garage supply

[young sparky]

Hi guys, new on here so hope this is the correct place for this question, new to the game so dont be to harsh lol, plenty experience in wiring and installing containment of all types but dont no enough about cable protection and what to use.

was wiring a garage today, piped and wired and fitted out and ready to go, only thing im concerned about is the supply to it....

its only a ring main and lighting circuit in garage.
cu in garage is supplied from outside meter box. in the meter box at the house there is 80amp switch supplying house, i have a 2.5 cable in the meter box supplying driveway lights and 6mm out to the garage, wolud i be best to put a rcd 2way board in the meter box and supply it from the 80a switch???

 

[SparkyLee2008]

yeah the cables shoud be protected by an rcd and mcb so 2 2way board would be ideal. i wouldnt put it in the meter box outside tho perhaps find where the meter tails enter the house and install a henley block to split them between the exsisting board and your new rcd board. the garage board should just be main switch unit so you havent got two rcds on the circuit. or something along thoses lines sum1 may correct me

or if you have spare ways in a more modern consumer units you could use two rcbo's and take the new cables strait into the existing consumer unit

 

[telectrix]

1. how is the 6mm run, and is the garage attached to the house or remote? the 6mm needs to be supplied via a 40A ( max,) MCB .
2. does the 6mm need RCD protection,? if not, fit your RCD in the garage CU.

 

[young sparky]

cant mate, that the problem, cant get the 6mm and 2.5 mm supplys near the cu in the house as it is nowher near the outside meter box and thats were the supplys were left for me...
yes just have main switch in garage cu and 2way rcd board in outside meter box, but can i supply this 2way rcd board straight from the 80a switch

 

[young sparky]

garage not connected to house, run through duct to garage 5 meters away. would need to protect the 6mm at meter box because that were the 2.5 is nfor the drive way lights

 

[telectrix]

best way you can do it then is to henley block the house tails then fit 25mm tails to your RCD+2 MCB board.

 

[SparkyLee2008]

My reply was asuming the garage was detached from the house, maybe you should listen to more experinced members as im new and my idea was just a breif descriiption of one wiring system!

 

[young sparky]

thanks guys, very useful forum....many thanks again

 

[telectrix]

My reply was asuming the garage was detached from the house, maybe you should listen to more experinced members as im new and my idea was just a breif descriiption of one wiring system!

can't see anything wrong with your post, mate.

 

[wade88]

Hi guys,

Thought i would jump on the back of this thread as i too am brand new to the game and am looking to complete my elecsa assessment with a garage CU update and the installation of some new circuits including an SWA or SY run up the garden for some weatherproof sockets.

I believe the garage CU is fed from a 6mm also coming from the main CU under the stairs in the house. The garage is detached by quite a distance and the main CU is protected with a 60ma RCD, non spilt board with 10 ways on it.

I was looking to update the garage CU (which is a total shambles at the moment) with a 4 or 6 way RCD protected board. and run the new lighting, ring and SWA circuits from it.

I havnt got my regs book at the moment as i have left it at my mates 60 miles away... :/ what a tool...so im hoping any of you guys might be able to fill me in on any regs i need to be aware of and what essential protection i need to supply to this new set up?

Thanks lads

 

[malcolmsanford]

Hi guys,

Thought i would jump on the back of this thread as i too am brand new to the game and am looking to complete my elecsa assessment with a garage CU update and the installation of some new circuits including an SWA or SY run up the garden for some weatherproof sockets.

I believe the garage CU is fed from a 6mm also coming from the main CU under the stairs in the house. The garage is detached by quite a distance and the main CU is protected with a 60ma RCD, non spilt board with 10 ways on it. I,m assuming you mean a 63amp 30mA RCD ?

I was looking to update the garage CU (which is a total shambles at the moment) with a 4 or 6 way RCD protected board. and run the new lighting, ring and SWA circuits from it. If your garage is seperate from the house then I would suggest you fitting the RCD in the garage itself and the sub main to the Garage on a non RCD protected way. If it's an attached then you can fit it to an RCD side of the CU

I havnt got my regs book at the moment as i have left it at my mates 60 miles away... :/ what a tool...so im hoping any of you guys might be able to fill me in on any regs i need to be aware of and what essential protection i need to supply to this new set up?

Thanks lads

To be honest this is just a small fraction of information you have given us and to answer you better more information is really required

 

[wade88]

No the RCD is not a 30ma, i apologise actually for stating a figure as i cannot rightly remember but it most certainly isnt a 30ma RCD. It may infact be 100amp 100ma RCD when i think about it. Yes i appreciate the information is vague im just at work on my tea break and figured i would just throw something out there whilst i drink my coffee! and give myself something to think about for the day.

 

[malcolmsanford]

No the RCD is not a 30ma, i apologise actually for stating a figure as i cannot rightly remember but it most certainly isnt a 30ma RCD. It may infact be 100amp 100ma RCD when i think about it.So I take it that the earthing system is TT with the use of an upfront 100mA RCD. That is good becasue if the garage is detached then you can use that to protect your cable and fit the a 30mA in the garage. Yes i appreciate the information is vague im just at work on my tea break and figured i would just throw something out there whilst i drink my coffee! and give myself something to think about for the day.

So now you will need to look into perhaps adding another rod for the garage.if it's detached. you could tie it in with the house rod to bring down your Ra. Perhaps the one house rod will be good enough, you'll only find out with testing it.

 

[wade88]

The house isnt TT! Im a little concerned now. The wiring was re-done years ago by a couple of "traders" but im positive the house is TNC-S.

 

[malcolmsanford]

Well I know that some old TN-S also had ELCB or even RCD up front for additional protection but to be honest until the advent of the 16th and then more so the 17th, never seen a TNC-S with a 100mA RCD, but that is not to say that someone never fitted it.

You may also find that it could have been a TT conversion into a PME and they couldn't be bothered to remove the RCD/ELCB and use it just as a double pole isolator. Just give it a Ze that will confirm what it is.