Power to the garage

[justthebeginner]

Hello everybody,
I am new I am the beginner and I need your help.
I need to supply the power to the garage. The garage is about 37 meters from the house.It`s a new house and I wouldn`t like to cut the walls to take it from the CU. I need a confirmation and an advice am I thinking correctly. It will be checked by a qualified electrician. But I would like to know am I thinking in a right way. What I am going to do:
1. Split the tails by a connector block (using the same tails size- 25mm)
2. Install the enclosure with 100amp RCD with 40amp MCB- use the 25mm wires to connect the connector block with the enclosure
3. Run the armoured cable 16mm (because of the voltage drop)connect it to that mcb, bury it and connect to the 40 Amp CU in the garage (lights- 6amp and 32 final ring for sockets)
4. I am going to use three core armoured cable and use one core as an earth.

If I am thinking in a wrong way show me the right one please.
Thank`s

 

[EFLImpudence]

1. You could. There are other ways.
2. You do not need an RCD. Switch fuse. There are other ways.
3. Not really.
4. Ok. The armour must be earthed although you may need the other core for bonding.

Outside power is not a DIY job; there are too many variables.

Please find an electrician to discuss your particular situation and ask him these things.

 

[flameport]

Having is checked afterwards is not suitable - it's either notify first and you do the work, or an electrician does the work and the notification.

What is the load in the garage - 40A seems rather excessive, as does a 32A ring circuit. In any case, a 40A MCB will not discriminate with a 32A one.

How do you intend to 'split the tails'?

Where is the enclosure with the RCD and MCB going - you stated that putting cables through the wall was not appropriate?

 

[5WW]

Are you able to isolate the tails to enable you to split them?

• 
  You'll be hard pushed to get an electrician to cert & sign off your work.
  This job isnt something a diyer should do.
  

Get a qualified electrician in, who knows what they are doing.

 

[justthebeginner]

Thank you guys,
there are too many factors just to do it in that way. I think I am going to take the power from the CU. Just connect it to the 40amp MCB. Run 16mm wires and connect this with the 16mm armoured in the enclosure (armoured will be earthed of course-using gland) on the wall outside the house.

"What is the load in the garage - 40A seems rather excessive, as does a 32A ring circuit."

The installation in the garage is already done- 40amp main switch- RCD as a switch, 32amp socket mcb and 6amp light mcb.

How do you feel this?

 

[ban-all-sheds]

The installation in the garage is already done

But not tested.

 

[flameport]

The installation in the garage is already done- 40amp main switch- RCD as a switch, 32amp socket mcb and 6amp light mcb.

That is not what the load in the garage is - shoving a 32A MCB in does not mean it is required or necessary.

What will actually be used in this garage - tools, fridge, lawnmower, nothing at all?
Is this actually a garage, or a workshop / office / other?

 

[justthebeginner]

That installation is just to have the power in a case. Any havy duty devices. InIn that case there is no point to have such big MCB in CU. I was thinking to take the power from the CU but there isn't no Rcd way in it- the garage there is already Rcd CU installed. In that way the best way would be to split the talis from themeter in service connector block and run it to the house and to the switchfuse- Wylex 63amp. The wire size is always determined by a load taken and I was thinking the garage way from the connector could be only 16mil even if the house size is 25mil- or should I use the same size? From that switchfuse run the SWA (earthed) to that CU in the garage.One of the Swa cores will be used as earth.
The other way could be to install the main switch straight after the meter and service connector after it.I wouldn't have to use the switchfuse.
Which way is better?
Many thank's!

 

[JohnW2]

... the best way would be to split the talis from themeter in service connector block and run it to the house and to the switchfuse- Wylex 63amp. The wire size is always determined by a load taken and I was thinking the garage way from the connector could be only 16mil even if the house size is 25mil- or should I use the same size? From that switchfuse run the SWA (earthed) to that CU in the garage.One of the Swa cores will be used as earth.
The other way could be to install the main switch straight after the meter and service connector after it.I wouldn't have to use the switchfuse.

You would not need a 63A fuse and very probably not even 16mm² SWA, let alone larger. I don't really understand your second option - it sounds as if it is crazy and/or dangerous.

You really need to get someone who understands what they are doing to design and sort this out for you.

Kind Regards, John

 

[justthebeginner]

John,
The reason I was thinking about a main switch is to have the possibility to switch off the power on SWA. The switchfuse is to terminate the SWA and do the safe connection.
Thank you

 

[JohnW2]

John, The reason I was thinking about a main switch is to have the possibility to switch off the power on SWA. The switchfuse is to terminate the SWA and do the safe connection.

The fuse in the switchfuse is to protect the SWA. Even if you have long tails (usually >3m) between meter and CU, it is necessary to have a fuse (in a switchfuse) protecting them.

It's the fact that you don't understand this which makes me think that, with the best will in the world, you need professional advice/assistance.

Kind Regards, John

 

[justthebeginner]

John,
I will try to test your patience.
The swa is connected to the garage CU with mcb installed and they are protecting against overload. So if the socket mcb will trip there is no chance to overload swa?
Kind regards

 

[JohnW2]

John, I will try to test your patience. The swa is connected to the garage CU with mcb installed and they are protecting against overload. So if the socket mcb will trip there is no chance to overload swa?

... and if someone puts a spade through the SWA?

If your approach were acceptable, there certainly would not be a need to have a fuse protecting long meter tails - but there is such a requirement.

Kind Regards, John

 

[justthebeginner]

Yes, you are right.
Thank's John