Wiring Garage and Shed

[meenax]

Hi. I wonder if someone can advise.

I want to take a 4mm SWA from my house, outside some 6m, to the brick built garage. Here, I want to put a 40A/30mA RCD MK weatherproof consumer unit. I want to replace the 16A and 6A MCBs (that come with CU) to a 16A and 20A MCB. Is this ok? Will the 40A/30mA input cater for the 16A/32A MCBs?

I want to have one 16A radial for the garage for two sets of double sockets plus a switched spur for lights (2 x 58W flourescents + 1 outside courtesy light). From the 20A MCB I want to take another 5m SWA through the garage outside to the shed. There, I want to have 2 sets of double socket plus switched spur for lights (max two 58W flourescents).

Maximum usage of garage is possibly 13A and a garage dor opener (6A). For the shed possibly up to 2 x 13A appliances (washing machine and tumble dryer). Plus maybe a 400W hedge trimmer!

What cable types I should use inside the garage and sheds? 4.0mm or 2.5mm T&E? Or flex?

Will this setup do. Thanks.

p.s. The house CU will be a 16A or 32A MCB non-RCD

 

[luminaire]

Who will be doing the work?

 

[ColJack]

ok, for a start your maths doesn't work out..

you want to run a 16A supply from the house, to feed a total (possible) load of 40A...

from that you wan to run a 16/20A feed to the shed where you say you will have 2 13A appliances... so that's 26A when both are on..?

oh and don't put the WM and TD into a double socket, make it 2 single sockets.. it'll stop the socket melting...

would buried cable be ref method 1? if so then 4mm² 2 core armour only takes 38A...

 

[meenax]

Who will be doing the work?

a qualified electrician will be doing the "wiring" up. I want to save myself some money by carrying out the "labour" work.

 

[meenax]

ok, for a start your maths doesn't work out..

agreed.

you want to run a 16A supply from the house, to feed a total (possible) load of 40A...

So would I need a 40A MCB from house CU?

from that you wan to run a 16/20A feed to the shed where you say you will have 2 13A appliances... so that's 26A when both are on..?

This is the bit I am not sure about. electrician advises I only need one of the 16A that will run from CU doing all the garage then from there continue to shed and place another socket there. Admittedly I decided on 2x13A applicances after I spoke to him. I am not sure why he was avoiding a ring and preferred radial. Any benefits here?

I cannot see myself using more than 2x13A in shed and 1x13A in garage

oh and don't put the WM and TD into a double socket, make it 2 single sockets.. it'll stop the socket melting...

Ok, thanks. I will have them on separate double sockets

would buried cable be ref method 1? if so then 4mm² 2 core armour only takes 38A...

cable is bot buried yet. I intend to run it along house and side wall into garage. I do not need to bury it. 4mm or 6mm is not decided. I will make 6mm if that is what would be reqd.

 

[ban-all-sheds]

a qualified electrician will be doing the "wiring" up. I want to save myself some money by carrying out the "labour" work.

Then ask him all these questions.

He is the one who has to put his name to it, so he has to be the one to make all these design decisions.

You cannot go off and ask random questions on a forum like this, install various MCBs and cables, and expect him to certify it. In fact, I'm amazed that he is even letting you do anything like that. Fair enough if he's happy for you to labour for him, to save a few quid, but he is in charge, and you should do exactly what he tells you, and only what he tells you.

 

[meenax]

a qualified electrician will be doing the "wiring" up. I want to save myself some money by carrying out the "labour" work.

Then ask him all these questions.

He is the one who has to put his name to it, so he has to be the one to make all these design decisions.

You cannot go off and ask random questions on a forum like this, install various MCBs and cables, and expect him to certify it. In fact, I'm amazed that he is even letting you do anything like that. Fair enough if he's happy for you to labour for him, to save a few quid, but he is in charge, and you should do exactly what he tells you, and only what he tells you.

Okay. Thanks. I will get him in again!

 

[DESL]

Okay. Thanks. I will get him in again!

Good idea

I do a lot of such jobs but I have to be satisfied that the customer who offers to do heavy labour work is capable as BAS said the installer is responsible for the design, construction, inspection and testing and signs an installation cert to that effect.

If you have no problem working under supervision of the electrican then get him to talk through what is required.

NB I hate digging trenches!! and also wrestling with SWA on domestic installs.