mains power for car diagnostics upgrades reference etc (learnt my lesson when battery's depleted in middle of diagnostics repairs) This type of major full load wouldn't happen all time constantly but like to think ahead for future purposes and rather overthink and ask then regret it later. Sorry for the story but I want to make sure this all sound correct. It is a family members friend who will do the work. We have no main switch to turn mains power off how will we get this done? Thanks for any help advise.

 

[telectrix]

that's a poor design. several things wrong with it. too tired to go any further tonight. be able to help tomorrow.
first thing we need to know ids what type of earthing the house has. a pic. of you CU and cut-out/meter would help.

 

[Octopus]

I would get a proper spark poor 2 to quite

 

[Rpa07]

I would get a proper spark poor 2 to quite

Someone else is tired I think!

 

[Spoon]

Welcome to the forum mate.

new lazy spa hot tub and it's going to be semi permanent fitted into our outbuilding in a wetroom

Is the outhouse attached to your house?

We have been advised to have...

Who advised this layout?

 

[Octopus]

Someone else is tired I think!

And then predictive text comes in to play

 

[telectrix]

several things wrong with the OP's proposed install.

1.RCDs in series. bad design.

2.CPC in the 10mm is not suitable for a bonding conductor. 10mm 3 core SWA would be more appropriate

Then how is the distribution cable to be installed.. underground or what?

 

[Yam man]

hi thanks for replies yes house is attached to outbuilding but the outbuilding is accessed through fire stairs out back or through door in loft space. will upload pics of cu etc after work. plan was to run 10mm t&e from main unit through floorboards of 1st floor straight up the corner of unused chimney breast in cupboard to loft space at 10m to new cu mounted on brick wall. then through clay pipe holed into wall with the 2.5mm t&e to 1st socket then along roof line taking 2 more double sockets. the lighting cable would run along roof line. there is no weather factor as all cable are always inside. 1st pic is main unit meter etc 2nd is new garage consumer unit and last 1 is main consumer unit. any help advise thanks again.

 

[Des 56]

Do you have a earth rod for this installation?
You appear to have a time delayed 100m/amp Rcd as the main switch

Depending on the sub main cable,its installation method, the need for any earth bonding,it may be possible to feed the cable off the 40 amp mcb from that side of the board ( if you intend using the consumer unit shown)

 

[Yam man]

hi Des 56 not sure what you mean by earth rod my sparx never mentioned that. but just basic google search would suggest i dont have 1 and need to install 1 as i think my house is still earthed via the lead pipes. does that sound correct? always had problem with engineers who want to visually inspect earth and never could. landlord doesn't do nothing for us at all. were would earth rod be? visible anyway? thanks for help. the time delayed 100m/amp rcd as main switch if i turn this off is board shut off or would it still be live?
telectrix can i ask what you mean with bad design with the rcd in series? im far from electrician so go easy. if i use the 10mm swa 3 core could i run that up the outside of the building and into outbuilding? would i need any other cover conduit or? thanks again

 

[Yam man]

i live in pure concrete area no soft ground if that makes difference for earth rod?

 

[Des 56]

There are a few different means of earthing a installation
The picture does not show the use of a suppliers earth terminal,if that is the case it may be a TT system, earthing the system is obtained via a copper clad rod into the ground

Because these systems usually have high impedance readings,a time delay 100m/amp rcd is used for protection of the whole of the installation.
Then a 30 m/amp Rcd for circuits requiring more sensitive protection(usually the sockets)

The cable to the rod and the rod connection itself should be visible to be inspected,its sometimes found in a earth pit or boxed near a outside wall
If it does not exist,it needs sorting,along with any earth bonding to services,and before any addition or alteration is even considered

 

[Yam man]

 

[Yam man]

i have earth cables all over our home on water pipes and on the main gas pipe into property but cant find any box or cables outside. dont know pic helps identify anything? do i need busbar covers?

 

[Yam man]

if i move the unused 40amp mcb to the right side of cu would my 1st proposal of running it be ok? i dont have any softer ground its solid upto 6ft down ive just had layed new waste pipes and manhole cover so as to earth rod i have no clue as to where or how to put it