Another power to garage post...

[Nic Norwood]

Basically just want anyone to pick me up on anything I may have missed or planned completely wrong!

4mm2 from 32a mcb with RCD protection run from c/u to exterior, down exterior wall in conduit and under ground in cable pipe for about 10m then terminate into garage c/u.

Distributed to a 20a and 6a fuse for an A3 Radial and Lighting circuit.

 

[Rappid]

What type of cable? SWA?
What type of conduit? metal or plastic?
Are you using the RCD on the CU?

 

[Nic Norwood]

No. T&E, the cable pipe is specifically made for this I'm told. ¬.¬
20mm Black metal conduit.
And yes I will be using the RCD on the Main CU and a DP isolator on the Garage CU

Thanks for the help.

 

[Deleted member 26818]

You would be better served by placing the RCD protection at the garage CU.

 

[Nic Norwood]

Yeah I guessed that would be the case but as there's no spare ways on the non rcd side of the house CU it would be a ball ache to re-arrange.

(bearing in mind this is a favour so don't want to spend too much time there)

 

[Rappid]

What about putting the tails into a henley, then take a feed from the henley into a DP isolator then your cable to garage then RCD in garage?

 

[Nic Norwood]

Yeah, I would have done that personally, but the 'favouree' ( my brother) already has the materials and doesn't want to spend more money so I'm kinda limited!

 

[Rappid]

Looks ok to me.

 

[Nic Norwood]

Cheers mate. Just one of those situations where someone gives you un-ideal materials and situations and you start questioning what's kosher. aha.

 

[Deleted member 26818]

Would it be possible to cut down the Busbar on the RCD side, jog over the MCBs and put a longer piece of Busbar on the NON-RCD side?
I guess at the end of the day, it's between you and your Brother to decide what's more inconvenient.
The possibillity of a fault which would cause the RCD to trip, or the hassle involved with providing the RCD protection at the garage RCD.

 

[topquark]

I'd much rather have separate rcd/rcbo protection in the garage CU. If the trip goes it'll take out the lights and power in the garage which is a potential safety concern.

 

[malcolmsanford]

All the OP will have to worry about with not protecting the cable with an RCD is if the system is TT, or that T + E is buried and does not need the RCD protection.

But agree with spin and TQ it would be worth, if possible to arrange the existing CU to have it on a non RCD side if the installation method allows.

 

[Engineer54]

No. T&E, the cable pipe is specifically made for this I'm told. ¬.¬
20mm Black metal conduit.
And yes I will be using the RCD on the Main CU and a DP isolator on the Garage CU

Thanks for the help.

One thing that no-one has mentioned here yet, ....is the use of 20mm black metal conduit in a direct buried situation!! Not a very good idea at all, it could be totally corroded, or in serious need of replacement within 5 years. It is not and never has been specifically made to be used as a buried duct, that's just pure Rubbish i'm afraid!! It is only good for dry interior installations, so not even good for surface mounted exterior work!!!

Never use anything made of ferrous metal when being buried in the ground. Heavy (thick walled) PVC pipe is always going to be your best option, when being used as a protective cable duct...

So ''Don't'' use it, your brother will soon be regretting it, ...big time!!!

 

[i=p/u]

what are they like engineer 54.... they could use a tesco bag as they dont degrade for a 100 years

 

[Deleted member 26818]

Tesco bags are no use, they have holes in them.
Sainsbury's on the other hand...