Garage CU

[skipz]

Hi,
Garage consumer units, - - most I have seen come with a 16A and 6A MCB.
Are there any available with say a 16A and a 32A or even two 32A MCB`s configuration?

Reason is, I want to run 3 double sockets in my garage and then take a feed 20metres down the garden to run 3 more double sockets for my work shop.

TIA.

 

[Steve]

Buy a cheap 2-way CU empty, and put in whatever you like!

 

[kai]

On Screwfix site, it can be cheaper to buy the garage kit, and swap out the breakers for ones of suitable rating for your needs!

 

[skipz]

Tar guys,
The thought of a 5 way CU did cross my mind. I think I will take that route, as it will give me a bit more capacity for future needs.
The 5 way CU obviously comes with a 100A DP isolator, I want two 32A MCB`s, so if I take a 2.5mm^ run of T&E from the main CU RCD side to the 5 way CU, what size MCB should I feed it from? 32A again?

 

[Sarahspark]

Are you aware that this work is notifiable to your LABC under Part P of the building regs

Sarah

 

[skipz]

Yes!!

 

[Steve]

Tar guys,
The thought of a 5 way CU did cross my mind. I think I will take that route, as it will give me a bit more capacity for future needs.

This is what I did, a 5 way CU, but only used 2 of the ways. It was much easier to wire as well, than those tiny site supplies or shed supplies. I might use the otehr 3 ways in future, if we get a sauna / hot tub / kiln / LINAC.

 

[RF Lighting]

I think a LINAC would out do JohnD's smelting furnace

Where is JohnD these days anyway?

 

[Spark123]

Tar guys,
The thought of a 5 way CU did cross my mind. I think I will take that route, as it will give me a bit more capacity for future needs.
The 5 way CU obviously comes with a 100A DP isolator, I want two 32A MCB`s, so if I take a 2.5mm^ run of T&E from the main CU RCD side to the 5 way CU, what size MCB should I feed it from? 32A again?

You don't say how far from the main CU to the garage or the type of run? A 32A MCB feeding two 32A MCBs won't discriminate. 2.5mm² twin and earth is almost certainly not heavy enough for this.

 

[skipz]

The distance betwwen main CU and garage is approx 4 metres. The cable will have a straight run of a metre and then through a hole in the wall and run vertically up the garage wall to the new CU.
I thought 2.5mm^ would have been sufficient for that??

 

[JohnD]

Where is JohnD these days anyway?

here - - - ->

 

[Spark123]

The distance betwwen main CU and garage is approx 4 metres. The cable will have a straight run of a metre and then through a hole in the wall and run vertically up the garage wall to the new CU.
I thought 2.5mm^ would have been sufficient for that??

No, 2.5mm² twin and earth at room temp is rated at a maximum of 28A. When selecting a cable you need to consider how it is to be installed, the type of protective device, wether it is grouped, any thermal insulation, the ambient temperature and volt drop. When designing a circuit you also need it to discriminate i.e. only trip the breaker closest to the fault.
As you are wanting to have another distribution circuit off the garage CU then you need to try and keep volt drop to a minimum. I don't know about trying to run the lot off the RCD in the main CU, the RCDs should really be as local as they can to the point of utilisation.

 

[skipz]

Ok,
Thankyou Spark123,
I will tell you my plan!!
In the workshop, 20 metres away from the garage, I occasionally run a 3 phase air compressor. (i have a single to three phase inverter) also normal power tools, angle grinder, drill etc. (never all together)!

In the garage, I use power tools, a jet wash and occasionally a 195 amp mig welder, (again never all at the same time)!

The garage is joined to the house, so the main CU is literally a wall thickness away.

If I run a 4mm^ length of T&E into the garage from the main CU via a 32A MCB on the RCD side into a 5 way metal clad CU in the garage, then use a 32A MCB from the 5 way to power 3 double sockets in the garage wired on a ring circuit using 2.5mm^ T&E.

From another 32A MCB in the 5 way, I will run 6mm^ SWA to the workshop. In the workshop, I will install a metalclad 2 way garage CU with RCD protection with a 32A MCB and a 6A MCB to power the ring main and lights respectively.
Does all that sound adequate?
Thanks for help and advice in advance.
Skipz

 

[Spark123]

I really think you need to have an electrician come and look at your setup and see what they say.

 

[skipz]

Dam!!

I thought you would help me out their, without the "normal" seek an electrician or "this has to be checked" scenario!

Thanks anyway.