Planning garage sub-main project

[Liam151807]

Hi all, 2nd year apprentice.

I'm looking to take a supply out to my garage, which is detached, from the DB at the front of the house (2 bed terraced, built 1978~)

The length of run is about 30m (having to go through either loft or under floorboards).

Intend to have a 20A radial and a 6A lighting circuit so am I right in thinking I'd allow 66% diversity for lighting and 50% for the power circuit as it's over 10A? So 13.96A total demand?

Thanks

 

[mainline]

Ok so lots to think about haha.

Realistically I'm leaning towards fitting a new board at the house with RCBOs. Then to supply the garage DB, a 40A MCB. Am I right in thinking I'd need RCD protection for this sole MCB?

No not as long as the criteria is met for disconnection /cable sizing /bonding etc

You need to know the type of earthing you have and if the garage door is actually extraneous or there is a likelihood of having anything extraneous that may require bonding.

 

[Liam151807]

No not as long as the criteria is met for disconnection /cable sizing /bonding etc

You need to know the type of earthing you have and if the garage door is actually extraneous or there is a likelihood of having anything extraneous that may require bonding.

I think I'll get some pics later with the board cover off for you all to have a look at to build the picture further.

I can't think that there is anything that will need bonding in the garage tbh, unless you count the metal board itself?

 

[mainline]

Post #24 Said garage door ?

There is still not enough information to give a definitive answer.

 

[Liam151807]

Post #24 Said garage door ?

There is still not enough information to give a definitive answer.

Only thing that is metal I can think of. It's connected to a wooden frame attached to the wall so no chance of it becoming live I'd say

 

[loz2754]

So far, all the advice offered has been on the technical side of things.
Has anyone pointed out that a new circuit, and/or a new consumer unit has to notified to local authority building control before work commences? (Or that the work be carried out by a registered competent installer.)

 

[goasis]

The right hand side of your board with the lighting MCBs isn't RCD protected and the blank will be a spare way- so subject to a decent Ze you could simply fit an additional matching MCB for the new SWA, but it will have to be glanded properly, possibly into a small metal enclosure to ensure the armour is earthed. EDIT= Ah I've just seen your post stating T&E for the first part of the run, so the SWA can be glanded into a weatherproof enclosure with an earthing nut and lead to the CPCs.

If you need this much guidance I'm not sure you should be taking the work on

 

[MJPD29]

Ok so lots to think about haha.

Realistically I'm leaning towards fitting a new board at the house with RCBOs. Then to supply the garage DB, a 40A MCB. Am I right in thinking I'd need RCD protection for this sole MCB?

If you’re using twin and earth depending on your route maybe, then no rcd in garage. If swa straight to board no rcd protection in house just in garage board. In all honesty this is really basic stuff that you should know.